Refractive errors

EYE DISORDERS ; REFRACTIVE ERRORS

1. REFRACTIVE
ERRORS
SUDESHNA BANERJEE DUTTA
SENIOR LECTURER
S.R.S.V.MB.SC NURSING COLLEGE

2. INTRODUCTION
✓Refractive errors means that the shape of eye doesn’t
bend light correctly resulting in a blurred image .
✓The main types of refractive errors are
1. Myopia ( near sightedness )
2. Hyperopia(hypermetropia) ( far sightedness ) ( long
sightedness )
3. Presbyopia( loss of near vision with age )
4. Astigmatisms ( both) ( near sightedness ) ( long
sightedness )

3. ❑Emetropia(optically normal eye) can be defined as a
state of refraction, when the parallel rays of light coming
from infinity are focused at the sensitive layer of retina
with the accommodation being at rest
❑Ametropia(a condition of refractive error) is defined as
a state of refraction, when the parallel rays of light coming
from infinity, (with accommodation at rest), are focused
either in front or behind the sensitive layer of retina

4. REFRACTIVE
ERRORS
✓Myopia or short-sightedness is a type of
refractive error in which parallel rays of light coming from
infinity are focused in front of the retina when
accommodation is at rest

5. ETIOLOGY
Axial myopia results from increase in the antero-
posterior length of the eyeball
Curvaturalmyopia occurs due to increased curvature of
the cornea, lens or both.
Index myopia results from increase in the refractive
index of the crystalline lens associated with nuclear
sclerosis.

6. ETIOLOGY
Infection adenovirus
Injury due to optic nerve damage
Ultraviolet radiation
eye disease
Inherited
Aging ( above 45year )
Environmental factors
Previous corneal injury
Previous eye surgery
Optic nerve hypoplasia

7. TYPES OF MYOPIA
Congenital Myopia is present since birth. Usually the error is of
about -8 to -10 diopters, which mostly remains constant. It may be
associated with other ocular congenital anomalies
Simple Myopia It is the commonest variety, which results from
biological variation in the development of eye. simple myopia starts
at school age and very slowly progresses till adult age. Usually the
error does not exceed -6 to -8 diopters
Pathological Myopia or Degenerative Myopia is a rapidly
progressive error resulting in high myopia. (more than -8 D) during
early adult life, which is usually associated with degenerative
changes in the retina Genetic factors play major role in the etiology
of pathological myopia.

8. HYPEROPIA
Far-sightedness also known as long sightedness
Hyperopiais a condition of the eye in which light is
focused behind the retina , instead of on the retina.
Resulting in an inability to seen near objects clear .
Causes: Abnormal shape of cornea

10. ETIOLOGY OF
HYPEROPIA
Axial hypermetropiais by far the commonest form. It
occurs due to short axial length of the eyeball
Curvaturalhypermetropiaoccurs due to comparatively
flatter curvature of the cornea or lens or both
Index hypermetropiaresults due to change in the
refractive index of the lens
Positionalhypermetropiaresults due to posteriorly
placement of crystalline lens

11. ETIOLOGY OF
HYPEROPIA
Absence of the lens (aphakia) either congenital or
acquired (following surgical removal of the lens) leads
to high hypermetropia.

12. CLINICAL
FEATURES
Tiredness of Eyes
Frontal Or Fronto-temporal Headache
Watering
Mild Photophobia
Asthenopia(Straining of eyes)

13. MANAGEMENT
Appropriate convex lenses in the form of spectacles or
contact lenses
SURGICAL MANAGEMENT
Refractive corneal surgery

14. PRESBYOPIA
Presbyopiais a common type of vision
disorder that occurs as you age. It is often
referred to as the aging eye condition . Result in
the inability to focus up close , a problem
associated with refraction in the eye

16. ETIOLOGY OF
PRESBYOPIA
Decrease in the accommodative power of crystalline
lens with increasing age, leading to presbyopiaoccur
due to:
Decrease in the elasticity and plasticity of the
crystalline lens
Age related decrease in the power of ciliarymuscle.

17. CLINICAL
FEATURES
Typically patient complains of slowly
progressive difficulty in focusing the near objects,
while distant vision is not affected.

18. MANAGEMENT
Convex glasses of an appropriate power

19. ASTIGMATIS
M
It is a condition in which an abnormal
curvature of the corneaoccurs .
Astigmatisms may cause eye strain and may
be combined with nearsightedness or long-
sightedness .

21. ETIOLOGY OF
ASTIGMATISM
Usually occurs due to unequal curvature of cornea
Rarely it may occur due to subluxationabnormalities
of the curvature of the lens.

22. MANAGEMENT
Cylindrical lenses in the form of
spectacles or contact lenses
SURGICAL MANAGEMENT
Keratoplasty

23. PATHOPHYSIOLOG
Y
Due to etiology factors such as infection
Degenerative changes causes by gradual loss of
elasticity of lens
Decreased ability to accommodate
Refractive errors

24. DIAGNOSTIC EVALUATION
HISTORY TAKING
CORNEAL TOPOGRAPHY : This computerized test
maps the curve of your eye cornea , it can show problem
with eye surface like swelling or scarring
SLIT LAMP EXAM: The doctor uses this microscope to
shine a beam of light shaped like a small slit on effected
eye .he may dilated pupils during the test it help
diagnose .

25. CORNEAL TOPOGRAPHY

26. SLIT LAMP EXAM

27. DIAGNOSTIC EVALUATION
TONOMETRY:Test measures the pressure inside eye
.which is called intra ocular pressure
RETINOSCOPY: Is a technique obtain an objective
measurement of the refractive error of a patients eye

29. PHARMACOLOGICAL
MANAGEMENT
Cycloplegicdrugs are used to refraction ( to paralyze
the ciliarymuscle in order to determine the true
refractive error of eye )
Cholinergics(Miotics): Pilocarpine, Carbachol-It
increases aqueous fluid outflow by contracting the
ciliarymuscles
Beta blockers : Betaxolol, Timolol
Decreases aqueous humor production

30. SURGICAL MANAGEMENT
Keratomileusis: Is a method of reshaping the cornea surface to
change its optical power.
LASIK-laser eye surgery : ( laser assisted in situ kereto-
mileusis)
✓This procedure used to treat nearsightedness ,farsightedness
✓A laser is used to reshape the cornea –the clear ,round dome at
the front of the eye
✓To improve the way the eye focuses light rays onto the retina at the
back of the eye.

31. SURGICAL MANAGEMENT
AUTOMATIC LAME -LLAR KERATOPLASTY (ALK)
✓Keratoplastyis the procedure where by abnormal
corneal tissue is replaced by a healthy donor cornea
✓Is a older type of vision surgery carried out by making a
flap in the cornea to help correct severe short
sightedness and long sightedness.

32. SURGICAL MANAGEMENT
LASEK LASSER ASSISTED SUB EPITHELIAL
KERATOMILEUSIS : The hinged flap made in laser
assisted epithelial kerato-mileusissurgery is created in
the epithelial layer of eye . Inserted of creating a thicker
corneal flap as in laser assisted epithelial kereto-
mileusissurgery
PHOTO REFRACTIVE KERETOTOMY (PRK) : To correct
myopia The eye surgeon then gently remove the surface
of corneal cells ( epithelium )

33. NURSING MANAGEMENT
Safe administration of the prescribed fluid
Right documentation
Monitor the hemodynamic pressure, vital sign, arterial
blood gas
Assess the patient for any previous allergy to medicine,
fruits etc
When we administer any new medicine we have to
observe the side effect of it
We must have the knowledge about the sign symptoms of
shock
Observe the response to the treatment