Retinoscopy

RETINOSCOPY
By Dr. Mohamed A.A Etarshawi
M.D Ophthalmology

HISTORY OF THE RETINOSCOPE
•The observations that led to clinical <
retinoscopy> were made in 1859 with a plane
mirror ophthalmoscope lighted by a candle,
when Sir William Bowman noted a linear
shadow seen when examining an astigmatic
eye.
• By 1875, the optics were explained and the
procedure was described as a “shadow test,”
an allusion ةراشإ . عاملإ to neutralization. H.
Parent coined the term <retinoscopy> in 1881

HISTORY OF THE RETINOSCOPE
•The earliest retinoscopes used a mirror to
reflect a candle, which produced a “spot” of
light. It was soon discovered that a linear
streak of light could be produced with slit-
shaped mirrors.
• Early electric retinoscopes used spiral
filament bulbs and a rotating slit. Jacob
Copeland introduced a linear filament bulb
that produced a sharp, bright line of light.
The Copeland streak retinoscope set the
standard for future retinoscopic
developments.

OPTICS OF THE RETINOSCOPE
•The streak retinoscope has supplanted لّ محِلّيَحِلّ
ه لّ محَحِلّمَحِلّ the spot retinoscope in the modern eye
clinic, and only the streak retinoscope is
discussed in this chapter.
• Although the various brands ةكرام of streak
retinoscopes differ in design, they all work
similarly. Light is produced by a luminous
filament within the base of the handle and
emanates from a mirror in the head as a
linear streak, with both orientationه جُّهوَحِلّتَحِلّ ; and
vergence رادحنإ ، ليم controlled by the
retinoscopist.

HISTORY OF THE RETINOSCOPE
•The streak of light passes through the
patient's tear film, cornea, anterior chamber,
lens, vitreous chamber, and retina. It is then
reflected from the choroid and retinal
pigment epithelium as a linear red reflex that
passes back through the sensory retina,
vitreous, lens, aqueous, cornea, and tear
film, through the air between the patient and
the examiner, and into the head of the
retinoscope, through an aperture in the
mirror.

OPTICS OF THE RETINOSCOPE
•Finally exiting through the back of the
retinoscope into the retinoscopist's
own eye.
• By observing qualities of the reflected
light (the reflex) after it leaves the
patient's eye, the retinoscopist can
make determinations about the
patient's refractive state.

streak retinoscope
Diagrammatic cross-section of streak retinoscope

Diagrammatic cross-section of streak
retinoscope.
•Light from the filament passes through the
lens to the mirror, where it is reflected
toward the patient. The examiner views
through the aperture behind the mirror.
•The arrows represent the two controllable
functions. The curved arrow indicates that
the bulb may be rotated. The straight arrow
indicates that the vergence of the light rays
may be altered by changing the filament to
lens distance.
•The filament is shown at the focal length of
the lens so that parallel light rays emerge.

OPTICS OF THE RETINOSCOPE
•Explaining the optics and proper usage
of the retinoscope can be a confusing
business. To help simplify the text, we
have chosen to use the feminine. ث نّ مؤم
ريمض pronouns (e.g., “she” and “her”)
when referring to the retinoscopist, and
the masculine ones (e.g., “he,” “him,”
and “his”) when referring to the patient.

OPTICS OF THE RETINOSCOPE
•All streak retinoscopes are made of the same
fundamental components: light source,
condensing lens, mirror, and sleeve .
•The light source is a light bulb with a fine,
linear filament, which projects a fine, linear
streak of light with the passage of an electric
current.
•The filament (therefore the streak), can be
rotated 360 degrees by rotating the sleeve of
the retinoscope. Currently, most retinoscopes
use a halogen bulb, which projects a very
bright streak.

OPTICS OF THE RETINOSCOPE
•The condensing lens is a plus lens, which
exerts positive vergence on the streak, which
is emitted from the point-source filament in a
highly diverging manner.
• The position of the lens in relation to the
light filament can be altered by raising or
lowering the sleeve.
•In this way, the vergence of the streak that is
emitted from the retinoscope can be
controlled by the retinoscopist, as described
subsequently.

OPTICS OF THE RETINOSCOPE
•The mirror bends light that originates in the
handle and is initially projected upward
toward the ceiling, to instead exit the
retinoscope along an axis parallel to the floor
so that it can be projected into the patient's
eye. The mirror should not reflect 100% of
visible light; rather, it must allow some light
to pass through it.
•Only in this way can the retinoscopist have a
view into the patient's pupil that is coaxial
روحملا دحتم to the path of the streak.

CONTROLLING THE PROPERTIES OF THE
RETINOSCOPE
•The basic idea behind the retinoscope is that
the retinoscopist creates a streak of light,
projects it into a patient's eye, bounces it دّ تري
off his retina, and makes deductions جاتنتسا
concerning the patient's refractive status
based on what the image of that streak looks
like when it reaches the retinoscopist's eye.
To aid her in this task, the retinoscopist has
control over, and can easily vary, certain
aspects of the system.

CONTROLLING THE PROPERTIES OF THE
RETINOSCOPE
Two things she can control have nothing to
do with the intrinsic properties of the
retinoscope she is holding :
•The distance between the retinoscopist's
eye and the patient's (W.D).
•Which lenses she may be holding between
the patient's eye and her own.

CONTROLLING THE PROPERTIES OF
THE RETINOSCOPE
•Optical effects of moving the retinoscope
bulb to change the filament to lens distance;
this type of retinoscope emits convergent
light when the sleeve is moved up. Note the
vergences of the emerging rays:
• (left) concave mirror effect is produced
when bulb is moved down;
• (right) plane mirror effect is produced when
bulb is moved up.

CONTROLLING THE PROPERTIES OF
THE RETINOSCOPE
Plane mirror
Concave mirror
Movement of the light source

CONTROLLING THE PROPERTIES OF THE
RETINOSCOPE
However, two properties over which the
retinoscopist has total control are completely
intrinsic to the retinoscope she is holding.
•1-The first is the orientation of the streak as
it leaves the retinoscope. Because the light
source for the retinoscope is a fine filament,
the light emanates from the retinoscope as a
fine streak.

CONTROLLING THE PROPERTIES OF THE
RETINOSCOPE
•By rotating the light source, the
retinoscopist can easily alter the
orientation of the streak by more than
360 degrees. Merely by rotating the
sleeve on the handle of the retinoscope,
she can project a streak whose
orientation is parallel to the floor, or
perpendicular to it, or any meridian in
between.

CONTROLLING THE PROPERTIES OF THE
RETINOSCOPE
•2-The second property that can be controlled
easily by the retinoscopist is the vergence of
the incident streak. With the touch of a finger
(or thumb), the retinoscopist can alter the
streak so that it leaves the retinoscope as
converging, diverging, or even parallel light.
This feature gives the retinoscopist an
incredible قدصي ل amount of power in evaluating
a patient's refractive state. Unfortunately, it is
probably the most underused feature of the
retinoscope.

CONTROLLING THE PROPERTIES OF THE
RETINOSCOPE
•Changing the distance between the light
filament and the condensing lens alters the
vergence of the emitted streak. This can be
accomplished by raising or lowering the
sleeve in the handle of the retinoscope.
•This is the most fundamental way in which
different models of retinoscope will contrast,
رياغتي ف لتختلا and it is obviously important for
the retinoscopist to be familiar with the type
of retinoscope with which she is working.

CONTROLLING THE PROPERTIES OF THE
RETINOSCOPE
•The condensing lens is fixed, and the light
source can be raised or lowered by moving
the sleeve up or down (Fig. 2).
•When the sleeve is raised in these
retinoscopes, the streak emanates as a
diverging beam; when the sleeve is lowered,
the streak emanates in a converging nature ,
and therefore we use the term “sleeve up”
when the retinoscope emits diverging light
and “sleeve down” when it emits converging
light.

CONTROLLING THE PROPERTIES OF THE
RETINOSCOPE
By altering the vergence of the emitted streak, the
retinoscopist is actually manipulating its focal
point, the point where the emitted light comes
to focus in a point in real or virtual space.
When in maximum convergence (sleeve up), that
focal point is a real image located 33 cm in front
of the retinoscope. (You can test this by moving
the palm of your hand in front of the
retinoscope at a distance of 33 cm, then turning
it on with the sleeve raised all the way up.

Figure 2
concave mirrorplane mirror
Movement of the lens

CONTROLLING THE PROPERTIES OF
THE RETINOSCOPE
•Optical effects of moving the lens to
change the filament to lens distance;
this type of retinoscope emits
convergent light when the sleeve is
moved up. Note the vergences of the
emerging rays: (left) plane mirror effect
when lens is moved down; (right)
concave mirror effect when lens is
moved up. 2

DETERMINING THE VERGENCE OF THE
RETINOSCOPE BEAM Lecture 1
To determine the vergence of a retinoscope
at any sleeve adjustment, a simple trick
called Foucault's Method (Fig. 4) can be
used. The most instructiveيّ فِييقِيثْقِتَ part of
this exercise is shown in Figure 4A.
Note that when a card is introduced at the
edge of a converging beam, an opposite
movement is produced on a screen
located beyond the focal point.

Figure 4
against” motion
with” motion
with” motion
Screen
Rays converging beyond screen
Diverging rays
Rays converging at a focal point before screen

Foucault's method for determining vergence of
rays emerging from a retinoscope
• A card or your hand is introduced close to
the retinoscope and moved at right angles to
the emerging rays. Observe the shadow
produced in the unfocused image on a
screen or wall in a darkened room.
• (A) Rays converging at a focal point before
screen cause an “against” motion.
• (B) Rays converging beyond screen cause a
“with” motion.
•(C) Diverging rays cause a “with” motion.

•Foucault's method for determining vergence
of rays emerging from a retinoscope. A card
or your hand is introduced close to the
retinoscope and moved at right angles to the
emerging rays.
•Observe the shadow produced in the
unfocused image on a screen or wall in a
darkened room.
• A. Rays converging at a focal point before
screen cause an “against” motion.
•B. Rays converging beyond screen cause a
“with” motion.
• C. Diverging rays cause a “with” motion.

Calibration of the Converging
Beam
Bring the sleeve all the way up and place it
against a reflecting surface such as the wall.
Move away from the wall and observe from
the side (not through the peephole) until the
streak is in sharp focus on the wall. You
should note that when the retinoscope is
moved beyond that distance, the streak will
go out of focus because the filament light
has converged and then diverged (see Fig. 4
A).

•Return to the point of sharp focus and
measure to determine the focal point of
the retinoscope: it should be about 33
cm, which corresponds to + 3.00 D.
•Sit in the patient's examination chair
and aim the retinoscope toward the
distant wall while moving the sleeve up
and down.

Calibration of the Parallel Beam
•Watch where the finest focused image of
the filament is observed. Note the
relative position of the bottom of the
sleeve with regard to the range of sleeve
movement.
•In that position, the retinoscope beam is
as parallel as possible and it has no
vergence and thus is focused at infinity.

NEUTRALIZATION
RETINOSCOPY
Neutralization is performed with the retinoscope
held at a constant predetermined distance
from the patient with the sleeve all the way
down (light emitted in a diverging manner).
The retinoscopist makes decisions about the
patient's refractive error based on the
appearance of the retinoscope reflex after it is
reflected off the patient's fundus and back
through the pupil (Fig. 16).

NEUTRALIZATION
RETINOSCOPY
•What the retinoscopist sees is not the
image “on the retina” ,but rather the
magnified image “of the retina.”
• Therefore, discussion about
neutralization must begin with
discussion about the retinoscopic
reflex at neutralization.

THE NEUTRALIZATION REFLEX
•When performing neutralization the
retinoscopist shines diverging light
through the patient's pupil from a
standard working distance (usually 66
cm).
•This light is reflected off the patient's
fundus, and in this way, the fundus
acts as a new point source of light.
This is called the illuminating system.

THE NEUTRALIZATION REFLEX
•The light that originates from the luminous
retina then passes through the patient's
vitreous, lens, pupil, aqueous, and cornea,
until it finally exits the patient's eye on its
way back to the retinoscope. This is called
the viewing system.
•The retinoscopist must be able to
differentiate between the illuminating and
viewing systems because different
techniques of retinoscopy can depend on
varying the components of one but not the
other.

THE NEUTRALIZATION REFLEX
•1-When diverging light is shone onto an
emmetrope's retina, the retina becomes
luminous and acts as a point source of light.
The rays of light then escape his eye in a
parallel fashion. If this concept is not
intuitive, يّ هيدَبَ merely follow the standard
light ray diagram backward.
•2-In similar fashion, light starting as a point
on a myope's luminous retina is emitted as
converging light, where more myopic
individuals emit more highly converging light
than less myopic ones.

THE NEUTRALIZATION REFLEX
•3-Similarly, light starting as a point on a
hyperope's luminous retina is emitted as
diverging light, and hyperopic patients emit
more diverging light than less hyperopic
ones.
• The vergence of the rays emitted from the
eye determines the qualities of the reflex
seen by the retinoscopist.
•A neutralization reflex occurs under the
circumstance when the far point of the eye
correlates ةيماظن ةروصب طبري with the location
of the peephole of the retinoscope

•If a retinoscopist were to examine an
emmetropic eye at infinity, she could make
assumptions ضارتفا on the diverging,
converging, or parallel nature of the reflected
light by sweeping the retinoscope streak
back and forth across the patient's pupil.
•However, it is not possible to perform
retinoscopy from an infinite distance; it is
customary to adapt a working distance of 66
cm, corresponding to + 1.50 D.
•By introducing + 1.5 lens in front of the
subject's eye, the far point of a plano
prescription is relocated to 66 cm.

•In this circumstance, what the retinoscopist
is truly evaluating is whether the
:-retinoscope lies between the patient's eye
and far point, lies at the far point, or lies
beyond it.
1. If the patient is an emmetrope, the far point
lies on the horizon, and therefore the
retinoscope always must lie between the
patient's eye and far point.
2.If the patient is a hyperope, the far point
actually lies beyond the horizon, and the
retinoscope also lies between the patient's
eye and far point.
FP
FP

3-Things are more interesting, however, when
evaluating myopes in this way.
Light is emitted from a myope in a converging
manner so that the far point is somewhere in
real space (finite) in front of the myope's eye.
It is possible for the retinoscope to be placed
A- between the patient and far point,
B-exactly on the far point, or
C-out beyond the far point.

THE NEUTRALIZATION REFLEX
This relationship depends, of course, on
both the location of the retinoscope
(W.D), and the level of myopia (which
determines the location of the far
point).
AB
C

•If the retinoscope is placed between the eye
and far point (as it is for all emmetropes and
hyperopes, and some myopes) and turned so
that the emitted streak is swept from side to
side across the patient's pupil, the light
reflex seen inside the pupil appears to sweep
in the same direction as the light emitted
from the retinoscope (seen on the patient's
iris, lids, brow, and cheek).
•This motion is called “with” motion because
the light that is afferent to the retinoscope
seems to move “with” the light that is
efferent from the retinoscope

THE NEUTRALIZATION REFLEX
•Fig. 17. The optical basis for neutralization <
retinoscopy>. The location of far points
produces the “with” and “against” motions
for a retinoscope with a divergent beam
when performing neutralization retinoscopy.
“With” motion is seen under all
circumstances except when the far point of
the eye-corrective lens system is situated
between the cornea and the peephole بقث of
the retinoscope. The far point of the
illustrated eye is at the peephole and is thus
neutralized.

Figure 17

Lecture 2
With” motion reflex in
hyperopia

Fig. 18. “With” motion reflex in
hyperopia
A “with motion” reflex of light comes into the
shadow projected in the optical system from
the aperture of the retinoscope or the
examiner's pupil.
The rays from the filament to the retina are not
shown. They form an unfocused horizontal
filament image on the retina of the patient
that acts as a new object with its image
behind the retina.
When the retinoscope is tilted slightly, the
object (RETINA) moves down and the image
(REFLEX) moves down and vise versa. This
is seen as a “with motion” reflex.

Figure 19 against motion reflex of
myopia
•If the retinoscope is placed beyond the patient's far
point and swept from side to side across the pupil,
the light reflex (efferent) seen inside the pupil
appears to sweep in the opposite direction as the
streak emitted from the retinoscope (afferent )
Fig. 19
•This motion is called “against” motion because
the light emitted from the eye (efferent) appears to
move “against” the light that is emitted directly
from the retinoscope (afferent (.

Fig. 19. Origin of the “against”
movement in myopia

“On-off” phenomenon
•When the retinoscope is placed exactly on the
patient's far point, neither “with” nor “against”
motion is seen. At this point, all the light emitted
from the patient's eye enters the retinoscopist's
eye simultaneously.
• At exact neutrality, in a spherical eye with a small
pupil, the retinoscopist may see no motion at all;
rather, the patient's pupil seems to suddenly fill
with light as the streak moves across it.
•This is obtained in myopic eye exactly reciprocal
to W.D in diopters.
•This “on-off” phenomenon is important to
recognize because it serves as the end point
when performing the technique of neutralization.

Other qualities of the reflex
•In addition to its direction of movement, other
qualities of the reflected retinoscope streak
can be evaluated. These qualities all give the
retinoscopist clues as to how close to the far
point the retinoscope is being held.
The three most important qualities of the reflex
are:
1. the speed at which it moves,
2. its brightness,
3.its width.

