This document discusses strabismic amblyopia, including its definition, causes, diagnosis, and treatment methods. Strabismic amblyopia is a type of amblyopia or "lazy eye" caused by strabismus or misalignment of the eyes. It occurs when one eye is favored for fixation over the other due to strabismus, leading to reduced visual acuity in the non-fixating eye. Diagnosis involves testing for differences in visual acuity between the eyes. Treatment may include vision therapy, eye exercises, or surgery to correct the strabismus, with the goal of improving visual acuity in the amblyopic eye.

1. UNIVERSITY OF
GONDAR
COLLEGE OF MEDICINE AND
HEALTH SCINCES
DEPARTMENT OF OPTOMETRY BINOCULAR
VISION
Strabismic ambylopia
By Group 3
December 4 /2017

2. OUTLINE
 definition of ambylopia,
strabismic ambylopia
 causes of strabismic ambylopia
 diagnosis methods
 treatment

3. SENSORY ADAPTATIONS
 sensory adaptation s are the mechanisms by which
any abnormality to binocular vision is
componsated .
 Can be classified as binocular and monocular
 binocular ,1ARC
2 Suppression
Monocular sensory adaptations are :-
a, strabismic ambylopia and
b, eccentric fixation.

4. DEFINITION
 The definition of amblyopia(lazy eyes) is ‘reduced visual
acuity not correctable by refractive means and not
attributable to obvious structural or pathological ocular
anomalies.
 Functional reduction in VA of an eye caused by disuse d
uring the critical period of visual development.
 A visual loss resulting from an impediment or disturban
ce to the normal development of vision.
 The anatomy of the eye is intact or normal but it is
lazy causing dullness of vision(reduction in visual
acuity).

5. FUNCTIONAL AMBYLOPIA
Catagory of ambylopia where no organic lesion exists: on eye
exam a deficiency of form vision affecting either one or
both eyes
1) Strabismic amblyopia
2) Deprivation amblyopia:
3) Occlusion amblyopia
4) Anisometropic amblyopia
5) Isoametropic amblyopia
6) Psychogenic amblyopia

6. STRABISMIC
AMBLYOPIA
 Patients with strabismus who strongly favor one eye for fixation and
who have a unilateral rather than an alternating fixation pattern are
most likely to acquire strabismic amblyopia.
 occurring generally before the age of seven years, which cannot be
corrected purely by accurate refraction.
 It should not be associated with any recognizable pathological caus
e, but should be attributable to an amblyogenic factor.
 Strabismic amblyopia represents a loss of the physiologic superiorit
y of the fovea. This superiority is characteristic of the photopic state
. The amblyopic eye is functionally at its worst at photopic luminan
ce levels, at which point the foveae of these eyes display certain char
acteristics of the dark-adapted state.

7. CAUSE OF STRABISMIC AMBYLOPIA
 As the name indicates the main cause of this ambylopia is
strabismus. especially esotropic pxs are likely to dev’p strabismic
ambylopia, Patients with exotropia frequently are able to
alternate fixation, which greatly minimizes their risk of
developing amblyopia.
 In esotropia the fovea of the deviating eye has to compete with
the strong temporal hemifield of the fellow eye. In exotropia
the fovea competes with the weaker contra lateral nasal
hemifield.
 Strabismic amblyopia is always unilateral and is caused by active
inhibition within the retinocortical pathways of visual input
originating in the fovea of the deviating eye. This inhibition is
the consequence rather than the cause of strabismus and is
elicited by overlap of the different foveal images transmitted to
the visual centers from the retinas of the fixating eye and the
deviating eye.

8. CONTINUED
 The etiology of strabismic amblyopia is similar to that
of suppression. However, whereas suppression is
restricted to binocular vision, and the visual acuity of
each eye, when measured monocularly, is normal,
amblyopia exists under binocular and monocular
conditions. Thus amblyopia may be considered a
carryover of suppression into monocular .However,
amblyopia may also occur occasionally in strabismus
without suppression of the fovea of the deviated eye.
Thus, suppression alone cannot always be the cause of
amblyopia.

9. CONT…
 Surgery :-In patients with infantile esotropia and no
amblyopia, surgical correction increases the risk of
developing amblyopia.
 Amblyopia will develop if the child has a preference
for one eye.dis use may develop ambylopia to the eye
.

