This document provides information about strabismus (squint) including its definition, causes, types, and methods of examination and treatment. It defines strabismus as an ocular deviation resulting from an extraocular muscle imbalance. The main causes discussed are optical obstacles like refractive errors, sensory obstacles like uniocular vision defects, and motor obstacles involving the muscles or nerves. The document describes examining a patient for squint including testing visual acuity, eye movements, the cover-uncover test, and assessing binocular vision. It also discusses heterophoria (latent squint), paralytic squint, and treatment approaches.

1. Squint
AHMED OSAMA HASHEM
PHD,MSC, AIN SHAMS UNIVERSITY
FELLOW ROYAL COLLEGE SURGEONS.
LECTURER OPHTHALMOLOGY.

2. Strabismus or Heterotropia:
Definition:
Strabismus is simply an ocular deviation. It can be defined as an
extraocular muscle imbalance, dysfunction so that the two visual
axes do not intersect at the object of regard.

3. Etiology:
This includes obstacles that may impede the development or
maintenance of the binocular perception and fusional reflexes.
1. Optical obstacles
2. Sensory obstacles
3. Motor obstacles

4. 1. Optical obstacles
 High refractive errors
 Anisometropia (unequal refractive power)
 Anisekonia (unequal perceived retinal images)
 Opacities of the ocular media interfere with the correct formation
of images on the retinal leading,
if bilateral to nystagmus
if unilateral to concomitant strabismus.

5. 2. Sensory obstacles
Uniocular defective vision especially in infants and young children.
Care should be taken in cases of unilateral congenial severe ptosis
and also in cases of corneal ulcers in infants as prolonged occlusion
of one eye may develop strabismus.

6. 3. Motor obstacles
Muscle
Nerves
Higher control

7. Strabismus may be:
1. True
A. Manifest
1. Concomitant
a) Accommodative
1. Refractive
2. Non refractive (High A/AC ratio)
3. Mixed (Refractive and Non Refreactive)
b) Non accommodative (Essential Infantile Esotropia) since birth
c) Partially accommodative. a &b
2. Incomitant i.e thyroid eye disease .
B. Latent
2. Apparent

8. How to examine a squint case

9. How to examine a squint case
 History…
Age of onset-intermittent or constant-unilateral or alternating---history of
diplopia-trauma -fever

10. How to examine a squint case
 Visual acuity
-equality alternating squint
-unequal unilateral squint (may point out amblyopia)

11. How to examine a squint case
 External eye examination to exclude apparent squint

12. How to examine a squint case
 Slit lamp examination,,,,cornea --lens

13. How to examine a squint case
 Cycloplegic refraction is essential….
It can reveal the cause of squint – accommodative –convergence relationship.
Atropine eye drops or ointment ??

14. Special examinations:
1- Examination of ocular motility
 All extra-ocular muscles tested in 9 cardinal positions,,,
Detect limitation of movement…

15. 2-cover-uncover test
 Differentiate true (unilateral. or alternating.) and apparent squint,,,,
 It can diagnose latent squint,,,,
 The idea is to dissociate both eyes ,,
 Test should be done for near,, far with and without glasses

16. Cover test

18. Cover uncover test

19. Alternate cover test

20. 3-Measure of angle of deviation
 Simplest way :corneal light reflex

21.  Other methods measure angle :
 Prism --- synaptophore

22. Synaptophore

23. 4-Assessment of state of binocular
vision
 Synaptophore,,,,

26. Assessment of binocular functions
using Titmus fly stereotest….

27. Apparent ,,,,,

31. Visual Axis

32. Heterophoria (Latent Strabismus)
 Definition:
 Tendency of visual axis to deviate in relation to visual axis of the other eye
from normal direction ,,,,, when binocular vision is dissociated,,,
 There is usually a state of extraocular muscle imbalance which is
overcome during binocular vision by neuromuscular mechanism which
readjusts the extraocular ms to keep visual axis in order to maintain
binocular vision,,,

33.  When latent squint become manifest,,,?
A when binocular vision is removed ,,,, this is done by either covering one
eye or by special method of dissociation….