Other qualities of the reflex
If one thinks of the reflex at the
neutralization point as :
•infinitely fast (so fast that it immediately
fills the pupil without apparent motion),
• infinitely ه ُ bلَحِلّ دَّ حَحِلّ ل ; دوددُ bحْدُمَحِلّ رُ bيْدُغَحِلّ bright, and
•infinitely wide, it is easy to understand
what the reflex should look like when the
retinoscope is either near to, or far from,
the neutralization point Fig. 20

qualities of the reflex
•When the retinoscope is held near the patient's
far point, the reflex should appear fairly fast,
bright, and wide.
•As the retinoscope is moved farther from the far
point, the reflex appears to move slower and is
dimmer and thinner.
•The retinoscope can eventually be moved so far
from the patient's far point that the reflex is slow,
wide, and dim enough that it is quite difficult to
recognize as a reflex at all.

Other qualities of the reflex
•Fig. 20 .Neutralization retinoscopy diagram of
changes in characteristics of reflex as in the
zone surrounding the point of neutrality.
•At neutrality, the reflex motion may be so fast
that it cannot be detected. The end point or
end zone should be approached from the
“with” reflex side and the judgment of
neutrality made erring لزِييَ . ئطخي
toward the “with” reflex rather than the
“against” reflex.
•The neutral point lies within the
neutralization zone where neutralization is
best observed. (

Figure 20
Fig_ 20.htm

Optics of the Neutralization
Reflex
•Five features characterize the neutralization end
point, the point at which neither a “with” nor
“against” reflex can be identified. Three of these
are considered to define the end point, but two
others can also be observed. The three standard
characteristics are :
•Increases in speed, brightness, and width of
the moving image. )1,2 &3 )
•To these can be added : the “on-off phenomenon”
(the intermittent disappearance of the observed
reflex) and the scissors reflex) .4 &5 (

Optics of the Neutralization
Reflex
1-Speed of the “with” or “against” motion:
• If the retinoscope mirror is tilted in a highly
ametropic eye, the resultant reflex is (more rapid )
imaged at a far point that is much closer to the
eye than the reflex of an almost emmetropic eye,
the far point of which is located at a much greater
distance.
• With regard to the subject's pupil, movement of
the image at the far point of the almost
emmetropic eye will seem to have a greater
angular velocity or speed.

Optics of the Neutralization
Reflex
•It should be stressed that the direction of
movement of the fundus image is not influenced
by the patient's ametropia ( illuminating system).
•The “with” or “against” movement is a function of
the observation (VIEWING) system, thus an
“against” movement occurs only when the eye
and external lens system have a far point lying
between the patient's eye and the retinoscope
peephole )High myopia)

Optics of the Neutralization
Reflex
2-Brightness of the image:
•As neutrality is approached, all of the rays
emerging from the patient’s eye are focused at
the peephole, where they provide the brightest
image that the examiner observes. Illumination
increases inversely to the square of image size.
•At any other focal distance, some or all of the
rays of light will not reach the peephole and the
image becomes duller Fig. 21

3-Width of reflex
•In general, the width of the streak reflex and the
apparent speed of the streak reflex as it moves
across the pupil give an indication of how far you
are from neutrality.
•Young eyes that are not diseased and have not had
surgery give the most defined reflexes. Corneal
diseases, cataracts, IOLs, hazy posterior capsules,
and cloudiness in the vitreous distort the reflexes
and change the "rules" of appearance.
•Sometimes width and speed do not give reliable
clues and you must just rely on apparent with-
motion to arrive at the best retinoscopic estimate.

A very wide (almost filling the pupil), slow
moving streak reflex indicates that you are a long
way from neutrality. For instance, the with or
against reflex you would see at plano when
streaking a (– or +5.00 hyperope.(

As we add plus sphere power the
streak tends to narrow and speed up
in its apparent motion.
3-Width of reflex

As we continue adding plus sphere
power and approachابيرقت neutrality, the
streak widens again and speeds up even
more.
3-Width of reflex

At neutrality the streak reflex
widens more to completely fill the
pupil.
3-Width of reflex

3-Width of reflex
In astigmatism :Streaking one meridian gives
you against- motion, and streaking the
meridian 90 degrees away gives you with-
motion.
• Streaking one meridian gives you with-
motion (or against- motion) with a wide
streak reflex, and streaking the meridian 90
degrees away gives you the same motion
but with a narrower streak reflex.

3-Width of reflex
a wide streak reflex,
narrower streak reflex

3-Width of reflex
•As we add plus sphere power, the
reflex at 90 narrows and the reflex at
180 quickly widens and reaches
neutrality.

Optics of the Neutralization
Reflex
4-The on-off phenomenon: Although the
retinoscopic reflex is bright and wide on
either side of neutrality, the reflex may
disappear completely when the retinoscope
peephole is exactly conjugate to the eye-
corrective lens system i.e far point of the
examined eye. (see Fig. 21 (.
•Fortunately, neither the patient's eye nor the
examiner's eye and hand can maintain this
exact position for long, but astute يكذ
retinoscopist may notice the on-off
phenomenon at neutrality.

Optics of the Neutralization
Reflex
• Fig. 21. The origin of the on-off
phenomenon at neutrality. The far point of
the eye is situated at the peephole of the
retinoscope. Either all or none of the rays
will pass through the peephole with the
slightest shift in the subject's eye or the
retinoscope or the retinoscopist's eye,
causing the retinoscopist to see the
contents of the pupil as either filled with
light or black.

Fig. 21 the on-off phenomenon at
neutrality
Patient’s eye

Optics of the Neutralization
Reflex Lecture 3
5-The scissors reflex: The refractive elements of
the eye are not perfectly spherical. Thus, the
center of the optical path may be slightly myopic
when compared with that of the periphery.
The amount of aberration may be small, but under
circumstances of perfect neutralization and a
widely dilated pupil, the center of the optical path
may return a “with” motion while the periphery
returns an “against” motion.

Optics of the Neutralization
Reflex
•This pattern of opposing central and
peripheral retinoscopic movements is
known as a scissors reflex. There is only a
small dioptric distance over which the
scissors reflex can be detected. The entire
reflex returns to all “with” or all “against”
motion within about 0.50 D on either side
of neutralization). narrow zone)

Estimating Low Myopes via
Neutralization Without Lenses
•By now the reader should have determined that
it is in fact quite possible to neutralize low
myopes without the use of lenses.
•The trick is to place the retinoscope directly on
the patient's far point, sweep the retinoscope
streak across the patient's pupil with the sleeve
down, recognize the “on-off” phenomenon of the
neutralization reflex, measure the distance from
the patient's eye to the retinoscope in meters,
take the reciprocal—thus converting from meters
(distance) to diopters (vergence)—and the
patient's refractive error has been determined.

Neutralization Without Lenses
•For example, neutralization for a -2.00-D myope
can be seen by placing the retinoscope 50 cm
from the patient's eye, and for a -4.00-D myope
by placing the retinoscope 25 cm from this
patient's eye (without considering a certain W.D(
• Neutralization for an emmetrope can only be
done in this fashion by placing the retinoscope
infinitely far from the patient's eye—theoretically
possible, but not practically feasible. مئملم . يّ م لمع

NEUTRALIZATION Without Lenses
•Because the far points of hyperopes do not lie in
real space (they lie beyond infinity), hyperopes
cannot be neutralized in this way.
•The aforementioned technique describes a way
to estimate a low myope's refractive error
without the use of lenses.
•The key to this method is that the retinoscopist
must change the distance that the retinoscope is
held from the patient's eye when trying to find
the far point.

Performing neutralization
•When performing neutralization she does exactly
the opposite—she holds the retinoscope at a
constant specific working distance and uses
lenses to bring the patient's far point to the
retinoscope.
•The first thing that a retinoscopist must do is
choose a comfortable working distance. She
wants to be as far from her patient as possible
while still being close enough to comfortably
manipulate lenses in front of his eye. Thus, the
working distance usually is described as “arms
length” away from the patient.

Performing neutralization
•For the average retinoscopist, this distance
works out to about 66 cm. Taller retinoscopists
may prefer 75 cm, whereas shorter ones may
use 50 cm.
• It is not uncommon for retinoscopists to work
closer than their usual working distance in
difficult cases, such as small children, or adults
with cataracts or small pupils.
• The actual working distance does not matter as
long the retinoscopist is aware of the distance
and adjusts her calculations accordingly.

Performing neutralization of
against” motion
•The retinoscopist should be able to sit at her
comfortable working distance while using lenses
to bring the patient's far point to her.
•The retinoscopist accomplishes this featلٌ مع . لٌ مع
ذّ مفَحِلّ by sweeping the retinoscope streak across the
patient's pupil and evaluating the direction,
speed, brightness, and width of the reflex.
•If she observes “against” motion, the
retinoscope must lie beyond the patient's far
point, and the retinoscopist can move the far
point toward the retinoscope by placing a minus
lens in front of her patient's eye.

Performing neutralization of
against” motion

Performing neutralization of
against” motion
•If the reflex is fast, bright, and wide, the
retinoscope must have been near to the patient's
far point, and a weak minus lens should be
chosen.
•However, if the reflex is slow, dim, and narrow, the
retinoscope probably lies a greater distance from
the far point, and a stronger minus lens should be
chosen.
• If “with” motion is observed after a minus lens is
placed before the patient's eye, the patient's far
point has been moved beyond the retinoscope
because too strong of a minus lens was chosen.
This lens should be removed and replaced with a
weaker minus one.

Performing neutralization of “with”
motion
•Similar manipulations are performed if “with”
motion is initially seen when neutralization is
begun. In such cases, the far point must lie
beyond the retinoscopist's comfortable
working distance.
•Again, how far away the far point lies can be
estimated by judging the quality of the reflex.
• A plus lens then is chosen to bring the far
point forward toward the retinoscope.

Performing neutralization of “with”
motion
•Whenever possible, the retinoscopist should try
to manipulate the far point in such a way that
“with” motion is being observed.
•A “with” reflex typically is sharper and easier to
judge than an “against” reflex. Thus, if
“against” motion is seen, neutralization will be
easier to perform if a strong enough minus lens
is placed to push the far point beyond the
retinoscope, so that the retinoscopist can
observe “with” motion.

minus lenses in front of younger
patients can excite accommodation
•Care must always be taken, however, when
putting minus lenses in front of younger
patients because they can easily “eat up”
this minus by accommodating, thus leading
the less careful retinoscopist down the
wrong path.
•It should also be noted that the
neutralization end point is not exactly an
end point—rather it is an end zone that
measures about half a diopter in depth (see
Fig. 20(

“zone of doubt” varies with pupil
size and working distance
•The true size of this “zone of doubt” varies with
pupil size and working distance —it is narrowest
with a small pupil and close working distance.
•Best results are achieved when entering the
zone of doubt from the plus side, by watching
the “with” motion reflex get faster, brighter, and
wider until the retinoscopist is convinced the
neutralization reflex has been achieved.
• If the zone of doubt is entered from the minus
side (through “against” motion), there is a
greater chance for error.

The neutralization reflex
•Eventually, after just a few different lenses
are placed before the patient's eye, the
retinoscopist can observe the neutralization
reflex.
•At this point the goal is achieved, and the
retinoscopist has managed to bring the
patient's far point to the retinoscope (which
is being held at the working distance).
•The retinoscopist is now ready to write a
spectacle correction )؛ prescription(.

CORRECTING THE PRESCRIPTION FOR THE
WORKING DISTANCE LENS
•However, the lenses currently in front of
the patient's eye do not represent the
correction needed to see clearly at infinite
distance; rather, the lenses represent the
correction needed to see clearly at 66 cm.
•The patient will be quite dissatisfied ريغ
ضٍ ار if given a prescription for a pair of
glasses that allows for clear vision only 66
cm away or closer.

CORRECTING THE PRESCRIPTION FOR THE
WORKING DISTANCE LENS
•The retinoscopist must always remember
to modify the prescription for distance
vision, a mathematical manipulation called
correcting for the working distance.
•The gross power is that which the
retinoscopist is holding when retinoscopy
is completed.
•This corresponds to the power that brings
light from the patient's luminous retina to
focus at the working distanceِلّ( on the
peephole of the retinoscope(.

CORRECTING THE PRESCRIPTION FOR THE
WORKING DISTANCE LENS
•The net power is that which neutralizes
the patient's refractive error for good
distance vision—the power that focuses
light from the luminous retina of the patient
to a point at the horizon. )His far point
must be at infinity after full correction).

CORRECTING THE PRESCRIPTION FOR
THE WORKING DISTANCE LENS
•The mathematical computation بابسَحِلّتِلّحْدُ اِلّ ; ءابصحْدُ إِلّ is
simple. The retinoscopist merely subtracts the
working distance (in diopters) from the gross to get
the net power.
• For example, when the working distance is 66 cm
1.50 +)= D) and the patient is neutralized with a
•-2.5 D. lens, the gross power minus the working
distance equals the net power,
or: -2.5 - (+ 1.5) = - 4D.
•The retinoscopist will give a prescription for a - 4D.
lens. The previous discussion describes
neutralization of spherical patients.

NEUTRALIZATION OF ASTIGMATIC EYES
•In patients with astigmatism, the reflex seen
in the pupil has one more quality in addition
to speed, brightness, and width. The reflex in
patients with astigmatism also appears to
“break” as the light filament is rotated Fig.
22. The retinoscope reflex seen in the
patient's pupil will not be continuous with the
streak lying on the cornea, lids, forehead,
and cheek; it will appear broken.
•There will be, however, two meridians where
the retinoscope reflex will be continuous with
the streak—where it will not appear broken.

NEUTRALIZATION OF ASTIGMATIC EYES
•These meridians correspond to the two axes of
the patient's astigmatism. The retinoscopist
merely needs to neutralize these two meridians
separately and combine them to come up with the
desired spectacle correction
• This can be done using only spherical lenses (as
is best when neutralizing children with loose
lenses), spherical and plus cylindrical lenses
(using a plus cylinder phoropter or loose lenses
and trial frames), or spherical and minus
cylindrical lenses (using a minus cylinder
phoropter or loose lenses and trial frames).

NEUTRALIZATION OF ASTIGMATIC EYES
•Let us further explore the methods of
neutralizing astigmatic individuals in whom
the less plus (or more minus) axis is
neutralized first and the more plus (or less
minus) axis is neutralized second.
• When neutralizing the axes in this order,
the retinoscopist can use either only
spherical lenses, or spherical and plus
cylindrical lenses.

Fig. 22.phenomenon Break
The line between the streak in the pupil
and outside the pupil is broken when
the streak is off the correct axis. (

BREAK PHENOMENON
•Astigmatism can also be detected by
observation of the break phenomenon.
It is useful in refining the axis of large
astigmatic cylinders because one can
observe a discontinuity, or “break,”
between the enhanced intercept axis
and that of the retinal reflex when the
retinoscope filament beam is rotated
somewhat away from the correct
cylinder axis (see Fig. 22).

•Procedure for neutralizing an astigmatic eye
•1. The first step is to neutralize one of the meridians.
You will be adding plus sphere power and streaking each
of the primary meridians after each power change.
•The meridian with the narrow, fast reflex will neutralize
first. This meridian will be 90 degrees away from the
meridian with the widest, slowest streak reflex.
• In this example, the 180 degree( right one ) meridian will
neutralize first.

As we add plus sphere power, the reflex at
90(left ) narrows and the reflex at 180 (right )
quickly widens and reaches neutral point.
Procedure for neutralizing an astigmatic eye

•2. The next step is to confirm/identify the axis of
the astigmatism. We have a good idea of what the
axis is from the neutralization process. There are
several clues that we can use:
A.The Thickness Phenomenon
B.The Intensity Phenomenon
C.The Break and Skew Phenomena
D.Straddling the Axis
Procedure for neutralizing an astigmatic eye

The Thickness Phenomenon :
The streak reflex appears to be narrowest ( left ) when
we are streaking the meridian of the correct axis.
As you move away from the correct axis, the streak
reflex becomes wider ( right ).
Procedure for neutralizing an astigmatic eye

Procedure for neutralizing of an astigmatic
eye
•The Intensity Phenomenon
The streak reflex appears brightest
when you are streaking the
meridian of the correct axis.
As you move away from the correct
axis, the streak reflex becomes
more dim (less bright ).

The skew phenomenon:
If we streak a meridian that is away from the
meridian of the correct axis, the reflex will
tend to travel along the correct meridian
rather than follow the streak. This guides us
back to the correct meridian.
The skew phenomenonThe skew phenomenon
Correct axis
Procedure for neutralizing an astigmatic
eye

•Straddling the Axis
Assuming that there is regular astigmatism present,
when one meridian has been neutralized, the meridian
exactly 90 degrees away will have the strongest, most
defined with- motion reflex.
Procedure for neutralizing an astigmatic eye

•
The axis can be confirmed by streaking
the meridians 45 degrees to each side
of what we believe to be the meridian of
the correct axis.
In this case we believe that streaking the
90 degree meridian gives the most
defined reflex.
We streak the 45 degree meridian and the
streak reflex widens and degrades in
sharpness.
The same thing happens when we streak
the 135 degree meridian. This confirms
90 degrees as the correct meridian.
45 degrees
135 degrees
Straddling the Axis
Procedure for neutralizing an astigmatic
eye

STRADDLING
When the cylinder power is weak, straddling
reveals an initial incorrect estimate of the axis
location.
The thinner image is called the “guide” because
it guides us to adjust the plus-cylinder axis
toward the thinner image.
This step provides the initial detection of
astigmatism, and the phoropter axis can be
adjusted so that plus lenses can be dialed into
place along the enhanced meridian.

