Strabismus (1).ppt

Ftyh

1. DONE BY:
KamalSub-Laban
MahmoudSalman
Mustafa Jaber

2. Anatomy Review
•The eye layers:
1-A tough outer coat (fibrous).
2-A rich vascular coat (the choroid)
3-innermost neural (retnia).

3. Medial and lateral recti horizontal eye
movement
Superior and inferior recti vertical eye
movement
Superior oblique depression during
adduction
Inferior oblique elevation during adduction

4. Nerves responsible for eye movement are:
3
rd
, 4
th
and 6
th
Their nuclei are found in the brain stem.
Together they have connections with gaze
center. And these connections ensure that both
eyes are moving together in a coordinated way.

6. Eye movements:
1. Ductions:monocular eye movement
-Vertical axis
Adduction: SR, IR, MR
Abduction: IO, SO, LR
-Horizontal axis
Elevators: IO, SR
Deppressors: SO, IR
-Anteroposterioraxis
Medial rotators: SR, SO
Lateral rotators: IR, IO

7. 2.Versions: binocular eye movement in the
same direction
Dextro=right , Levo=left
Primary position
Dextro(to the right):
Elevation: RSR+ LIO
Depression: RIR+ LSO
Version: RLR+ LML
Levo(to the left):
Elevation: RIO+ LSR
Depression: RSO+LIR
Version: RMR+LLR

8. 3. Vergences: binocular
eye movement in
opposite direction
Convergence –inward
Divergence-outward

9. Amblyopiareferstodiminishedvisionineither
oneorbotheyes.Amblyopiaisthemedical
termusedwhenthevisioninoneoftheeyesis
reducedbecausetheeyeandthebrainarenot
workingtogether.Theeyeitselflooksnormal,
butitisnotbeingusednormallybecausethe
brainfavorstheothereye.

11. Mostcasesareasymptomatic,whichmakeitoften
goesundetected.
Inseverecases:
1.poordepthperceptionmaybefound.
2.poorspatialacuity
3.lowsensitivitytocontrast
4.reducedsensitivitytomotion

12. 1.Strabismus:A misalignment of the eyes is the most
common cause of functional amblyopia. The two eyes
are looking in two different directions at the same time.
The eyes may turn in, out, up, or down. Strabismus
may be diagnosed at birth, or it may develop later in
childhood. The brain is sent two different images and
this creates confusion. Images from the misaligned or
"crossed" eye are turned off to avoid double vision.

13. 2. Refractive or anisometropic Amblyopia:A
difference of refractive states exists between
the two eyes (in other words, a difference in
prescription between the two eyes). Because
the brain cannot fuse the two images, the brain
suppresses the blurred image, causing the eye
to become amblyopic.

14. Strabismus is a condition in which the eyes are
not properly aligned with each other. It
typically involves a lack of coordination
between the extraocularmuscles that prevent
bringing the gaze of each eye to the same point
in space and preventing proper binocular
vision, which may adversely affect depth
perception. Strabismus can be either a disorder
of the brain coordinating the eyes or a disorder
of one or more muscles, as in any process that
causes a dysfunction of the usual direction and
power of the muscle.

16. why squint is important
●A squint may show that the acuity of the eye is
impaired
●A squint may itself cause amblyopia in a child
●A squint may be a sign of a life threatening condition
like retinoblastoma

17. CLASSIFICATION OF
STRABISMUS
Strabismus can be classified in terms of:
1.DIRECTION OF DEVIATION
-Hyper deviation
-Hypo deviation
-Divergent
-Convergent

18. 2. COMITANCY
-concomitant / non-paralytic
-incomitant/ paralytic
3. CONSTANCY
-constant
-intermittent

19. The movement of both eyes are full (there is no
paresis) but only one eye is directed towards
the fixated target.
The angle of deviation is constant and
unrelated to the direction of gaze.
It is the common squint that is seen in
childhood.

20. Under age of 6, it is rarely caused by serious
neurological disease. It’s usually primary in
this age group.
Strabismus arising later in life may have a
specific and serious neurological basis.

21. The degree of misalignment varies with
direction of the gaze.
One or more of the extraocular muscles or
nerves may not be functioning properly, or
normal movement may be restricted
mechanically.
This type of strabismus may indicate either a
nerve palsy or extraocular muscle disease.

22. Vascular disease..ex Dm, hypertension
Orbital disease…ex neoplasia
Trauma..most common cause of palsy of 4
th
,6th
Neoplasia… glioma
Raised intracranial pressure may cause a 3
rd
or
6
th
nerve palsy
Inflammation… sarcoidosis

23. Dysthyroid eye disease
Myasthenia gravis
Ocular myositis
Ocular myopathy
Browns syndrome

24. Heterophoria is a latent tendency for
misalignment of the two eyes that becomes a
manifest only if binocular vision is interrupted
such as by covering one eye
A minor degree of heterophoria is normal for
most individuals

25. Esotropia=inward movement
Exotropia=outward movement
Hypertropia=upward movement
Hypotropia=downward movement
prefix+phoria=(latent)the tendency to have
squint when there is no concentration on a
certain object….most common is exophoria

26. Corneal inspection
Hirschberg corneal light reflex test
Cover-uncover test

27. Have the patient look at the six cardinal
positions of gaze to differentiate between
concomitant and non-comitant

28. Objective assessment of ocular alignment
In newborn and often in young children it may
be the only feasible method
Normally the light is reflected on each cornea
symmetrically and in the same position relative
to the pupil and visual axis on each side

29. In deviating eye the light reflection will be not
centrally positioned and in direction opposite
to that of the deviation
Example…pupil margin 15’,limbus 45’,iris 30’

30. Easy, requires no special equipment and detect
almost every case of tropia
Can be used in patients >6yrs
Have the patient look at the fixation point
Note which eye seems to be fixating
Cover it and observe the other
If it moves to pick up the fixation=>this eye was
not directed toward the object of regard orginally
No shift on cover testing means there is no tropia

31. Two types of cover test help to reveal a squint, especially if it is
small and the examiner is unsure about the position of the
corneal reflections.
●In the cover and uncover test, one eye is covered and the
other eye is observed. If the uncovered eye moves to fix on
the object there is a squint that is present all the time—a
manifest squint. The test should then be carried out on the
other eye. A problem arises when the vision in the squinting
eye is reduced, and the eye may not be able to take up
fixation. This emphasizes the need to test the vision of any
patient with squint. If the cover and uncover test is normal
(indicating no manifest squint) the alternate cover test
should be done.
●In the alternate cover test, the occluderis moved to and fro
between the eyes. If the eye that has been uncovered moves,
then there is a latent squint.

36. The patient complain of diplopia, there may be
head posture to compensate for the eye to
move in particular direction.
In third nerve palsy:
failure of adduction, elevation and
depression of the eye. Ptosisin some cases, a
dilated pupil due to involvement of autonomic
fibres.
A fourth nerve palsy result in defective
depression of eye when attempted in
adduction.
A sixth nerve palsy results in faillureof
abduction of the eye.

37. Early detection
The most effective way to support
fusion(binocular vision) is to treat amblyopia
(failure of normal visual development) and
equalize vision
Glasses can treat some or all of the esotropia
In farsighted and may decrease deviation in near
sided with myopia

38. Surgical corrections of misalignment may still
be necessary for functional or cosmetic reasons
It must be stressed that surgery is not an
alternative to glasses and patching when
amblyopia
In paralytic strabimus treatment is directed to
underlying pathology
Diplopia can be helped by fitting prisms to the
patients glasses