10. PATHOPHYSIOLOGY/CLINICAL FEATURES
Mechanism originates in visual cortex.
Decrease in number of binocularly driven cells in striate
cortex.
Reduction in cortical blood flow and glucose metabolism
Causes reduction in V.A, binocularity, dark adaptations, V.F
defects, contrast sensitivity, spatial localisation, fixation, oc
ular motility, accommodation, crowding, attention, m
otion perception and temporal processing.
Therefore fusion and streopsis that depend on clear image
from each eye simultaneously are affected .

11. VISUAL ACUITY
 Any difference in acuity between the two eyes
represents an amblyopia of the eye with the poorer
vision.
 Strabismic amblyopia has been found to be caused by
active inhibition within the retinocortical pathways
of visual input originating in the fovea of the
deviating eye. This inhibition is elicited by overlap of
the different foveal images transmitted to the visual
centers.
 There will be low speed of reading small font sizes,
more saccadic mov’t and ocular motion reduction.

12. DIAGNOSIS
 From a practical clinical standpoint, a difference of
two lines on a visual acuity chart is commonly
used as a diagnostic criterion for amblyopia. any and
every difference in visual acuity produced by
amblyopiogenic factors should be classified as an
amblyopia.
 Low visual acuity in one or both eyes out of
proportion to the structural abnormality of the eye
and excluding other visual disorders as causes for
lowered VA. it can be defined as an intra ocular
difference of two lines or more in acuity.

13. CONT...
 Random dot stereo test:- Strabismic
amblyopia may be detected by tests assessing random
dot Stereopsis. Which consists of a random dot
stereogram upon which a series of parallel strips of
cylindrical lenses are imprinted in certain shapes,
which separate the views seen by each eye in
these areas without stereopsis ,the image looks like
a field of random dots but the shapes become
discernible with increasing stereopsis.
 The image should be at 40 cm and exactly in the
frontoparallel plane.

14. CROWDING PHENOMENON
 In patients with amblyopia, it is always importance to
compare the vision obtained with visual acuity symbols
presented in a row, to that obtained with isolated
symbols on a uniform background. Many patients with
amblyopia are capable of discriminating rather small
visual acuity symbols when they are presented singly
against a uniform background, whereas when presented
in a row, as on a visual acuity chart, the symbols must
be larger, often considerably larger, for a patient to be
able to recognize them with the amblyopic eye.

15. TREATMENT METHODS
 Strabismic ambylopia should be detected as early
as possible to treat it successfully. especially if
detected before the age of 5 the underlined cause is
corrected with glasses or surgery.
 There are different treatment methods including
1. vision therapy
2. orthopic exercises
3. surgery

16. VISION THERAPY
 A type of physical therapy for the eyes and brain ,highly
effective ,non surgical treatment. it involves :-
 progressive program of vision exercises or procedures
. Twice a week for 30 minutes.
 supervision by professional
 Therapeutics lenses
 Prisms
 Optical filters
 using an occuludor or eye patch

17. CONT...
 The normal eye is covered by occuludor or get
pharmacological penalization by atropine drops to
temporarily paralyze accommodation reflex ,this
blurs he vision of the normal eye repetitive action of
this tends the amblyopic eye to improve it’s VA.
 N.B don’t continue to practice this if not it bring
some improvement until 6 months ,b/s “reverse
ambylopia” may develop.

19. WHEN AND HOW TO TREAT STRABISMIC
AMBYLOPIA?
 Research has shown that early surgical alignment is
associated with better stereopsis in those patients with
infantile esotropia treated in the first 24 months of life,
because early surgery minimizes the duration of
misalignment. However, in patients in which the
strabismus is accompanied by amblyopia
preoperatively, caregivers must decide whether to treat
the strabismus or amblyopia first. Treating the
strabismus first will decrease the length of
misalignment and possibly increase the chance of some
degree of binocularity. Treating the amblyopia first will
potentially give the patient better vision in each eye,
which may aid the stability of the postsurgical
alignment.

20. IF YOU GOT US
1. What is ambylopia and what about strabismic
ambylopia?
2. List some causes of strabismic ambylopia ?
3. How can you diagnose this ambylopia ?
4. list at least two treatment methods for strabismic
ambylopia ?

21. FOR FURTHER UNDERSTANDING
REFERENCES
1. von Noorden GK. Binocular Vision and Ocular
Motility: Theory and Management of Strabismus…
2. Hoyt CS: Amblyopia: Aneuro-ophthalmic view. J
Neuroophthalmol2005; 25: 227–231.
3 American orthopic journal volume 57,2007

22. Thank you