Straddling
•The straddling meridians are 45 degrees off
the glass axis, at roughly 35 and 125
degrees. As you move back from the eye
while comparing meridians, the reflex at 125
degrees remains narrow (A) at the same
distance that the reflex at 35 degrees has
become wide (B). This dissimilarity indicates
axis error; the narrow reflex (A) is the guide
toward which we must turn the glass axis.

Procedure for neutralizing an astigmatic
eye
•If the reflex in one of the straddle
meridians is narrower than the reflex in
the other straddle meridian, then we
would adjust our estimated axis in the
direction of the straddle meridian with
the narrower reflex (guide).
•We would retest 45 degrees to each
side of the new axis to confirm that the
reflex in each straddle meridian is
equally wide.

26

Spherical Lens Technique
•The first step is for the retinoscopist to find
the least plus axis. The retinoscope streak is
swept back and forth across the pupil while it
is rotated 360 degrees by rotating the light
filament in the handle.
• The retinoscopist then observes at which
two meridians the retinoscope reflex does
not appear broken—in cases of regular
astigmatism, these two meridians should be
90 degrees apart.

Spherical Lens Technique
•The retinoscopist then compares the reflex in one
meridian to the reflex in the other, noting which
meridian's streak exhibits more “against” (slower,,
broader , dimmer) or less “with” (faster, thinner,
brighter) qualities than the other.
•The second meridian is neutralized first. If the
reflex in one meridian shows “with” motion and in
the other shows “against” motion, the meridian
with the reflex that shows “with” is neutralized
first

•The more minus meridian of the astigmatic person
is then merely neutralized (second ) much as the
spherical myope or hyperope described
previously.
•The axis of the streak is held along the meridian
line and swept in a direction perpendicular to it i.e
(if the 90-degree axis is being neutralized, the
streak is oriented straight up and down and swept
from side to side) perpendicular to 90 degrees.
Spherical Lens Technique

Spherical Lens Technique
•At first, it is not intuitive that the streak be held in
the same orientation as the axis meridian
because one is searching for the power of the
astigmatism, and the power lies not along the
axis, but perpendicular to it.
•Here the retinoscopist must remember that the
power is found not by holding the streak still
(fixed ) , but rather by sweeping (moving ) it
across the pupil.
•The retinoscope streak is rotated 90 degrees,
and the reflex is re-examined.

Spherical Lens Technique
• The reflex should not appear broken in the
new meridian—a broken reflex signifies that
either the retinoscope streak is not exactly
aligned along the patient's second axis or that
the patient has irregular astigmatism.
• If the reflex is not broken, it is neutralized
with spherical lenses. If spherical lenses are to
be used, the second meridian is neutralized in
exactly the same manner as the first after
removal of the lenses used before and starting
a new steps to neutralize the other meridian
also with spherical lenses .

Spherical Lens Technique
•Once the neutralization reflex has been
found in the second meridian, the
retinoscopist again subtracts the
working distance from the power in the
2 meridians and records the lens power
needed to correct the patient for each
particular axis. The difference in power
of lenses between the 2 meridians is
considered astigmatism.

Spherical Lens Technique
•A simple conversion then needs to be performed before
presenting the patient with the proper spectacle
prescription, as follows:
• Q: A patient is neutralized with the following lenses at a
working distance of 66 cm: [+ 3.50 axis 90] and
[+ 4.25 axis 180]. What is the eyeglasses prescription?
A: Step 1: Subtract the working distance. In this case,
the working distance is 66 cm, which is equal to 1.50 D:
[+ 3.50 axis 90] - 1.50 = + 2.00 axis 90
[+ 4.25 axis 180] - 1.50 = + 2.75 axis 180
Step 2: Transpose from cross-cylinder notation to plus-
cylinder notation:
+ 2.00 sphere + ([+ 2.75 - 2.00] axis 180)
Objective prescription = +2.0 DS+ 0.75 DC x 180

Plus-Cylinder Technique
•If the second meridian is to be neutralized
with a plus-cylinder lens (as is done with a
plus-cylinder phoropter or loose lenses
and trial frames), the first spherical lens
should be left in the phoropter or trial
frames.Keeping the spherical lenses in
place. The axis of the cylindrical lens is
oriented in the direction of the axis of the
streak for the second meridian.

Plus-Cylinder Technique
•Because a cylinder lens is being used, no
power is being added along the axis of the
second meridian (which, of course,
corresponds to the power of the first
meridian).
•When the neutralization reflex is found for
the second meridian, the streak is rotated
90 degrees to ensure that the first
meridian is still neutralized.

Plus-Cylinder Technique
•The working distance is then subtracted from the
spherical lens only, and the spectacle prescription is
easily determined as follows:
• Q: A patient is neutralized with the following lenses
at a working distance of 66 cm: [+ 3.50 sphere] and
[+ 0.75 axis 180]. What is the eyeglasses prescription?
• A: Step 1: Subtract the working distance from the
spherical lens only. In this case, the working distance
is 66 cm, which is equal to 1.50 D:
[+ 3.50 sphere] - 1.50 = + 2.00 sphere
Step 2: Add the cylindrical lens to the new power of
the spherical lens:
+ 2.00 sphere + [+ 0.75 axis 180]
Objective prescription= 2.00 + DS + 0.75 DC x180

Minus-Cylinder Technique
• Some clinicians prefer to work in minus cylinder,
patients are neutralized in the same aforementioned
manner, except that the more “with” or less
“against” meridian is neutralized first with spherical
lenses.
• Then the less “with” or more “against” meridian is
neutralized with a minus-cylinder in much the same
way as the previous example used a plus-cylinder
lens.
•The transposition is done as follows:

Minus-Cylinder Technique
•Q: A patient is neutralized with the following
lenses at a working distance of 66 cm: [+ 4.25
sphere] and [-0.75 axis 90]. What is the
eyeglasses prescription?
A: Step 1: Subtract the working distance from
the spherical lens only. In this case, the working
distance is 66 cm, which is equal to 1.50 D:
)+ 4.25 -1.50 (= + 2.75 sphere
Step 2: Add the minus cylindrical lens to the
new power of the spherical lens:
•+ 2.75 sphere + (-0.75 axis 90(
90 × 0.75 - 2.75 + =

The next step is to neutralize the astigmatism
(with minus-cylinder power).
Remember that one meridian has already been
neutralized. The meridian 90 degrees away still
has with-motion. We begin by streaking this
meridian that has the brightest, narrowest with-
reflex.

Since we are using a minus-cylinder lens, we
will line up our cylinder axis perpendicular to
the orientation of the streak. In other words,
at 90 degrees in this example. We are
streaking the 90 degree meridian, and the
axis of the correcting minus-cylinder will be
90 degrees.

Once we have a neutral reflex, we have reached the
endpoint. Neutrality can be assumed when any with-
motion just disappears. This is preferable to relying
on recognizing a neutral reflex, because the reflex
may appear neutral over a wide range of power
settings.

The final step is to subtract for our
working distance. Lecture 6
•This is usually 1.50 D and it is subtracted from the
sphere power only. Suppose our phoropter reads
• -1.00-150x90 when we have finished neutralizing the
astigmatic meridian.
•We then would subtract 1.50 D sphere power for a
final retinoscopic estimate of -2.50-1.50x90.
• It is easiest to practice retinoscopy on younger
adults, ages 20 to 50. They usually have clear
media, relatively relaxed accommodation, and a
definite refractometric endpoint with which to
compare your retinoscopy.

RELIABILITY IJKLMNMOPQ
Because important therapeutic judgments may
depend on the retinoscopic measurements, it
is necessary to know how reliable these
measurements are. Reliability and precision
RSTUVgdgWXYgdgILKZare terms that describe the
degree to which repeated measurements
resemble one another. For example, five
repeated measurements for one patient
might yield the following five spherical
results: + 2.25, + 2.75, + 2.50, + 2.75, + 2.25.

RELIABILITY IJKLMNMOPQ
•With another examiner, the following values
might be found: + 1.75, + 2.50, + 3.25, + 2.75,
+ 2.25. The first examiner displaysزَ aرَ aبْرَأَ a ; ى دَ aبْرَأَ a a
higher degree of reliability or precision than
the second one. Nevertheless, the average
value is the same for both: + 2.50.
• If any single measurements had been
accepted as the patient's true refractive
error, the patient might have been misjudged
by only ¼D by the first examiner, but by as
much as ¾D by the second.

RELIABILITY IJKLMNMOPQ
•How is it possible, then, to judge the
reliability of any measurement? The answer
is straightforward: There must be repeated
measurements so that the variability of the
measurements can be assessed.
•The repeated measurements should be
independent of one another, each derived
without the measurer having knowledge of
what the preceding ones were.

RELIABILITY IJKLMNMOPQ
•These are usually called “replicate ىنث ;ى وط
measurements,” and there is no way to judge
reliability without them. In clinical practice,
we often do these replicate measurements
informally and almost intuitively.
•Fluctuations in the measurement process are
unavoidable; statisticians call them “error.”
•The second examiner in the previous
example is less precise than the first. She
showed greater variability and larger error.

Reliability
•Reliability and error for retinoscopy have
been evaluated. One study by Safir and
coworkers entailed five clinicians performing
retinoscopy on ten healthy young subjects
on two separate occasions separated by one
to three weeks. Results showed a 50%
probability that the two measurements of
spherical power would differ by 0.40 D.
•The Safir study also showed a threefold
difference in reliability among retinoscopists.

Accuracy
•Accuracy is another concept that is
important in the understanding of
measurement.
•Accurate measurements are those that
are close to the “true” value being
measured. Accuracy is a relative
conceptموهفم
• One procedure may be more or less
accurate than another.

•Suppose, for example, that a subject's true
spherical refractive error were 2.00 D, and
that ophthalmologist A measured it five times
as 2.25, 2.25, 2.00, 2.00, 1.75, whereas
ophthalmologist B got values of 2.5, 2.5, 2.75,
2.75, and 3. It is apparent that the method of
ophthalmologist A is more accurate than that
of ophthalmologist B.
•The typical measurement for ophthalmologist
A is closer to the quantity sought than that of
ophthalmologist B, even though the
precision WXYgdgILKZ of the two refractionists
is about the same. This example shows that
there is no predefined relationship between
precision and accuracy.

THE ROLE OF THE RETINOSCOPE IN A
MODERN EYE CLINIC-Autorefraction
•In the 21st century, we are faced with an
ever-more automated world, and the
ophthalmic practice has paralleled this move
toward automation. ىللا وأ ىتاموتلا ليغشتلا
• The retinoscope, really little more than a
light filament, lens, and mirror, is now joined
by many more sophisticated (and certainly
more expensive) devices developed to help
us obtain information regarding the refractive
state of our patients.

THE ROLE OF THE RETINOSCOPE IN A
MODERN EYE CLINIC-Autorefraction
•One family of such instruments consists of
the automated refractors—tabletop or hand-
held devices that perform an objective
refraction in a matter of seconds at the touch
of a button.
•The largest advantage of the automated
refractor is that clinic personnelنيفظوملا عومجم
who have almost no knowledge in the art of
refraction can use it. For the average patient,
automated refractors are reasonably
accurate when compared with the
retinoscope and generally agree within ½ D.

•Autorefraction
•If automated refractors errئطخي , they tend to
overestimate minus sphere by a fraction of a
diopter. This discrepancy ض قُضانت . ض رُضاعت
probably stems from the fact that patients
accommodate in response to their sense that
the automated refractor is at a closer
distance to the patient than is the 6 meter far
point used in retinoscopy. This is true even
though the devices are designed to relax
accommodation while fixing on an artificial
distant target.

Autorefraction
•Where the automated refractor is at an undeniable لا
دحَ aجْرَ يُض لا . ركَ aنْرَيُض disadvantage to the retinoscope is in
evaluating patients with irregular astigmatism, either
from pathology (e.g., keratoconus, pellucid marginal
degeneration) or postsurgically (e.g., corneal
transplant, laser in situ keratomileusis [LASIK]). All
the automated refractor operator can do is press a
button while having the patient fixate on the target.
•The automated refractor then either calculates a
“best fit” refraction or flashes an error message that
there too much irregular astigmatism exists to make
a reading.( Over cylinder)

Autorefraction
•The retinoscopist, however, can gain much more
information about the refractive state of the patient
by judging the quality of the light reflex observed in
the patient's pupil.
• A skilled retinoscopist usually can deduce
quantities and qualities of astigmatism in patients
for whom the automated refractor fails. This is
especially true in patients with poor best-corrected
visual acuity.
•Other instruments that must be compared with the
retinoscope are the keratoscope and the automated
corneal modeling systems. Although it is tempting to
compare these instruments with the retinoscope
because they each provide important information
regarding astigmatism,

Autorefraction
•it must be remembered that these
instruments serve different purposes within
the ophthalmic practice. The keratoscope
and corneal topographers are used to
evaluate corneal astigmatism only.
•The retinoscope, however, is used to
determine the entire refractive state of the
eye. These instruments all have their place
and can complementI?OTq each other well.

THE ROLE OF THE RETINOSCOPE IN A
MODERN EYE CLINIC-Autorefraction
•A final issue, one that is becoming more
important with every passing year, is the role
of the retinoscope in managing the refractive
surgery patient. Few studies address this
problem. Retinoscopy has been shown to be
accurate in evaluating the postoperative
patient. Anecdotally, I?]MT??`a?g:gI?]p^?i`a? we agree
with these results. In our practice, we rely
heavily on retinoscopy in evaluating pre- and
postoperative refractive surgery patients.

THE ROLE OF THE RETINOSCOPE IN A
MODERN EYE CLINIC-Autorefraction
•We believe that automated refractors cannot
accurately evaluate the refractive state of
someone with a surgically altered cornea and
therefore believe that they have no role in
providing data on these patients.
•Other studies have shown that corneal
topography alone is not adequate in
evaluating patient satisfaction after laser
refractive surgery.

THE ROLE OF THE RETINOSCOPE IN A
MODERN EYE CLINIC-Autorefraction
•Remembering that the critical zone of the
retinoscopy reflex is the central 3 mm, and
that the average excimer laser ablation
diameter is 6 mm, one can see that the
retinoscope is well suited to evaluate these
patients.
•When patients who had previously had
corneal refractive surgery subsequently
undergo cataract extraction with intraocular
lens (IOL) implantation, there is more
variability in the postoperative refractions
than for typical cataract patients.

THE ROLE OF THE RETINOSCOPE IN A
MODERN EYE CLINIC-Autorefraction
The IOL calculations rely not on retinoscopy
(objective refraction), but instead on
keratometry (corneal curvature) and a-scan
ultrasonography (axial length). One can only
wonder if the diagnostic procedure of choice
for these patients might someday be for the
surgeon to remove the cataract, perform
intraoperative retinoscopy of the aphakic
eye, calculate the necessary lens power, then
place the desired IOL implant.

THE ROLE OF THE RETINOSCOPE IN A
MODERN EYE CLINIC-Autorefraction
•In that way, the IOL would depend on
the patient's refractive state rather than
on artificial calculations based on the
patient's altered ocular anatomy.

Degrees of Astigmatism
Mild
Astigmatism
>1.00
diopters
Moderate
Astigmatism
1.00 to 2.00
diopters
Severe
Astigmatism
2.00 to 3.00
diopters
Extreme
Astigmatism
<3.00
diopters

Clinical classification of astigmatism
1.Regular astigmatism :in which the two principle
meridians are at right angle and is susceptible to
easy correction by cylindrical lenses.
2.Oblique astigmatism :in which the two principle
meridians are not at right angle but are crossed
obiquely,it is corrected by using
spherocylindrical lenses ,it is not very common.
3.Irregular astigmatism :where there are
irregularities in the curvature of the meridians so
that no geometrical figure is formed ,and the
correction is very difficult.

Types of astigmatism
1.Simple astigmatism :where one of
the foci falls upon the retina while
the other focus may fall in front or
behind the retina so that while one
meridian is emmetropic the other
meridian is either myopic or
hypermetropic .

Types of astigmatism
2.Compound astigmatism :where neither
of the two foci lies upon the retina but
both are placed in front of or behind
the retina on the same direction ,the
state of refraction is then entirely
myopic (compound myopic
astigmatism) or entirely hypermetropic
(compound hypermetropic
astigmatism) .

Types of astigmatism
3.Mixed astigmatism :where one focus is
in front of and the other is behind the
retina, so that the refraction is myopic
in one direction and hypermetropic in
the other .

Types of astigmatism

Split focus in astigmatism

Other classification
Direct astigmatism :when the
vertical curve is greater than the
horizontal curve.
Indirect astigmatism :when the
horizontal curve is greater than the
vertical curve .
B a c k

1.Patients with astigmatism have
blurred or distorted vision at all
distances.
2. It can also cause images to
appear doubled, particularly at
night.
3.Patients have difficult focusing
on various objects such as finely
printed words and lines.
4.Headache and fatigue of the
eye are common as the person
tends to strain his eyes.
5.Eye discomfort and irritation
are also frequent.
What are the general symptoms of
Astigmatism ?

Symptoms of low astigmatism
(>1.0D) include
1.Asthenopia {tired eyes},
especially when doing precise قيقِيقدَ a
work at a fixed distance.
2.Transient blurred vision relieved
by rubbing the eyes "as in
hyperopia" when doing precise
work at a fixed distance.
3.Frontal headaches with long
periods of visual concentration
on a task.

Symptoms of high astigmatism
(<1.0D) include
1.Blurred vision , asthenopia and frontal headache
are more severe than in low astigmatism
2.Tilting of the head for oblique astigmatism
3.Slinting to achieve "pinhole" vision clarity.
4.Reading material held close to eyes to achieve
large (as in myopia) but blurred retinal image.
5.The letters in the book appear as running
together i.e. getting mixed up.

Optical condition in astigmatism

Causes of Astigmatism
Heriditary :
•The exact cause remains unknown; however some
common types of astigmatism seem to run in
families and may be inherited.
• It is thought that most people have some form of
astigmatism as it is rare to find perfectly shaped
curves in the cornea and lens, but the defect is
rarely serious.
•The majority of these studies demonstrate an
autosomal (of asexual chromosomes )dominant form
of genetic transmission. Autosomal recessive
transmission has been shown occasionally. Rarely,
X-linked recessive form has also been reported.

Acquired causes of astigmatism
1.Diseases of the cornea result in its deformity; an
extreme example is seen in conical cornea
(keratoconus), while inflammations and ulceration of
the cornea produce corneal scar.
2.Traumatic interference with the cornea may bring about
the same result in this category we should include
surgical trauma, particularly operations for cataract.
Furthermore, corneal astigmatism can be induced by
the pressure of swellings of the lids, whether the
humble chalazion or a true neoplasm.
3.A transient deviation form normal can be produced by
finger pressure on the eye, by contraction of the lids
(blepharospasm ), or by the action of the extra-ocular
muscles.

Acquired causes of astigmatism
4.Curvature astigmatism of the lens also
occurs with great frequency. In great
majority of cases such anomalies are small;
but on occasion, as in lenticonus, they may
be marked.
5.Not uncommonly the lens is placed slightly
obliquely or out of line in the optical system
and this, causing a certain amount of
decentring, produces a corresponding
astigmatism;
6.A traumatic subluxation of the lens has
similar results

Keratoconus (KC)
Keratoconus is a
progressive disorder in which
the cornea assumes an
irregular conical shape. The
onset is at around puberty with
slow progression thereafter.
Though the ectasia may
become stationary at any time,
both eyes are affected, if only
topographically, in almost all
cases.

Keratoconus

Characteristics
INCIDENCE:
Keratoconus is bilateral in approximately 96% of cases. Typically,
one eye is affected earlier, and the disease progresses further
than in the fellow eye. Keratoconus is often diagnosed in
persons in their early teens to early twenties.
There does not appear to be a significant difference in the
incidence of keratoconus between left and right eyes nor
between male and female subjects.

Histopathologic changes
It is still unclear what causes the corneal
changes that occur in keratoconus. A triad of
classic histopathologic changes has been
observed:
1.Thinning of the corneal stroma.
2.Breaks in bowman's layer.
3.Iron deposition in the basal layers of the
corneal epithelium( Fleischer’s ring).

Etiology Of KC
1.Heredity
2.Eye rubbing and atopy
3.Contact lens wear
4.Abnormalities in ocular rigidity
and structure

Associations

Ocular associations include:
1.vernal keratoconjunctivities,
2. blue sclera,
3. aniridia,
4.ectopia lentis,
5.Leber congenital amaurosis and
6. retinitis pigmentosa.

predisposing factors
1. Rigid contact lens wear and
2. Constant eye rubbing have also
been proposed as predisposing
factors.

By keratometry keratoconus is
classified as mild (>48 D),
moderate (48- 54D) and severe
(<54D). Morphologically, the
following are the three types:
1.Nipple IO?U cones,
characterized by their small
size (5mm) and steep
curvature. The apical center is
often either central or
paracentral and displaced
inferonasally
Classification and progressionClassification and progression

2.Oval cones or
saggingىلّةدتي . يختري ,
which are larger than
the nipple form
equals
5-6mm, ellipsoidمٌ ناسَّم جَ a مُض
ص قِيقان and commonly
displaced
inferotemporally.
Classification and Classification and
progression progression

3.Globus cones,
which are the
largest < 6mm
and may involve
over 75 % of the
cornea.
Classification and Classification and
progression progression

Clinical picture/ symptoms
1.Presentation is with impaired vision in one eye
caused by progressive astigmatism and myopia.
2.The patient may report frequent changes in
spectacle prescription or decreased tolerance to
contact lens wear.
3.As a result of the asymmetrical nature of the
condition, the fellow eye usually has normal vision
with negligible astigmatism at presentation, which
however, increases as the condition progresses.

1.Direct ophthalmoscopy
2.Retinoscopy
3.Slitlamp biomicroscopy
4.Keratometry
5.Placido disc
6.Corneal topography
7.Videokeratoscopy signs
Clinical picture/DIAGNOSIS

Often subtle, can be detected
as follows:
1.Direct ophthalmoscopy
from a distance of one foot
shows an “oil droplet”
reflex
2.Retinoscopy shows an
irregular “scissor” reflex.
Clinical picture/ Early signs

Clinical picture/ Early signs
Slitlamp biomicroscopy
shows very fine,
vertical, deep stromal
striae ( vogt lines)
which disappear with
external pressure on
the globe.
Prominent corneal nerves
may also be present.

Clinical picture/ Early signs
Keratometry shows
irregular
astigmatism where
the principal
meridians are no
longer 90 degree
apart and the mires
cannot be
superimposed.

Videokeratoscopy signs:
1.Compression of mires in
affected region.
2.Color map showing
increased power in isolated
area of cone .
3.Inferior- superior dioptric
asymmetry.
Clinical picture/ Early signs

These devices are used to detect and
quantify corneal surface curvature and the
presence of astigmatism. A keratoscope
uses light to project rings on the cornea.
Observation through the keratoscope of
the reflection of light from the cornea
and inspection of the shape and spacing of
the rings provide information about the
degree of astigmatism.
Keratoscope and videokeratoscope

A keratoscope fitted with a video camera is
called a videokeratoscope.
A videokeratoscope is the most common
instrument used to quantify the change in
corneal surface curvature, in a process
called corneal topography.

Placido disk and keratoscope
•Photokeratoscopy, which employ optical
principles that are similar to those of the
keratometer, measure a larger surface
area and provide a more complete
appreciation of corneal shape.

Placido disk and keratoscope

Klein hand-held keratoscope and
Placido disk

Videokeratography of with-the-rule, against-the
rule, oblique regular astigmatism

Clinical picture/ Early signs
Corneal topography is
the most sensitive
method for
detecting very early
keratoconus.

Normal
cornea

Keratoconus
Suspect

Moderate
Keratoconus

Advanced
keratoconus

Large Inferior ConeSuperior cone Small nipple cone

Clinical picture/ Late signs
•Late signs:
1.Slit lamp shows:
Progressive corneal thinning, to as little
as one – third of normal thickness,
Marked increase of the depth of A C
2.Associated with poor visual acuity
resulting from marked irregular myopic
astigmatism with steep keratometry (k)
readings.
3.Bulging of the lower lid in down gaze
(Munson’s sign)

Clinical picture/ Late signs
4.Epithelial iron deposits
(Fleischer’s ring) may
surround the base of the
cone and are visualized
best with a cobalt blue
filter of the slit lamp
5.Stromal scarring in
severe cases.

Clinical picture/ Late signs
6.Acute hydrops is an acute influx
of aqueous in to the cornea as a
result of a rupture in descemet
membrane. This causes a sudden
drop in visual acuity associated
with discomfort and watering.
Although the break usually heals
within 6-10 weeks and the corneal
oedema clears, avariable amount of
stromal scarring may develop.

Clinical picture/ Late signs
Acute hydrops are initially
treated with hypertonic
saline and patching or a
soft bandage contact lens.
Healing may result in
improved visual acuity as
a result of scarring and
flattening of the cornea.
Keratoplasty should be
deferredئجري . لجِّؤي until
the oedema has resolved.

Differential diagnosis
1.Corneal Warpage جَ aوَّمعَ a Syndrome
2.High-riding rigid Gas-permeable lens
3.Keratoglobus

The topography of keratoconus: LECTURE 8The topography of keratoconus: LECTURE 8
The photokeratoscope or The photokeratoscope or placido discplacido disc can provide an can provide an
overview of the cornea and can show the relative overview of the cornea and can show the relative
steepness of any corneal area.steepness of any corneal area.
keratoconic corneakeratoconic cornea Normal corneaNormal cornea

EyeSys System
The corneal surface has 75% of the refractive or light
focusing ability of the eye. The EyeSys System
utilizes placido disk technology to acquire images of
the corneal surface. Placido disk technology is
based on a technique that captures the reflection of
rings of light off the surface of the cornea and
measures the different distances between the ring
reflections.
Current software technology captures the reflected
images with a digital camera, processes جلاعي . لماعيُ
the data, and displaysءادابْداإِب ; ة نَةابَةإِب the information in
multiple formats.

A Placido device is made up
of many concentric light rings.
The exact arrangement and
number of rings may vary with
different manufacturers
Light rings are projected on the
cornea above.This image is
captured and analyzed as
thousands of computations are
performed instantly.

corneal topography
ف شِف كْشِتَكْسْشِمُس ; فاف شَّاكَكْ

•The map above was taken prior to simulated
treatment. The horizontal red and orange areas are
elevated above the cooler colors green blue areas
demonstrating this patient’s against the rule
astigmatism.

corneal topography
•The same map is below after LASIK simulated laser
treatment. Observe the more uniform neutral green
color centrally indicating a much smoother uniform
surface without astigmatism (corrected with
LASIK).

Photokeratoscopy view of early keratoconus
Note the pear-shaped لكشلا يرثمك pulling of
the central keratoscopy mires. The close
proximity of the rings (in the inferior-temporal
portion of the eye(
indicates corneal steepening
and greater distance between the rings
(in the superior-nasal portion of the eye(
indicates flattening.

corneal topography

•The typical spiral pattern of keratoconus
progression. The condition commonly begins in
the inferior-temporal quadrant, with the last area
of the cornea to be topographically affected in
the superior-nasal quadrant.
•In color-coded topographic images, red
represents steeper corneal curvature, and the
spectrum of yellow, green, and blue represents
progressively flatter curvatures.

corneal topography
•The nipple-shaped form of
keratoconus
demonstrates a small
central ectasis
surrounded by 360
degrees of “normal”
cornea.

corneal topography
The most striking features of the nipple topography
are:
•The often high degree of with-the-rule corneal
toricity confined to the central 5.0 mm of the cornea.
•The nearly 360 degrees of “normal” mid-peripheral
cornea that surrounds the base of the cone.
•The occasional presence of an elevated fibroplastic
nodule ة نَةرَةدَة at the apex of the cornea, hence the
name nipple keratoconus. The superficial nodules
are frequently erodedتّ حُيَة . لكّ أتي by the presence of
a rigid contact lens, often necessitating: rigid gas
permeable/soft contact lens (RGP/SCL( or
piggyback designs,

corneal topography
Nipple-shaped keratoconus may also manifest as a small
central ectasia with moderate to high with-the-rule corneal
astigmatism in the form of regular bow tie.

corneal topography
Oval-shaped keratoconus is hallmarked
by steepening of the inferior cornea

Globus-Shaped Topography
•The globus form of keratoconus affects the
largest area of the cornea, often encompassing
nearly three quarters(75%) of the corneal
surface.
• Due to its size, nearly all of the keratoscopy
rings will be encompassedن wمَّاضَكْ مُس ; لولمُسشْشِمَكْ within
the area of the ectasia. Unlike the advanced
forms of nipple or oval keratoconus, the globus
cone has no island of “normal” mid-peripheral
cornea above or below the midline.

Globus-Shaped Topography
Due to the size of the globus-shaped keratoconus, all
nine rings of the photokeratoscopy image are
encompassed by the conical area and no “islands”
of normal mid-peripheral cornea are seen.

Normal corneal topography
Five qualitative patterns of
normal corneal topography
using a normalized scale.
Top left, round; top center,
oval; top right, symmetric
bow-tie; bottom left, =
asymmetric bow tie;
bottom center, irregular. In
the normalized scale
(bottom right( the range of
dioptric power represented
by each color varies among
eyes, depending on the
degree of corneal
asphericity. Classification
of normal corneal
topography basedon computer-assisted videokeratography.

Keratoconus topography
•Videokeratographs mirror this distortion by
producing mires that are typically oval. The
distance between rings is smallest at the
steepest corneal slope and farthest apart
superiorly where the cornea is flattest.
•Tangential curvature maps of projection-based
systems provide additional information. On
these maps the steepest slope is easily located
as being inferior to the apex, producing an
asymmetric bow tieلكشلا يّ شِب ارفَة ة بقر طابر . This
corresponds to the exaggerated prolateلواطتم
shape of the keratoconic eye.
• Projection-based systems can be used to
locate the apex of the cone on elevation maps
as the highest point.

Axial map
•Axial map. Also called the "power" or
"sagittal" map, this output is the simplest
of all the topographical displays. It shows
variations in corneal curvature as
projections ةشاف شلا ىلع ةكرحتملا رولصلا ضرع
and uses colors to represent dioptric
values. Warm colors such as red and
orange show steeper areas; cool colors
such as blue and green denote the flatter
areas.

Sometimes referred to as the instantaneous ىروف، ىوتوى ،فورى
ىظحل , local, or "true" map, it also displays the cornea
as a topographical illustration, using colors to
represent changes in dioptric value. However, the
tangential strategy bases its calculations on a
different mathematical approach that can more
accurately determine the peripheral corneal
configuration.
Tangential يّ سّ امَ مُmap

Tangential map
•It does not assume the eye is spherical, and
does not have as many presumptionsضرْشِفَكْ as
the axial map regarding corneal shape.
•In fact it is the map that more closely represents
the actual curvature of the cornea over the axial
map. The tangential map recognizes sharp
power transitions more easily than the axial
map, and eliminates the "smoothing"
appearance that appears on the axial map.

This utilizes yet another algorithm to give additional
information about the cornea. An elevation map shows
the measured height from which the corneal curvature
varies (above or below) from a computer-generated
reference surface. Warm colors depict . .
فصِ ي روّ صي مسري

points that are higher than the reference surface; cool
colors designate lower points.
This map is most useful in predicting fluorescein
patterns with rigid lenses. Higher elevations (reds)
represent potential areas of lens bearing, while the
lower areas (greens) will likely show fluorescein
pooling.
Elevation map.

Elevation map

Normal
cornea

Keratoconus
Suspect

Early Keratoconus

Progressive Nipple Keratoconus

Moderate Oval
Keratoconus

Globus keratoconus

Advanced Globus keratoconus

corneal topography
•Corneal topography and imaging.
Symmetric bow tie typical for regular
astigmatism.

corneal topography
•This elevation map shows inferior thinning
in a patient's left eye.

Treatment Of
keratoconus
Non-
surgical
Surgical
Spectacles
Contact lenses
Penetrating
Keratoplasty
Lamellar
Keratoplasty
Lamellar
keratoplasty
Intracorneal rings
Other Surgery
C3RC3R

Treatment that prevent Treatment that prevent
progression of KCprogression of KC
Collagen cross linking treatments (C3RCollagen cross linking treatments (C3R))
Recent treatment which is based on strengthen Recent treatment which is based on strengthen
the cross-linking of corneal collagen by utilizes the cross-linking of corneal collagen by utilizes
riboflavin and ultraviolet (UV) light exposureriboflavin and ultraviolet (UV) light exposure. .
During the 30-minute riboflavin eyedrops are During the 30-minute riboflavin eyedrops are
applied to the cornea, which are then activated applied to the cornea, which are then activated
by a UV light. This is the process that has been by a UV light. This is the process that has been
shown in laboratory and clinical studies to shown in laboratory and clinical studies to
increase the amount of collagen cross-linking in increase the amount of collagen cross-linking in
the cornea and strengthen the corneathe cornea and strengthen the cornea..

Collagen cross linking treatments causes the Collagen cross linking treatments causes the
collagen fibers to thicken, stiffen, crosslink & collagen fibers to thicken, stiffen, crosslink &
re-attach to each other, making the cornea re-attach to each other, making the cornea
stronger and more stable thus convincingly stronger and more stable thus convincingly
halting the progression of the disease. The halting the progression of the disease. The
figures below demonstrate almost 10 diopters figures below demonstrate almost 10 diopters
of corneal flattening in one patient before (left) of corneal flattening in one patient before (left)
after this combined treatment (rightafter this combined treatment (right).).

Advantages of Advantages of
C3RC3R::
..Simple one time treatmentSimple one time treatment
2.2.No periodic treatments requiredNo periodic treatments required
3.3.Halts the progress and causes some Halts the progress and causes some
regressionregression
4.4.It is permanentIt is permanent
5.5.No handling of lenses every dayNo handling of lenses every day
6.6.Does not need any eye donationDoes not need any eye donation
7.7.No precautionNo precaution
8.8.No injectionNo injection
9.9.No stitches as in keratoplastyNo stitches as in keratoplasty
10.10.No incisions as in IntacsNo incisions as in Intacs
1.1.Quick recovery, short follows upQuick recovery, short follows up

spectacle lensesspectacle lenses
As keratoconus progresses, As keratoconus progresses, spectacle lensesspectacle lenses often fail to often fail to
provide adequate visual acuityprovide adequate visual acuity::
1.1. Especially Especially at night.at night.
2.2.This can be further complicated by the fact that the This can be further complicated by the fact that the
patient's glasses prescription may patient's glasses prescription may change frequentlychange frequently due due
to the disease progress and can be limited by the degree to the disease progress and can be limited by the degree
of of myopia and astigmatismmyopia and astigmatism that must be corrected. that must be corrected.
3.3.Also, keratoconus is often asymmetric therefore full Also, keratoconus is often asymmetric therefore full
spectacle correction may be intolerable because of spectacle correction may be intolerable because of
anisometropia and aniseikoniaanisometropia and aniseikonia. .
However, despite these limitations, spectacles can often However, despite these limitations, spectacles can often
provide surprisingly good visual results in the provide surprisingly good visual results in the early stagesearly stages
of the condition.of the condition.

contact lenses
Contact lens options for keratoconusContact lens options for keratoconus
•When a keratoconic patient is no longer able to When a keratoconic patient is no longer able to
obtain good visual acuity with spectacle lenses obtain good visual acuity with spectacle lenses
because of increasing levels of irregular myopic because of increasing levels of irregular myopic
astigmatism and higher-order aberrations, rigid astigmatism and higher-order aberrations, rigid
contact lenses will be required, effectively to contact lenses will be required, effectively to
provide a new anterior surface to the eye. provide a new anterior surface to the eye.
•Contact lenses are considered when vision is Contact lenses are considered when vision is
not correctible to 6/9 by spectaclesnot correctible to 6/9 by spectacles and patients and patients
become symptomatic.become symptomatic.

contact lenses
The successful fitting of contact lenses for The successful fitting of contact lenses for
keratoconus requires that three objectiveskeratoconus requires that three objectivesفادهأفادهأ
be met :be met :
1.1.The lens-to-cornea fitting relationship should The lens-to-cornea fitting relationship should
create the least possible physicalcreate the least possible physical trauma trauma to the to the
cornea. cornea.
2.2.The lens should provide The lens should provide stable visual acuitystable visual acuity
throughout the patient's entire wearing throughout the patient's entire wearing
schedule. schedule. لَكْوَكْدْشِجَكْلَكْوَكْدْشِجَكْ
3.3.The lens should provide The lens should provide all day wearing comfort.all day wearing comfort.

Lens Designs for KeratoconusLens Designs for Keratoconus
Soft lensesSoft lenses
Soft lenses have a limited role in correcting corneal Soft lenses have a limited role in correcting corneal
irregularity, as they tend to drapeirregularity, as they tend to drapeىلع لّ داَةتمىلع لّ داَةتم over the over the
surface of the cornea and result in poor visual surface of the cornea and result in poor visual
acuity .acuity .
Hence, soft lenses are used only in the Hence, soft lenses are used only in the early early
stages of the diseasestages of the disease. In such cases, the lenses . In such cases, the lenses
are usually toric, and are fitted in the same are usually toric, and are fitted in the same
manner, as they would be on a patient with manner, as they would be on a patient with
myopic astigmatism. The fitting procedure begins myopic astigmatism. The fitting procedure begins
by placing a soft lens with powers equal to the by placing a soft lens with powers equal to the
manifest refraction vertexed manifest refraction vertexed ة مقلا ىلعto the plane of to the plane of
the cornea on the eye. Final lens power is best the cornea on the eye. Final lens power is best
calculated by performing a sphero-cylinder calculated by performing a sphero-cylinder
refraction. refraction.

Toric soft contact lenses for early Toric soft contact lenses for early
KCKC

soft contact lenses for early KCsoft contact lenses for early KC
•However, some hydrogel lenses have been designed However, some hydrogel lenses have been designed
specially for keratoconus. specially for keratoconus. Hydrogel lenses are made
relatively large in diameter, usually 13.5 to 14.5 mm in
diameter which results in the lens edge being beyond the
limbus on the sclera.
• They are designed to be thicker than regular soft lenses They are designed to be thicker than regular soft lenses
so they retain a rigid shape to some extent. For this so they retain a rigid shape to some extent. For this
reason they compress the central cornea and partially reason they compress the central cornea and partially
trap a trap a tear pooltear pool, as with rigid corneal lenses. In effect, , as with rigid corneal lenses. In effect,
they are rigid lenses made from hydrogel materials, and they are rigid lenses made from hydrogel materials, and
they do appear to be giving a reasonable visual result they do appear to be giving a reasonable visual result
with some types of keratoconuswith some types of keratoconus. .

HYDROGEL (SOFT) LENSES
•Hydrogel lenses increase the amount of oxygen
reaching the cornea as do most contact lenses.
By making
the lenses thinner or increasing the water
content, or both, more oxygen will reach the
cornea. It is not uncommon to have hydrogel
lenses made as thin as 0.035 mm.
•Lenses are available up to about 75% water
content with most lenses being used today
range from 38% to 65% water .
Thick
Thin

soft contact lenses for early KCsoft contact lenses for early KC
Criteria to useCriteria to use::
..One criterion to use to determine if soft One criterion to use to determine if soft
lenses are acceptable is that they should lenses are acceptable is that they should
induce no scarring. Often, soft contact induce no scarring. Often, soft contact
lenses lead to repeated corneal lenses lead to repeated corneal
abrasions, which can result in scarring.abrasions, which can result in scarring.
2.2. Another criterion is the patient must be Another criterion is the patient must be
happy with his vision and is able to happy with his vision and is able to
function properly in their daily activities.function properly in their daily activities.

soft contact lenses for early KCsoft contact lenses for early KC
Advantages Advantages
1) They afford higher levels of 1) They afford higher levels of comfortcomfort and and
longer wearing times, especially in longer wearing times, especially in
patients intolerant to RGP corneal lenses patients intolerant to RGP corneal lenses
or in monocular keratoconus.or in monocular keratoconus.
2) They are useful where the cone apex 2) They are useful where the cone apex
may be may be displaceddisplaced, especially if it is very , especially if it is very
low.low.
3) They are relatively 3) They are relatively simple to fitsimple to fit. .

soft contact lenses for early KCsoft contact lenses for early KC
DisadvantagesDisadvantages
1) Visual acuity may be variable (less corrected) in 1) Visual acuity may be variable (less corrected) in
cases of very high minus lenses.cases of very high minus lenses.
2) Low-powered 2) Low-powered diagnosticdiagnostic lenses may not provide lenses may not provide
an accurate guide to the fit of the an accurate guide to the fit of the final lensfinal lens, ,
which may be extremely high powered.which may be extremely high powered.
3) If the condition (KC) has progressed, it may be 3) If the condition (KC) has progressed, it may be
difficult to change to RGP lenses at a later difficult to change to RGP lenses at a later
stage. stage.

Rigid gas permeable lensesRigid gas permeable lenses
Rigid gas permeable (RGP) corneal lenses are the Rigid gas permeable (RGP) corneal lenses are the
lenses of first choice for correcting keratoconus. lenses of first choice for correcting keratoconus.
They provide the best possible vision with the They provide the best possible vision with the
maximum comfort so that the lenses can be worn maximum comfort so that the lenses can be worn
for a long period of timefor a long period of time. .
The purpose of the lens is to cover the irregular The purpose of the lens is to cover the irregular
astigmatism and the disordered anterior surface astigmatism and the disordered anterior surface
optics of an ectatic cornea by providing a regular, optics of an ectatic cornea by providing a regular,
spherical, optic surface before the eye (Figure spherical, optic surface before the eye (Figure
below). The lens does not retard the progression below). The lens does not retard the progression
of the diseaseof the disease..

Rigid gas permeable lensesRigid gas permeable lenses

RGP contact lenses are primary RGP contact lenses are primary
option for correcting KC visionoption for correcting KC vision
Keratoconic cornea
RGP
lens

Piggyback Soft LensesPiggyback Soft Lenses
•The technique of placing a rigid contact lens on top of The technique of placing a rigid contact lens on top of
a soft lens (piggyback) was first described in the mid a soft lens (piggyback) was first described in the mid
1970’s. Early piggyback systems consisted of thick, 1970’s. Early piggyback systems consisted of thick,
low Dk, soft lenses in combination with low Dk low Dk, soft lenses in combination with low Dk
silicone/acrylate rigid lenses. It was not surprising that silicone/acrylate rigid lenses. It was not surprising that
this combination frequently resulted in corneal hypoxia this combination frequently resulted in corneal hypoxia
and neovascularisation, which limited its usefulness. and neovascularisation, which limited its usefulness.
However, with the recent introduction of high Dk However, with the recent introduction of high Dk
silicone hydrogel lenses and stable high Dk GP silicone hydrogel lenses and stable high Dk GP
materials, the dual lens system is now enjoying a materials, the dual lens system is now enjoying a
rebirth, particularly for keratoconus patients rebirth, particularly for keratoconus patients
experiencing comfort or lens position issueexperiencing comfort or lens position issueذ فَكْنفمَكْ . ج رَكْخرمَكْذ فَكْنفمَكْ . ج رَكْخرمَكْ
..

Flexlens Piggyback lensFlexlens Piggyback lens

A recent piggyback lens system forA recent piggyback lens system for keratoconus keratoconus
consisting of a high Dk soft lens and an RGP lens consisting of a high Dk soft lens and an RGP lens
combinationcombination..
A rigid lens riding piggyback over a soft lens.

Scleral lensesScleral lenses
•Scleral lenses play a very significant role Scleral lenses play a very significant role
in cases of advanced keratoconus where in cases of advanced keratoconus where
corneal lenses do not work and corneal corneal lenses do not work and corneal
surgery is contra-indicated. Scleral surgery is contra-indicated. Scleral
lenses completely neutralize any corneal lenses completely neutralize any corneal
irregularity and can help patients irregularity and can help patients
maintain a normal quality of life. These maintain a normal quality of life. These
are large diameter lenses (23-25mm) are large diameter lenses (23-25mm)
that rest on the sclera, and vaults over that rest on the sclera, and vaults over
the cornea .the cornea .

A scleral and a corneal lens to A scleral and a corneal lens to
compare the sizecompare the size..
Because of their size, they do Because of their size, they do
not fall out; dust or dirt not fall out; dust or dirt
particles cannot get behind particles cannot get behind
them during wear. They are them during wear. They are
surprisingly comfortable to surprisingly comfortable to
wear because the edges of wear because the edges of
the lens rests above and the lens rests above and
below the eye lid margins so below the eye lid margins so
there is no lens awareness. there is no lens awareness.
The introduction of rigid gas The introduction of rigid gas
permeable (RGP( materials permeable (RGP( materials
has made this design more has made this design more
readily availablereadily available..

Scleral lensesScleral lenses
AdvantagesAdvantages
1.1.Comfortable to eyes.Comfortable to eyes.
2.2.Any type of corneal irregularity is corrected.Any type of corneal irregularity is corrected.
3.3.Easy to store.Easy to store.
4.4.Long life.Long life.
DisadvantagesDisadvantages
..Much chair time is needed.Much chair time is needed.
2.2.A very specialized fitting techniqueA very specialized fitting technique .

Rose K lensRose K lens
•The Rose K lens is probably the most widely The Rose K lens is probably the most widely
fitted keratoconus lens worldwide and achieves fitted keratoconus lens worldwide and achieves
an 85% first fit success in the UK. The Rose K an 85% first fit success in the UK. The Rose K
lens design is a lens design is a fully flexible lensfully flexible lens that works well that works well
on on early to advanced keratoconus patientsearly to advanced keratoconus patients . .
Complex lens geometry, combined with the Complex lens geometry, combined with the
enhanced material benefits makes the Rose K enhanced material benefits makes the Rose K
lens the good fit enhancing patient comfort and lens the good fit enhancing patient comfort and
visual acuity. Multiple parameters make fitting visual acuity. Multiple parameters make fitting
the Rose K lens possible for most keratoconic the Rose K lens possible for most keratoconic
eyes. The design starts with a standard 8.7mm eyes. The design starts with a standard 8.7mm
diameter and works by decreasing the optic diameter and works by decreasing the optic
zone diameter as the base curve gets steeperzone diameter as the base curve gets steeper..

Rose K™Rose K™ contact lens with small contact lens with small
optic zoneoptic zone

The Rose K™ lensThe Rose K™ lens
Rose K lensRose K lens

Rose K lensRose K lens
Rose K™ contact lens with large optic zoneRose K™ contact lens with large optic zone

The Rose K™ lensThe Rose K™ lens
AdvantagesAdvantages::
. Its complex geometry can be customized to suit . Its complex geometry can be customized to suit
each eye and can correct all of the myopia and each eye and can correct all of the myopia and
astigmatism associated with keratoconus. astigmatism associated with keratoconus.
2. They are easy to insert, remove and clean .2. They are easy to insert, remove and clean .
3. They provide excellent health to the eye, 3. They provide excellent health to the eye,
because they allow the cornea to "breath" because they allow the cornea to "breath"
oxygenoxygen directly through the lens. directly through the lens.
4. Practitioners have the Rose K™ trial set fitting 4. Practitioners have the Rose K™ trial set fitting
system which achieves a first fit system which achieves a first fit successsuccess in over in over
80% of patients' internationally80% of patients' internationally

surgical procedures
INTACS
Penetrating keratoplasty
Lamellar keratoplasty
Epikeratophakia
 Thermokeratoplasty

Treatment & Management
Intrastromal Ring (Intacs®(Intrastromal Ring (Intacs®(
•Definition: Intacs® were originally designed Definition: Intacs® were originally designed
and FDA approved in 1999 to correct mild and FDA approved in 1999 to correct mild
nearsightedness (myopia(. In patients with nearsightedness (myopia(. In patients with
keratoconus, Intacs® are indicated to reduce keratoconus, Intacs® are indicated to reduce
myopia and astigmatism in those who are no myopia and astigmatism in those who are no
longer able to achieve adequate vision with longer able to achieve adequate vision with
contact lenses or glasses.contact lenses or glasses. Intacs are indicated Intacs are indicated
for contact lens intolerant patients with for contact lens intolerant patients with
keratoconus who have minimal central stromal keratoconus who have minimal central stromal
scarring.scarring.

Intacs® are tiny (0.25mms thick( acrylic Intacs® are tiny (0.25mms thick( acrylic
ring segmentsring segments

Intrastromal Ring (IntacsIntrastromal Ring (Intacs®(®(
•They are an effective way to manage the They are an effective way to manage the
condition and restore functional acuity by helping condition and restore functional acuity by helping
to restore the natural shape of a cornea to restore the natural shape of a cornea
weakened by keratoconus. weakened by keratoconus.
•In a number of patients, Intacs® may delay or In a number of patients, Intacs® may delay or
ultimately prevent the need for corneal ultimately prevent the need for corneal
transplantation. A small incision is made in the transplantation. A small incision is made in the
periphery of the cornea and two thin arcs of periphery of the cornea and two thin arcs of
polymethyl methacrylatepolymethyl methacrylate slid slid قلزنفيقلزنفي between the between the
layers of the corneal layers of the corneal stromastroma, the incision then , the incision then
being closed. being closed.
•The segments push out against the curvature of The segments push out against the curvature of
the cornea, flattening the peak of the cone and the cornea, flattening the peak of the cone and
returning it to a more natural shape. returning it to a more natural shape.

The procedure, carried out on an outpatient basis under The procedure, carried out on an outpatient basis under
local anesthesialocal anesthesia, offers the benefit of being reversible and even , offers the benefit of being reversible and even
potentially exchangeable as it involves no removal of eye tissuepotentially exchangeable as it involves no removal of eye tissue

Intrastromal Ring (IntacsIntrastromal Ring (Intacs®(®(
•The inserts are designed to be placed at a depth of The inserts are designed to be placed at a depth of
approximately two-thirds the corneal thickness and approximately two-thirds the corneal thickness and
are surgically inserted through a small radial incision are surgically inserted through a small radial incision
into a troughinto a troughىرجم . ةاف نفقىرجم . ةاف نفق created within the corneal created within the corneal
stroma. The inserts shorten the corneal arc length stroma. The inserts shorten the corneal arc length
and have a net effect of flattening the central cornea.and have a net effect of flattening the central cornea.
• The amount of flattening is determined by the The amount of flattening is determined by the
insert's thickness. Rings are available in thicknesses insert's thickness. Rings are available in thicknesses
of 0.25, 0.275, 0.3, 0.325 and 0.35 mm and are of 0.25, 0.275, 0.3, 0.325 and 0.35 mm and are
oriented horizontally in the cornea at 3 and 9 o'clock. oriented horizontally in the cornea at 3 and 9 o'clock.

Intacs® - Clinical FactsIntacs® - Clinical Facts
•Clinical studies on the effectiveness of Clinical studies on the effectiveness of
intrastromal rings on keratoconus are in their intrastromal rings on keratoconus are in their
early stages, and results have so far been early stages, and results have so far been
generally encouraging, though they have yet to generally encouraging, though they have yet to
enter into wide acceptance with all refractive enter into wide acceptance with all refractive
surgeons. surgeons.
•In comparison with a penetrating keratoplasty, In comparison with a penetrating keratoplasty,
the requirement for some vision correction in the the requirement for some vision correction in the
form of hydrophilic (soft) contact lenses or form of hydrophilic (soft) contact lenses or
spectacles may remain subsequent to the spectacles may remain subsequent to the
Intacs® Intacs® operation.operation.

Intacs® - Clinical FactsIntacs® - Clinical Facts
Potential complications of intrastromal rings Potential complications of intrastromal rings
include :include :
..accidental penetration through to the accidental penetration through to the
anterior chamber when forming the anterior chamber when forming the
channel.channel.
2.2. post-operative post-operative infectioninfection of the cornea. of the cornea.
3.3. migration or extrusion of the segments. migration or extrusion of the segments.

Intacs® - Clinical FactsIntacs® - Clinical Facts
•Thousands of keratoconus eyes have been Thousands of keratoconus eyes have been
treated successfully with Intacs®. Most treated successfully with Intacs®. Most
patients have experienced better quality of life, patients have experienced better quality of life,
improved visual quality and stabilization of the improved visual quality and stabilization of the
keratoconic condition. The rings offer a good keratoconic condition. The rings offer a good
chance of vision improvement even in chance of vision improvement even in
otherwise hard to manage eyes, but it is not otherwise hard to manage eyes, but it is not
guaranteed and in a few cases may worsen.guaranteed and in a few cases may worsen.
•Considerable research has been collected on Considerable research has been collected on
patients having undergone the surgery since patients having undergone the surgery since
l97 as demonstrated by the following results:l97 as demonstrated by the following results:

Intrastromal Ring (IntacsIntrastromal Ring (Intacs®(®(
IMPROVED VISION :IMPROVED VISION :
•71% gained 71% gained 1 or more lines1 or more lines of Best Corrected of Best Corrected
Visual Acuity. Visual Acuity.
•73% gained 73% gained 2 or more lines2 or more lines in Uncorrected in Uncorrected
Visual Acuity. Visual Acuity.
•Eyes with worse preoperative acuity had Eyes with worse preoperative acuity had
greater improvements in greater improvements in postoperativepostoperative acuity. acuity.
•Eyes with Eyes with corneal scarringcorneal scarring also showed some also showed some
improvementimprovement

Intacs® - Clinical FactsIntacs® - Clinical Facts
SAFETY:SAFETY:
•Intacs® for keratoconus mirror the safety of FDA-Intacs® for keratoconus mirror the safety of FDA-
approved Intacs® for Myopia. approved Intacs® for Myopia.
•If required, Intacs® can be removed preserving the If required, Intacs® can be removed preserving the
option for corneal transplantation. option for corneal transplantation.
STABILIZED VISION:STABILIZED VISION:
•Intacs® may restore functional vision by allowing Intacs® may restore functional vision by allowing
the eye to be effectively corrected with contact the eye to be effectively corrected with contact
lenses or glasses besides intacs if needed.lenses or glasses besides intacs if needed.
•Intacs® flatten and shift the cone centrally, Intacs® flatten and shift the cone centrally,
restructuring the corneal architecture to a normal restructuring the corneal architecture to a normal
prolate shape.prolate shape.
•Intacs® add structural integrity Intacs® add structural integrity ة ملسة ملس to the cornea to the cornea
without invading the opticalwithout invading the optical zonezone .

Corneal topography before and after Corneal topography before and after
Intacs® insertionIntacs® insertion

Penetrating KeratoplastyPenetrating Keratoplasty
Lecture 10Lecture 10
Since the l50’s, penetrating keratoplasty has Since the l50’s, penetrating keratoplasty has
been the primary surgical procedure for been the primary surgical procedure for
treatment of keratoconus. A corneal treatment of keratoconus. A corneal
transplant,transplant, also known as a also known as a corneal graftcorneal graft, or , or
as a as a penetrating keratoplastypenetrating keratoplasty, involves the , involves the
removal of the central portion (called a removal of the central portion (called a
button) of the diseased cornea and replacing button) of the diseased cornea and replacing
it with a matched donor button of cornea.it with a matched donor button of cornea.

Penetrating keratoplasty for Penetrating keratoplasty for
treatment of keratoconustreatment of keratoconus..
Donated button
Patient’s corneal
rim

penetrating keratoplastypenetrating keratoplasty
IndicationsIndications
The primary indications for penetrating keratoplasty in patients The primary indications for penetrating keratoplasty in patients
with keratoconus are :with keratoconus are :
1.1.contact lens intolerance,contact lens intolerance,
2.2. progression of cone toward the corneal limbus,progression of cone toward the corneal limbus,
3.3. in severe cases, threatened corneal perforationin severe cases, threatened corneal perforation. .
4.4. Uncomplicated corneal hydrops.Uncomplicated corneal hydrops.
5.5.If the contact lenses fail to provide adequate visual If the contact lenses fail to provide adequate visual
acuity due to corneal scarring. acuity due to corneal scarring.
6.6.Sharp bilateral visual acuity is required for Sharp bilateral visual acuity is required for
recreational recreational يّ مِبامَةجْدا تِبسْدا اِبيّ مِبامَةجْدا تِبسْدا اِب or professional requirements.or professional requirements.

Penetrating Keratoplasty Surgical techniques Penetrating Keratoplasty Surgical techniques
The figures from below illustrate the procedureThe figures from below illustrate the procedure
This technique is suitable when disease A circular cut is made into This technique is suitable when disease A circular cut is made into
through the full thickness of the cornea. the diseased corneathrough the full thickness of the cornea. the diseased cornea

Penetrating KeratoplastyPenetrating Keratoplasty
The diseased cornea isThe diseased cornea is
removedremoved
A A healthy cornea ishealthy cornea is
transplantedtransplanted

The cornea transplant is held inThe cornea transplant is held in place with ultra-fine sutures. These place with ultra-fine sutures. These
are not visible to the naked eye. The transplant bonds slowly to the are not visible to the naked eye. The transplant bonds slowly to the
patient’s cornea and the sutures are then removedpatient’s cornea and the sutures are then removed..

Penetrating KeratoplastyPenetrating Keratoplasty
Post operative carePost operative care
•The healing process following transplant is long, The healing process following transplant is long,
often taking a year or longer. The time from often taking a year or longer. The time from
surgery to the removal of the stitches is surgery to the removal of the stitches is
commonly 6 to 17 months.commonly 6 to 17 months.
•The patient may be on steroid drops for months.The patient may be on steroid drops for months.
• Initially following surgery the donor button is Initially following surgery the donor button is
swollen and even following healing the button is swollen and even following healing the button is
usually thicker than the corneal bed in which it usually thicker than the corneal bed in which it
rests. A thick white ring of scarring between the rests. A thick white ring of scarring between the
donated button and the patient's outer cornea is donated button and the patient's outer cornea is
performed. performed.
•The white radial marks are where stitches were The white radial marks are where stitches were
placed to hold the transplant in position.placed to hold the transplant in position.

Penetrating KeratoplastyPenetrating Keratoplasty
Graft rejection reactions occur in 1% to 18% of Graft rejection reactions occur in 1% to 18% of
the patients. Signs of graft rejection include:the patients. Signs of graft rejection include:
1.1. ciliary's flush. ciliary's flush.
2.2.anterior chamber flare. anterior chamber flare.
3.3.keratic precipitates.keratic precipitates.
4.4.KhodaoustKhodaoust line and Krachmer's spots. Signs line and Krachmer's spots. Signs
of graft rejection are reported to occur from 1 of graft rejection are reported to occur from 1
month to 5 years following surgery. The month to 5 years following surgery. The
rejection rate for bilateral grafts is higher than if rejection rate for bilateral grafts is higher than if
only only one eye is graftedone eye is grafted. In the . In the bilateral bilateral
casescases, when a rejection reaction occurs it is , when a rejection reaction occurs it is
commonly in both eyes. commonly in both eyes.

Uveitis

Keratic precipitates

Penetrating KeratoplastyPenetrating Keratoplasty
•If the second eye is to be grafted, there is If the second eye is to be grafted, there is
usually a period of at least one year between usually a period of at least one year between
grafts. If signs of rejection occur, aggressive grafts. If signs of rejection occur, aggressive
treatment with steroids is begun. treatment with steroids is begun.
•Usually the reaction is overcome and the graft Usually the reaction is overcome and the graft
remains clear. Over 90% of the corneal grafts remains clear. Over 90% of the corneal grafts
are successful with some studies reporting are successful with some studies reporting
97% to 99% success rates at 5 and 10 years.97% to 99% success rates at 5 and 10 years.

Penetrating KeratoplastyPenetrating Keratoplasty
•Large amounts of astigmatism are common Large amounts of astigmatism are common
following keratoplasty. One study found an following keratoplasty. One study found an
average of 5.56 DC with a range from 0 to 17 D average of 5.56 DC with a range from 0 to 17 D
following suture removal, with other studies following suture removal, with other studies
showing an average of 5.4 DC .showing an average of 5.4 DC .
•The patient's spectacle prescription may The patient's spectacle prescription may
fluctuate for some months following surgery. fluctuate for some months following surgery.
Refractive changes and keratometry or corneal Refractive changes and keratometry or corneal
topography can be used to follow the healing topography can be used to follow the healing
processprocess .

Complications of keratoplastyComplications of keratoplasty
Surgery of keratoplasty involves Surgery of keratoplasty involves risksrisks that include:- that include:-
1.1.High post-operative regular and/or irregular High post-operative regular and/or irregular
astigmatism. myopia and astigmatism may astigmatism. myopia and astigmatism may
reduce vision directly or from aniseikonia.reduce vision directly or from aniseikonia.
2.2.Graft rejection.Graft rejection.
3.3.Infection inside the eye (endophthalmitis(. Infection inside the eye (endophthalmitis(.
4.4.Glaucoma.Glaucoma.
5.5.Steep or flat grafts.Steep or flat grafts.
6.Recurrence of KC in the new graft.

Lamellar KeratoplastyLamellar Keratoplasty
Lecture 11Lecture 11
1.1. Recently a major step forward in cornea Recently a major step forward in cornea
transplantation for keratoconus has transplantation for keratoconus has
occurred. This is the advent occurred. This is the advent مودُسقُس ; ءيءجِف مَكْمودُسقُس ; ءيءجِف مَكْ of a of a
form of partial corneal transplantation called form of partial corneal transplantation called
deep anterior lamellar keratoplasty. deep anterior lamellar keratoplasty.
2.2. In this technique a circular disc of diseased In this technique a circular disc of diseased
tissue from the centre of the patient’s own tissue from the centre of the patient’s own
cornea is cornea is removedremoved, but the innermost layer , but the innermost layer
(endothelium ) of the patient’s cornea is left (endothelium ) of the patient’s cornea is left
behind. behind.
3.3. The transplanted donor cornea has its own The transplanted donor cornea has its own
endothelium removed before it is sutured in endothelium removed before it is sutured in
place.place.

Lamellar KeratoplastyLamellar Keratoplasty
•This technique is appropriate in keratoconus This technique is appropriate in keratoconus
because in this disease the stroma is abnormal because in this disease the stroma is abnormal
whilst the endothelium is healthy. whilst the endothelium is healthy.
•Preserving the patient’s healthy endothelium has Preserving the patient’s healthy endothelium has
major advantages because in this form of major advantages because in this form of
cornea transplantation cornea transplantation rejection of the transplant rejection of the transplant
almost never occurs.almost never occurs.
• Always perform partial or deep anterior lamellar Always perform partial or deep anterior lamellar
keratoplasty in keratoconus when it is possible keratoplasty in keratoconus when it is possible
to do so. to do so.
•However if the keratoconus is too advanced, for However if the keratoconus is too advanced, for
example the cornea is example the cornea is severely scarred, this severely scarred, this
surgery may not be possiblesurgery may not be possible and penetrating and penetrating
keratoplasty will be done insteadkeratoplasty will be done instead .

Lamellar KeratoplastyLamellar Keratoplasty
Diseased corneas may be scarred and/or abnormally Diseased corneas may be scarred and/or abnormally
shaped.shaped.

Air is injected into the cornea to separate the Air is injected into the cornea to separate the
abnormal front region from endothelialabnormal front region from endothelial back regionback region

The surgeon will remove the diseased stromal region The surgeon will remove the diseased stromal region
retaining the endotheliumretaining the endothelium
the diseased stromal regionthe diseased stromal region
Is removedIs removed

TheThe abnormal stroma is then completely removedabnormal stroma is then completely removed

A healthy donated cornea is transplanted into the A healthy donated cornea is transplanted into the
patient’s cornea to replace the diseased front region. patient’s cornea to replace the diseased front region.
The corneal transplant consists only of the front region The corneal transplant consists only of the front region
of healthy cornea – the endothelial back region has of healthy cornea – the endothelial back region has
been removed- so that the new cornea fits exactly into been removed- so that the new cornea fits exactly into
the patient’s endotheliumthe patient’s endothelium .
Unremoved
endothelium

The cornea transplant is secured with ultra-fine The cornea transplant is secured with ultra-fine
suturessutures 11/0
ultra-fine sutureultra-fine suture

LASIK in KeratoconusLASIK in Keratoconus
•Keratoconus is generally considered to be Keratoconus is generally considered to be
a contraindication for Lasik, PRK, LASEK, a contraindication for Lasik, PRK, LASEK,
or any other refractive surgery technique or any other refractive surgery technique
that removes tissue. that removes tissue.
•There is a possibility that these There is a possibility that these
procedures could further weaken a cornea procedures could further weaken a cornea
that is affected by keratoconus resulting in that is affected by keratoconus resulting in
a further unstable cornea , liable to future a further unstable cornea , liable to future
perforation.perforation.

•Epikeratoplasty is effective
in patients intolerant to
contact lenses without
significant central corneal
scarring. In this procedure a
preshaped button of donor
stromal tissue called a
lenticule is placed on the
deepithelialized anterior
surface of the recipient
cornea.

Epikeratoplasty
(Epikeratophakia(

Epikertophakia
The unoperated eye The operated eye

Prevalenceةدايس of Refractive
Errors
Factors that affect the prevalence of refractive
errors :-
About refractive error distribution for example
Daniel Etyale of the W.H.O. reported at a
special session on refractive error at an
International Agency for Prevention of
Blindness meeting in 2001, that 5 -15 percent
of children are considered to have refractive
errors, the majority of which are uncorrected
(neglected).
I-Gender : Some studies found higher prevalence
of myopia among females than among males.

Prevalence of Refractive Errors
II-Race :
1.Prevalence of myopia is higher among
Americans of European ancestryةلسلسلسلة
بسنلا than among African Americans .
2.Very high prevalence of myopia have
been, reported among Asians.

Prevalence of Refractive Errors
III-Occupation :
1.Myopia is more common in persons who have
occupations involving near work.
2.Hyperopia has often been found to be
associated with poor reading ability.

Screening of Refractive Errors
IV-Family history :
Myopia is more common among persons with
a family history of myopia. Familial
resemblance is probably due in part to
inheritance and in part to common life style
factors.

Screening of Refractive Errors
•Recent studies about refractive error
distribution :Data from 29,281 people in
the US, western Europe and Australia
below 12 years of age showed a
prevalence for hyperopia (plus 3D or
greater) of 9.9 percent, 11.6 percent, and
5.8 percent, respectively, and for myopia
(minus 1D or more) 25.4 percent, 26.6
percent, and 16.4 percent for these
population samples.

Correction of
refractive errors

General guidelines for treatment of General guidelines for treatment of
hypermetropiahypermetropia
Optical correction
Spectacles :
–In young children below the age of 6 or 7, some
degree of hypermetropia is physiological, and
a correction needs to be given only if the error
is high or if strabismus is present .
–In those between 6 and 16 years, especially
when they are working strenuously at school,
smaller errors may require correction .
–If a suspicion of eye strain is suggested by more
indefinite signs, a complaint of headache or
unaccountable lassitude قاهارْهاإِر ; داهاجْهاإِر in all
these cases the refraction should be conducted
under a cycloplegic eye drops.

Correction of refractive errors
Hyperopia
Unless there is esodeviation or evidence of
reduced vision , it is not necessary to correct
hyperopia .
•When hyperopia and esotropia coexist , initial
management includes full correction of the
refractive error after cycloplegia .
• When there is spasm of the accommodation
we correct the whole of the error .
•In a school – age child , the full refractive
correction may cause blurring of distance
vision because of the inability to relax
accommodation fully ,thus we deduce about
one diopter of the objective full cycloplegic
refraction for better distant vision.

Hypermetropia " HM "
Generally , the more fully the error is corrected ,
the better the result , always provided that
the lenses are compatible with good vision .
As a compromise in a difficult case like high
HM , it may be well to under correct
considerably at first ,and to strengthen the
lenses at intervals gradually of a few months
until the full correction is comfortably borne ,
Or it may help to advise weaker lenses to
correct for distance and the full correction
for close work .

Hypermetropia " HM "
Finally the symptoms of accommodative
asthenopia may indicate a general
constitutional state as a part of general
body strain .
Its Rx is to be adequate , should not be confined
to the correction of the optical apparatus
alone , but should include an inquiry into the
general physical and nervous state , and if
necessary , should involve a reorganization
of the habits and activities of the individual
so that he lives within the limits of his
capabilities .

Predisposing factors for asthenopia
Thus typical symptoms of asthenopia come on in:-
1. The child starting school .
2. In the young studying for an examination .
3.In the girl leaving the comparative ease of
home life and setting out in business .
4. In the adult in periods of over work and
anxiety ,
5. And in them all in states of physical debility
( systemic diseases) and mental depression .

Surgery for high HM
a- Thermokeratoplasty , in which corneal
curvature is by appropriately sited
burns , produces such variable effects
as to vitiate دسفيits widespread
acceptability at present
b- The use of Excimer laser and holmium
lasers surgery Laser in-situ
keratomileusis (LASIK( is now well
known to correct up to 5 D of HM.

Treatment of myopia
General guidelines for TreatmentGeneral guidelines for Treatment::
The goals for managementThe goals for management of the patient with myopia are: of the patient with myopia are:
1.1. Clear, comfortable, efficient binocular vision Clear, comfortable, efficient binocular vision
2.2.Good ocularGood ocular healthhealth..
• The primary symptom in patients with low and The primary symptom in patients with low and
moderate myopia is moderate myopia is lack of clear vision at distancelack of clear vision at distance, ,
which can be restored by optical correction. which can be restored by optical correction.
•Treatment directed to slow the progression of myopia Treatment directed to slow the progression of myopia
is referred to as "myopia control". Effective myopia is referred to as "myopia control". Effective myopia
control results in less severe myopia and less vitreous control results in less severe myopia and less vitreous
chamber elongation than would otherwise have chamber elongation than would otherwise have
occurred.occurred.

Treatment of myopia
•Regimens to reduce myopia lessen dependence Regimens to reduce myopia lessen dependence
on spectacles or contact lenses, but they do not on spectacles or contact lenses, but they do not
lessen the risk for myopic sequelae. lessen the risk for myopic sequelae.
•ChildrenChildren should be fully corrected and, if under should be fully corrected and, if under
8 years of age, instructed to wear their glasses 8 years of age, instructed to wear their glasses
constantlyconstantly both to avoid developing the habit of both to avoid developing the habit of
squinting (Slinting)squinting (Slinting) and to enhance developing a and to enhance developing a
normal accommodation-convergence normal accommodation-convergence reflex.reflex.
• If the refractive error is low, the child may wear If the refractive error is low, the child may wear
the glasses the glasses intermittently intermittently as needed, e.g., at as needed, e.g., at
schoolschool .

Treatment of myopia
•Undercorrection of myopia Undercorrection of myopia in early childhood in early childhood
may result in an adult who has never developed may result in an adult who has never developed
a normal amount of accommodation for near a normal amount of accommodation for near
focus. This person will be uncomfortable in full focus. This person will be uncomfortable in full
correction and complain that the glasses are too correction and complain that the glasses are too
strong and "pull" his or her eyes.strong and "pull" his or her eyes.
•Cycloplegic refractionsCycloplegic refractions are mandatory. All are mandatory. All
strabismic children need cycloplegia, especially strabismic children need cycloplegia, especially
esotropic children and very high myopes (> 10 esotropic children and very high myopes (> 10
D), atropine refraction may be necessary.D), atropine refraction may be necessary.

Treatment of myopia
•In generalIn general, the refractive error, including , the refractive error, including
cylinder, should be fully corrected. Young cylinder, should be fully corrected. Young
children tolerate cylinder well. children tolerate cylinder well.
•Intentional undercorrection of a myopic Intentional undercorrection of a myopic
esotropeesotrope to decrease the angle of to decrease the angle of
deviation is rarely tolerated. deviation is rarely tolerated.
•Intentional overcorrectionIntentional overcorrection of a myopic of a myopic
refractive error may be of some value in refractive error may be of some value in
controlling an intermittent exodeviation.controlling an intermittent exodeviation.

Treatment of myopia
•ParentsParents should be educated about the natural should be educated about the natural
progression of myopia and the need for frequent progression of myopia and the need for frequent
refractions and possible prescription changes.refractions and possible prescription changes.
•Contact lensesContact lenses may be a desirable option in may be a desirable option in
older children to avoid the problem of image older children to avoid the problem of image
minification found with high- minus lenses. minification found with high- minus lenses.
•AutorefractometerAutorefractometer may be used to refract may be used to refract
myopic patients, but prescribing directly from the myopic patients, but prescribing directly from the
findings can be hazardous.findings can be hazardous.

Available Treatment Options for Available Treatment Options for
myopiamyopia Lecture 12
Optical correctionOptical correction :in the form of spectacles or contact :in the form of spectacles or contact
lenses provides clear distance vision. Whether lenses provides clear distance vision. Whether
spectacles or contact lenses are preferable in a spectacles or contact lenses are preferable in a
given case depends upon numerous factors, given case depends upon numerous factors,
including:including:
1.1. patient's agepatient's age, ,
2.2. motivation motivation زفح ، قيوشتزفح ، قيوشت for wearing contact lenses,for wearing contact lenses,
3.3. compliance compliance داياقِيانْقِاِيا ; عاياصِيا نْقِاِياداياقِيانْقِاِيا ; عاياصِيا نْقِاِيا with contact lens care with contact lens care
procedures,procedures,
4.4. corneal physiologycorneal physiology, ,
5.5.and and financial financial considerations.considerations.

Treatment of myopia
•Spectacle:Spectacle: (Spherical (Spherical concaveconcave lenses lenses))

•
FOCUS FOCUS

Treatment of myopia
11) Below 6 D (I.e. for low and moderate myopia). ) Below 6 D (I.e. for low and moderate myopia).
Full correction must be ordered. Children should Full correction must be ordered. Children should
wear their distant vision glasses wear their distant vision glasses constantlyconstantly for for
two reasons:two reasons:
aa) Visual development: If the glasses are not worn, ) Visual development: If the glasses are not worn,
the image is not formed on the retina. It is no the image is not formed on the retina. It is no
longer stimulated and the eye becomes 'lazy' longer stimulated and the eye becomes 'lazy'
(amblyopic).(amblyopic).
b(b( Mental development - without glasses myopes Mental development - without glasses myopes
do not take interest in school since they cannot do not take interest in school since they cannot
see the blackboard, also they can not form a see the blackboard, also they can not form a
good idea about the nature or the real shape good idea about the nature or the real shape
and size of objects.and size of objects.

Treatment of myopia
2(2( Above 6 D (high myopia) - slight under Above 6 D (high myopia) - slight under
correction, because strong minus lenses correction, because strong minus lenses
considerably diminish the size (minify) of considerably diminish the size (minify) of
the retinal images and make them very the retinal images and make them very
bright and clear. The very bright and clear bright and clear. The very bright and clear
images are uncomfortable to the myope images are uncomfortable to the myope
because the retina has been accustomed because the retina has been accustomed
to large and indistinct images.to large and indistinct images.

Treatment of myopia
Contact lenses are indicated Contact lenses are indicated
particularly in high myopia.particularly in high myopia.
•

Advantages and disadvantages of
contact lenses
Advantages:
1.Contact lenses may have optical advantages for some patients in
addition to the cosmetic benefit and the convenience ةمءملم of
not having to wear glasses.
2.In high degrees of ametropia, peripheral distortions are reduced
with contact lenses due to their small diameter and thinness.
3.Even binocular aphakics enjoy the better peripheral vision,
minimum distortion, and reduced magnification that they get
with contact lenses.
4.A patient with keratoconus or an irregular cornea for some other
reason can frequently achieve satisfactory vision with contact
lenses when little or no improvement can be obtained with
spectacle.
5.The advantages for those engaged in athletics or with special
occupational needs are obvious.

Disadvantages:
1.Contact lenses are expensive and easily lost or destroyed.
2.Rigid lenses are initially uncomfortable and require a period
of adaptation.
3. With the exception of extended-wear lenses, which are
replaced at prescribed intervals, the care and cleaning of
daily-wear contact lenses are important and must be done on
a daily basis.
4.Wearing time may be limited by physiologic factors, and the
patient may still have to wear glasses part of the time.
5.A superficial ocular infection becomes more significant in
the contact lens patient.
6.Corneal ulcers may occur with contact lenses; they never
occur as a result of wearing spectacles.
7.Foreign bodies may become entrapped under a contact lens
instead of being immediately washed out by tears.

Treatment of myopia
•Advantages of contact lens over spectacles :Advantages of contact lens over spectacles :
1(1( Provide normal field of vision. Provide normal field of vision.
2(2( Aberrations associated with spectacles – Aberrations associated with spectacles –
prismatic distortion, spherical and chromatic prismatic distortion, spherical and chromatic
aberration are eliminated.aberration are eliminated.
3(3( Cosmetically contact lenses are more pleasant Cosmetically contact lenses are more pleasant
than thick myopic glasses. However contrary to than thick myopic glasses. However contrary to
popular belief contact lenses have not been popular belief contact lenses have not been
proved to reduce the degree of myopia. proved to reduce the degree of myopia.

Treatment of myopia
OrthokeratologyOrthokeratology
•Orthokeratology is the programmed fitting of a Orthokeratology is the programmed fitting of a
series of contact lenses, over a period of weeks series of contact lenses, over a period of weeks
or months, to flatten the cornea and reduce or months, to flatten the cornea and reduce
myopia. Studies of orthokeratology with standard myopia. Studies of orthokeratology with standard
rigid contact lenses show that individual’s rigid contact lenses show that individual’s
response varies considerably to orthokeratology, response varies considerably to orthokeratology,
with myopia reduction up to 3.00 D obtained in with myopia reduction up to 3.00 D obtained in
some patients. some patients.
•The average reduction reported in studies was The average reduction reported in studies was
0.75-1.00 D; most of this reduction occurs within 0.75-1.00 D; most of this reduction occurs within
the first 4-6 months of the orthokeratology the first 4-6 months of the orthokeratology
program. program.

Treatment of myopia
•Corneas with greater peripheral flattening Corneas with greater peripheral flattening
are thought more likely to have successful are thought more likely to have successful
central flattening, thus leading to reduced central flattening, thus leading to reduced
myopia via orthokeratology.myopia via orthokeratology.
•With adequate follow up care, With adequate follow up care,
orthokeratology is a safe and effective orthokeratology is a safe and effective
procedure. However, studies suggest that procedure. However, studies suggest that
refractive error shifts toward the original refractive error shifts toward the original
baseline( starting linebaseline( starting line ) in patients.n patients.

Treatment of myopia
Visual hygiene Visual hygiene recommendationsrecommendations include include
the following:the following:
1.1.When reading or doing intensive near When reading or doing intensive near
work, take a break about every 30 work, take a break about every 30
minutes. During the break, stand up and minutes. During the break, stand up and
look out a window.look out a window.
2.2.When reading, maintain proper distance When reading, maintain proper distance
from the book .The book should be at from the book .The book should be at
least as far from the eyes as 40 cm.least as far from the eyes as 40 cm.

Treatment of myopia
3.3.Be sure that illumination is sufficient for Be sure that illumination is sufficient for
reading. Avoid glare on the page by using a reading. Avoid glare on the page by using a
diffuse light source and allowing it to shine on diffuse light source and allowing it to shine on
the page from behind (over the shoulder) the page from behind (over the shoulder)
,rather than shining or reflecting toward the ,rather than shining or reflecting toward the
eyes.eyes.
4.4.Read or do other visual work using a relaxed Read or do other visual work using a relaxed
upright posture.upright posture.
5.5.Place a limit on the time spent watching Place a limit on the time spent watching
television and watching video games. Sit 5-6 television and watching video games. Sit 5-6
feet away from the television.feet away from the television.

Treatment of myopia
•LasikLasik (laser Assisted in situ (laser Assisted in situ
keratomileusiskeratomileusis): In LASIK a thin, central flap is ): In LASIK a thin, central flap is
created in the outer layers of the cornea, created in the outer layers of the cornea,
consisting of the epithelium and a portion of the consisting of the epithelium and a portion of the
outer stroma. Following lifting of the flap, the outer stroma. Following lifting of the flap, the
laser is used to reshape the exposed stromal laser is used to reshape the exposed stromal
bed. The flap is replaced without the need for bed. The flap is replaced without the need for
sutures, and the edges heal over night.sutures, and the edges heal over night.
• The entire process takes just minutes to The entire process takes just minutes to
perform. As the flap of the epithelium remains perform. As the flap of the epithelium remains
intact immediately following the procedure, intact immediately following the procedure,
vision recovers quickly and discomfort is kept to vision recovers quickly and discomfort is kept to
a minimum. a minimum.

General guidelines for final General guidelines for final
correction of astigmatismcorrection of astigmatism
1.1.In children requiring correction, the full In children requiring correction, the full
astigmatic correction is given.astigmatic correction is given.
2.2. If the child is amblyopic from unilateral If the child is amblyopic from unilateral
astigmatism; a trial of lenses is indicated before astigmatism; a trial of lenses is indicated before
occlusion therapy. occlusion therapy.
3.3. In adult who is asymptomatic, be waryIn adult who is asymptomatic, be wary. ر ذِياح . ر ذِياح
س رِياتَرِحْقِ مُس رِياتَرِحْقِ مُ of changing the axis of their correcting of changing the axis of their correcting
cylinder even if apparently incorrect, they have cylinder even if apparently incorrect, they have
achieved adaptation to distortion and blur and achieved adaptation to distortion and blur and
will often be unhappy with any change.will often be unhappy with any change.

General guidelines for final General guidelines for final
correction of astigmatismcorrection of astigmatism
4.4.If an adult was previously fully corrected and If an adult was previously fully corrected and
the amount of astigmatism has changed, he the amount of astigmatism has changed, he
will probably tolerate full correction, especially will probably tolerate full correction, especially
if the axis at 90 or 180.if the axis at 90 or 180.
5.5. If an adult was not corrected for the full If an adult was not corrected for the full
amount of astigmatism, distortion may result in amount of astigmatism, distortion may result in
a real problem. The only way to predict this is a real problem. The only way to predict this is
with full correction with full correction in placein place in the trial frame in the trial frame
under binocular condition and ask the patient under binocular condition and ask the patient
about any distortion.about any distortion.

General guidelines for final General guidelines for final
correction of astigmatismcorrection of astigmatism
6.6.If the patient is intolerant of the cylinder If the patient is intolerant of the cylinder
correction, correction, contact lensescontact lenses will reduce the will reduce the
distortion associated with the correction distortion associated with the correction
of the astigmatism. of the astigmatism.
7.If the patient is equally intolerant of the 7.If the patient is equally intolerant of the
distortion or incapable or intolerant of distortion or incapable or intolerant of
contacts, consideration of refractive contacts, consideration of refractive
surgery (LASIK) should be given.surgery (LASIK) should be given.

Treatment of Astigmatism
Spectacle Lenses have an inverse proportion of correction
with the degree of astigmatism.
•According to the type of astigmatism the corrective
lens will be determined:-
1.Regular astigmatism :in which the two principle
meridians are at right angle and is susceptible to
easy correction by cylindrical lenses.
2.Oblique astigmatism :in which the two principle
meridians are not at right angle but are crossed
obliquely , it is corrected by using
spherocylindrical lenses ,it is not very common.
3.Irregular astigmatism :where there are
irregularities in the curvature of the meridians so
that no geometrical figure is formed ,and the
correction is very difficult.

Treatment of Regular
Astigmatism
Uncorrected astigmatism
Corrected astigmatism

Because the light is split into two separate foci in
astigmatic eye, a lens with two different power curves is
needed to correct the astigmatism. These lenses are
called cylindrical Lenses.
Because of the different powers, these lenses have a
variable edge profile that is thinner in some places and
thicker in others. These lenses are more complex and have
to be of the highest optical quality in order to produce
good vision for the astigmatic patient..
Spectacles

Treatment of Irregular
Astigmatism
The optical treatment of all these varieties of
irregular astigmatism is often unsatisfactory.
•The refraction must be estimated by a time-
consuming method of trial and error, which
is frequently unrewarding (unsatisfactory(.
•Improvement with spectacle lenses will in
many cases be disappointingly small, but
determined attempts to improve the vision by
this means should be made as the results
may occasionally be surprisingly
satisfactory.

Treatment of Irregular
Astigmatism
•Typically in conical cornea but even in other
cases with actual opacities present, an
immenseلئاه visual improvement may be
obtained by employing hard or semi-soft
contact lenses.
•In other cases where the condition is serious
lamellar keratoplasty in central area of a conical
cornea or excision of a scar and its replacement
by a graft (Epikeratoplasty( is the most
effective method of treatment.

Surgeries available for astigmatism
1.AK( (Astigmatic
keratotomy
2.PRK
3.LASIK
4.Lens surgery
5.LASEK
6.Intacs

Lecture 13

Corneal surgery
1. Arcuate keratotomy involves making paired arcuate
incisions on opposite sides of the cornea in the axis
of the correcting "plus" cylinder (the steep
meridian(. The resultant flattening of the steep
meridian coupled with a smaller steepening of the
flat meridian at 90 degree to the incisions reduces
astigmatism.
•The desired result can be controlled by varying the
length, depth of the incisions and their distance from
the optical centre of the cornea.
•Arcuate keratotomy may be combined with
compression sutures placed in the perpendicular
meridian, when treating large degrees of
astigmatism such as may occur following
penetrating keratoplasty.

Surgeries available for astigmatism
•2. PRK can correct up to 3D.
•Since the advent of LASIK the procedure
is being performed less frequently and is
largely reserved for patients who are
unsuitable for LASIK .
•3. LASIK can correct up to 15D.

Surgeries available for astigmatism
4-Lens surgery :
•Involves using a toric intraocular implant at the
time of cataract extraction. However,
postoperative rotation of the implant away from
the desired axis may occur.
•Lens surgery involves:
A-Removal of the crystalline lens without I.O A-Removal of the crystalline lens without I.O
Lens implantation.Lens implantation.
B- Nonremoval of the crystalline lens with I.O B- Nonremoval of the crystalline lens with I.O
Lens implantationLens implantation

Non corneal interventionNon corneal intervention
A( Removal of lens was attempted occasionally A( Removal of lens was attempted occasionally
in the past to neutralize high myopia.in the past to neutralize high myopia.
The operation is hazardous since it may cause :The operation is hazardous since it may cause :
1.1.Vitreous lossVitreous loss
2.2.Retinal detachment.Retinal detachment.
3.3.Loss of accommodationLoss of accommodation
4.4.Near work should be restricted.Near work should be restricted.
5.5.Illumination must be good, print should be large.Illumination must be good, print should be large.
B( Nonremoval of the crystalline lens with I.O B( Nonremoval of the crystalline lens with I.O
Lens implantation in AC to decrease the Lens implantation in AC to decrease the
refractivity of the eye.refractivity of the eye.

Astigmatic keratotomy( AK)
•Astigmatic keratotomy is a variation of
RK (radial keratotomy(, used to treat
astigmatism.
• AK uses arc-shaped incisions in the
cornea, whereas RK uses radial
incisions, like the spokes of a wheel.
Neither RK nor AK is performed with a
laser.

Glare at night can also be expected for the
same length of time. Some patients have
complained for up to 3 years. However, glare
testing shows no significant glare after 1 year
in 99.3% of the cases. Approximately 83% of
patients in the expected range achieve unaided
post-operative 20/40 (or better) vision.

The Procedure Of AK
The patient is given a mild
sedative prior to surgery and the
eye is prepared normally.
Generally, the non-dominant eye
is selected for the first operation
, with an average minimum wait
of one week before surgery is
performed on the dominant eye.

•During the operation, the front surface of the eye is
numbed with drops (TOPICAL ANAESTHESIA).
•Some surgeons advocate retro-bulbar anesthesia.
•A mark in a spoke-like pattern is then impressed the
cornea. This is temporary and is used for marking
where the surgeon will make the incisions. The marks
are based upon a formula determining your
prescription, age, and the amount of correction
needed.
The Procedure Of AK

The Procedure Of AK
The surgeon will then make several
incisions (keratotomies) in the cornea
using a microscope and a microscopic
surgical instrument that has a diamond tip.
This diamond instrument has a safeguard
which prevents it from penetrating into
your eye. The actual surgery time takes
about 5 minutes but with pre-operative
preparations it can take up to an hour.

Precise microscopic control must be
maintained over the length, depth, and
arrangement of these micro-incisions in order
to achieve proper optical correction.
These micro-incisions allow the central
cornea to be regular, removing the
asymmetric shape that causes astigmatism,
thus partially or completely correcting the
vision impairment.
The Procedure Of AK

The Procedure Of AK
•Antibiotic and cycloplegic drops are then
applied and the lid speculum removed.
•A patch is then placed on the eye for
approximately 2 hours.
•Other than diligent ن قَرِتمُ . دهتجم care to
avoid getting the eye patch soiled or wet,
there are no restrictions placed on the
patient.
• Antibiotic drops are used for
l-2 weeks after the surgical procedure.

After Operation
1-For the first 24 hours after the surgery, the
patient may experience some sensitivity to light,
mild scratchiness, and/or redness in the
operated eye.
2-There may also be some pain which is usually
alleviated by common, pain killer medication.
3-Vision is usually good within the first week,
but fluctuation of visual acuity from morning to
night can be expected for up to 6 months or
longer. Occasionally, a second operation is
needed to reduce any residual myopia.

PRK: Photorefractive Keratectomy
PRK: Photorefractive Keratectomy uses the cool
beam of the excimer laser to reshape the front of
the eye by treating the surface of the cornea so
that light rays focus more sharply on the retina.
The outer surface of the cornea, called the
epithelium, must be removed.
This is accomplished by carefully scraping it away.
The laser is then applied to remove microscopic
amounts of corneal tissue, measured in microns.

PRK: Photorefractive Keratectomy
•The epithelium grows back over the
treated area within several days. A
"bandage" contact lens is placed on the
eye to minimize discomfort during this
healing period.
•Complete healing and visual recovery can
take as long as 3-6 months with PRK.

Excimer laser
PHOTOREFRACTIVE
KERATECTOMY
•The excimer laser makes pulses of
invisible ultraviolet light. Each pulse of
light removes a microscopic layer from the
corneal stroma, changing the curvature of
the cornea ever so slightly.

PHOTOREFRACTIVE
KERATECTOMY
•To correct nearsightedness, the curvature
of the cornea must be decreased the
cornea must be made flatter.
• To correct farsightedness, the curvature
of the central cornea must be increased.
•To correct astigmatism, the curvature
must be altered in one specific direction.

PHOTOREFRACTIVE
KERATECTOMY
•Low amounts of nearsightedness, astigmatism
or farsightedness, will require smaller amounts
of tissue removal, and larger corrections will
require greater amounts. The total treatment
usually takes less than one minute of actual
laser time

PHOTOREFRACTIVE
KERATECTOMY
•A computer running specialized software
determines the exact pattern of pulses
needed to remove the right amount of
corneal tissue. The computer also directs
the actual operation of the laser system.

PHOTOREFRACTIVE KERATECTOMY
DISADVANTAGES AND COMPLICATIONS
•1-Discomfort is very minimal during or after the
procedure.
•2-Fewer than 2% report any kind of pain.
•3-It is normal to have a sensation of dryness or
"tired eyes" after surgery. This sensation
diminishes with time.
• 4-The eyes may be red following the procedure.
This redness is harmless, and will fade within a
few days.

PHOTOREFRACTIVE KERATECTOMY
DISADVANTAGES AND COMPLICATIONS
5-Many people will experience glare or
haloes at night for a few weeks to several
months postoperatively. This diminishes,
and in most cases will disappear entirely
over time.
6-Undercorrection or overcorrection

If any of the following conditions apply to you,
then you are NOT a good candidate for PRK
Contraindications of PRK
1.KERATOCONUS.
2.High I.O.P
3.Intraocular inflammation
4.Weak cornea due to local or general
disease
5.Cataract

6.Pregnancy.
7. Unstable refractive error (your vision has
been changing over the past 12 months).
8. Collagen/Vascular disease.
9. Active ocular disease.
10. Under 18 years of age.
11. Pacemaker users.
Contraindications of PRK

كزــياللا ةــــيالمع LASIK
Laser in-situ keratomileusis
• ر زيالرميزكزلا ةعشأ طيالست ةيالمع ن ع ةر ابع يه كزياللا ةيالمع
ةيانرقلا ن م ءزج عطق متي ثياح ،ةيالخادلا ةيانرقلا تاقبط ىلع
ر ادقمب ينورتكللا عطقلا زاهج ةطاسلسلةوب270 دعبو ،ةجر د
ىلع ر زياللا ةعشأ طيالستو عوطقملا ءزجلا ينث متي كلذ
عوطقملا ءزجلا ةداعإ متي كلذ دعب ،ةيانرقلل ةيالخادلا تاقبطلا
.هطاياخ نودب يعيابطلا هناكم ىلإ ةيانرقلا ن م
LASIK combines the precision of the
excimer laser that is used in PRK
surgeries with the flap technique that
characterizes this surgery.

LASIK Surgery
Laser in-situ keratomileusis
There are FDA regulations governing which
particular excimer laser may be used to correct which
particular type and degree of refractive error. For
instance, one excimer laser was recently approved for
LASIK treatment of nearsightedness up to -14.0
diopters with or without up to -5.0 diopters of
astigmatism. These are high amounts of refractive
error and include most nearsighted people. But there
are quite a few people with more than -14.0 diopters
of nearsightedness, and the FDA feels they will not
achieve a satisfactory result.

LASIK
LASIK FACTS
•Range of Correction: LASIK, Laser
Assisted In Situ Keratomileusis, is state-
of-the-art in refractive surgery. It is used to
correct nearsightedness up to 20 diopters,
farsightedness up to 5 diopters, and
astigmatism up to 5 diopters

LASIK
•However with LASIK, the epithelium is not
removed. Instead, using a precision
instrument called a microkeratome, a
hinged flap consisting of an extremely thin
layer of epithelial tissue is created.
• This flap is then gently folded back out of
the way while precisely measured pulses
of cool laser light are applied to the
underlying tissue.

LASIK
•The non-thermal laser breaks the molecular
bonds of corneal cells, which are vaporized a
layer at a time, until the desired correction is
achieved. These changes to the cornea are so
minute that they must be measured in microns…
thousandths of a millimeter (It would take 200
pulses of the laser to cut through the thickness
of a single human hair!)

LASIK
•Afterward the flap is carefully repositioned
where, thanks to the remarkable natural
bonding qualities of the corneal tissue, it
adheres and quickly heals without the
need for stitches. Drops to prevent
infection may be used for a few days
following LASIK.

LASIK
•Where is it done? LASIK is performed as
an outpatient procedure with topical
anesthetic and a mild sedative. It takes
about fifteen minutes per eye, with both
eyes being done on the same day.

LASIK
•Age is a factor: We do not offer LASIK to
anyone under 18. Young people's eyes
are often still changing rapidly. A stable
eyeglasses prescription (no significant
changes in the past two years) is
important to a good outcome.

LASIK
•During the use of the microkeratome
some patients notice a sensation of
pressure and a "graying" of vision,
associated with a "suction ring" which
holds the eye steady.

LASIK
•Recovery with LASIK is very rapid. Most
people achieve good, functional vision and
can go back to work within 2 days.

LASIK Results
•The results are even better: 96% of the patients
achieve 20/20 or better vision without glasses,
with 99% of the patients achieving 20/25 or
better vision. After the initial treatment, 90% of
patients will have 20/25 or better vision without
glasses, and 99% will have 20/40 or better vision
without glasses. 20/40 vision is good enough to
pass the driver's vision test without glasses
For patients with mild nearsightedness,
farsightedness, or astigmatism, the results are
even better. Patients requiring higher amounts of
correction will have less accurate results.

LASIK Advantages
•1-The quality of vision after laser vision
correction is usually superior to vision with
contact lenses or glasses.
•2-Patients generally have less glare than they
had with contact lenses
•3-The inconvenience and discomfort of contact
lenses is eliminated.
•4-Side vision isn't blocked, as it is with glasses
•5- There is no longer the problem of dirty, wet or
scratched glasses.

RESULTS
•6-The vast majority of patients no longer
need glasses or contact lenses for
distance vision after laser vision correction
treatment.

PRK versus LASIK : Comparisons
range of correction
PRK LASIK
low to moderate low to severe
wound depth superficial 20% deep
intraoperative pain none none
post-operative
medications
3 months, possibly more 1-2 weeks
functional vision
recovery
3 to 5 days 24 hours
Corneal epithelium Completely removed Completely repositioned
visual results fully
recognized
3 weeks to several
months
1 to 4 weeks
return to work 3 to 5 days 1 day
risk of complications low (more surgeon
dependent(
low (less surgeon
dependent(
risk of scarring in central
cornea
1-2 % >1%

كزيللا ةيلمعل ةيريضحتلا تاوطخلا
Indications and
Contraindications Of LASIK
تاوطخ يهو ،كزياللا ةيالمعل ةيرياضحتلا تاوطخلا لودجلا ن يابي
ل امم ن ياعلل قياقدو لماكز صحفب ماياقلا يعدتستو ةلوطم
حوارتت ةليوط ةدم رياضحتلا ةيالمع قرغتست نأ هعم برغتسي
.ن مزلا ن م ن ياتعاسلسلة ىلإ ةعاسلسلة ن ياب ام
تاصوحفلا مهأ ن م دحاو ن ياعلل يفارجوبطلا ريوصتلل ةر وص
كزياللاو ر زياللا تايالمعل ةيرياضحتلا

ن ياعلا طغض س اياق1
،كزياللا ةيالمع لبق هنياع طغض ضيرملا فرعي نأ مهملا ن م
ءارجإ دعب ن ياعلا طغضل يقياقح رياغ اً ضافخنا كانه نل
ن ياعلا طغض لاقي لاً ثمف ماقر لاب ن ياعلا طغض بتكي ةيالمعلا
17 ن م ن ياعلل يعيابطلا طغضلا نأب اً ملع قبئز رتميالم 11
ىلإ19 قبئز رتميالم

ن ياعلل يفارجوبطلا ريوصتلا2
.ةيالمعلا ءارجإ لبق يسلسلةاسلسلةأ بلطتم ن ياعلل يفارجوبطلا ريوصتلا
.ةياطورخم ةيانرق هابتشا اهب دجوي يتلا ن ياعلا داعبتسلسلةل كلذو
ن ياعلل يفارجوبطلا لكشلا ن يابت ةنولم ةر وص

The Before image is
relatively steep, as
indicated by the green and
yellow colors. This patient
also had astigmatism
(irregularly shaped cornea)
seen as an hourglass
shape, in yellow.
After the procedure,
topography shows a
much flatter, and more
even cornea. This
patient had nearly 8
diopters of myopia and
astigmatism corrected.

س اياق ةينرقلا ةكامس3
Pachymetry
ضعب يف ةيلمعلا ءمارجإ نم عنمي دق ةينرقلا ةكامس ضافخنا
رظن رصق مهايدل نمل لماكلا حيحصتلا نم دحي دقو ،نايحيلا
ةينرقلا ةكامس لاقي لً يثمف ماقرلاب ةينرقلا ةكامس بتكت ديدش
520 نوركيام

يراسكنلا فارحنلا سايق4
ASTIGMATISM
ةياناكمإ ىدم ديدحت ن كمي ير اسكنلا فارحنلا س اياق ىلع ءً انب
.اهئارجإ لاح يف حاجنلا ةبسنو همدع ن م ةيالمعلا ءارجإ
ةباتكزو صقان وأ دئاز ةملاع عضو عم ماقر لاب س اقملا بتكي
فارحنلا ةيواز دوجو ةلاح يف Axis of cylinder

ىرخأ عناوم5
دنع صتخملا بيابطلا اهفشتكي دق ىرخأ عناوم ىلإ ةفاضلاب اذه
.ةيالمعلا لبق ن ياعلا ىلع فشكلا
ن مزملا يسلسلةوريافلا ةيانرقلا باهتلا لثم

نيعلا نم يماملا ءمزجلا صحف6
ةفرعم ن م حارجلا ن كمي ن ياعلا ن م يماملا ءزجلا صحف
جتان ةيالمعلا ءارجإ ن م عنمت دقو ن ياعلا اهياناعت ىرخأ ضارمأ
ن فجلاو ةمحتلملاو ةسلسلةدعلاو ةيانرقلا عضو ن ع تاناياب صحفلا
ن ياعلا ن م يماملا ءزجلا ةياقبو
As iridocyclitis and corneal scarring and
keratoconjuctival sicca

نيعلا عاق صحف7
اهجلاع مزلي هنإف ةياكبشلا يف بوقث وا ضارما دوجو ةلاح يف
يصاصتخا ةعجارمب حصني امكز كزياللا ةيالمع يف ءدبلا لبق
يلاعلا رظنلا رصقب ن ياباصملا لكل اً ير ود ةياكبش
يرصبلا بصعلا ةلاحو ةياكبشلا لكشل مسلسلةر صحفلا جتان
ِياAs complications of high myopia

برق نع راصبلا8
Presbyopia
،ن ياعبر لا ن سلسلة ن م نوبرتقي ن يذلا صاخشلل مهم صحفلا اذه
ءارجإ دعب ةءارق ةر اظن ىلإ مهجاياتحل لً امتحا كانه نإ ثياح
كزياللا

ناوللا ةيؤر سايق9
Colour vision
اورجأ ن يذلا ةمدخلل ن يامدقتملا لبقت ةيركسعلا تايالكلا ضعب
انه ن مو ناوللل ةياعيابط ةيؤر طرتشت اهنكلو ،كزياللا ةيالمع
جتان صاخشلا ن م عونلا اذهل صحفلا اذه ةيامهأ تءاج
ناوللل ةياعيابط ةيؤر :يلاتلا وحنلا ىلع ةداع بتكي صحفلا
ناوللل ةياعيابط رياغ ةيؤر وأ

يركسلاو لمحلا صحف10
بارطضا ،عضولا ن ياح ىلإ ةيالمعلا لجؤي دق لاُثم لمحلا دوجو
اذكهو ةيالمعلا ءارجإ ن م عنمي دق ركسلا ضيرم يدل يركسلا
ىرخأ ةيانطاب ضارمأ دوجو ةفرعم

ماعلا ىحصلا عضولا11
لبق هبيابطو ضيرملا ن ياب ر واشتلاو صحفلا ن م مهم ءزج اذه
،اهيالإ لوصولا ن كمي يتلا ةياعقاولا جئاتنلا ةفرعمو ةيالمعلا
اهيالإ لوصولا ن كمي ل ةيالاثم تاعقوت لياخت ضيرملا بنجي
تافعاضملا بسنو حاجنلا بسن ةفرعم ةيالمعلا للاخ ن م
تاميالعتلاو ةيالمعلا بقع ةيؤرلا ر ارقتسلسلةل عقوتملا تقولاو
اهدعبو ةيالمعلا لبق اهعابتا بولطملا

ةينرقلا بدحت سايق12
Keratometry
تافعاضم ثودح لامتحا ن م ديزي دق ةيانرقلا بدحت عافتر ا
دوجو اً جتان نوكي دق ريابكلا عافتر لا نأ امكز ،ةيالمعلا للاخ
ةداعلا يف يتلاو ةيانرقلا بدحت ةجر د ديدحت ةياطورخم ةيانرق
ن ياب ام نوكت42-44 ةجر د

ؤبؤبلا رطق سايق13
بقع ةيالياللا ةيؤرلا ىوتسم ىلع رثؤي دق ن ياعلا ؤبؤب رطق عافتر ا
ن ياب نوكي ام ةداع ن ياعلا ؤبؤب رطق ةفرعم كزياللا ةيالمع5-7
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