34. Type of Heterophoria
 Esophoria
 Exophoria
 Hyperphoria
 Hypophoria
 Cyclophoria : incyclophoria /excyclophoria

35. Symptoms of Heterophoria
 Asymptomatic or
 Symptomatic :
 Headaches or eye aches.
 Intermittent diplopia.
 Intermittent strabismus usually noticed by the relatives.
 Blurring of vision or running of the word into one another
while reading.
 Nausea and giddiness.
 Feeling of heavy lids, redness of the conjunctiva.

36. Etiology of Heterophoria
 High errors of refraction where myopia leads to exophoria
while hyperopia leads to esophoria.
 Minor weakness of one or more of the extraocular muscles.

37. Diagnosis of Heterophoria:
1. Cover-uncover test
2. Worth’s four dot test
3. Maddox rod and tangent scale test
4. The Maddox wing test

38. 1. Cover-uncover test

39. 2. Worth’s four dot test
five dots are seen, namely two red and three green in
cases of heterophoria.

40. 3. Maddox rod and tangent scale
test

41. 4. The Maddox wing test

42. Treatment of heterophoria
1. Cases without symptoms
 No treatment
2. Cases with symptoms
 Accurate correction of any refractive error may alleviate the symptoms.
 Orthoptic training for horizontal phorias may be tried before prisms.
 The use of prisms.
 Surgical correction is indicated when the other modalities fail to correct
the latent deviation.

43. Paralytic strabismus
 Incomitance means that the angle of deviation is not the
same in all directions of gaze.
 The deviation increases in the direction of action of the
affected muscle and decreases in the direction of action of
the antagonist.

46. Etiology
It is due to a lesion anywhere between the nuclei of the third, fourth and
sixth cranial nerves and the muscles themselves. The lesions may be due any
of the following causes:
1. Congenital absence of the nerve nucleus or absence of the muscle its
malinsertion.
2. Traumatic, either affecting the muscle or its nerve supply.
3. Inflammatory, encephalitis, neuritis or DS.
4. Vascular, cerebral hemorrhage or thrombosis.
5. Toxic, alcohol, lead poisoning or diphtheria toxins.
6. Neoplastic, a tumor pressing on the nerve supply of the muscle.
7. Myogenic, myasthenia gravis, thyrotoxic myopathy or ocular myopathy.

47. Symptoms
1. Binocular diplopia
2. Deviation
3. Vertigo
4. Abnormal head posture
5. Past pointing

48. Signs
1. Deviation of one eye
2. Limitation of ocular movement
3. The secondary angle of deviation
4. Compensatory head posture

49. Deviation of one eye XT

51. . Abnormal head posture
This posture is adopted to avoid diplopia and
distressing effects

53. 3. The secondary angle of deviation
is greater than the primary angle of deviation.
The primary angle is the deviation elicited
when the patient fixes with the sound normal
eye
The secondary angle is the deviation elicited
when the patient fixes with the affected eye.

55. Paralysis Of Individual Ocular Muscles:
1. Clinical picture of lateral rectus palsy (Abducent
nerve palsy)
2. Clinical picture of third nerve palsy
3. Clinical picture of trochlear nerve palsy

56. 1. Clinical picture of lateral rectus palsy
(Abducent nerve palsy)
 Esotropia in the primary position.
 Limitation of abduction.
 Esotropia increases on looking to the affected
side.
 Secondary angle deviation is greater than the
primary angle.
 Uncrossed diplopia.
 Face turn to the side of the affected muscle.

58. 2. Clinical picture of third nerve palsy
 Ptosis is present and may mask diplopia if the lid
covers the pupillary area.
 Limitation of elevation, depression and
adduction.
 Large angle exotropia.
 Pupil may be dilated and fixed.
 Paralysis of accommodation with difficult near
work.
 Crossed diplopia.

60. 3. Clinical picture of trochlear nerve
palsy
 Head tilt to the opposite shoulder.
 (chin depression)if bilat.
 Limitation of downward and inward
movement.
 Hypertropia if the head is forced to tilt to the
same side shoulder
 Hypertropia when looking to the opposite
side.

61. Treatment of paralysis strabismus
The aim of treatment is as follows:
 To restore comfortable binocular single vision over as a large an area as
possible.
 To make the ocular movement as symmetrical and equal as possible.

62. General principles in management of
paralytic strabismus:
Treatment of the cause should be tried at first.
It is advised to wait for 6 months before deciding to correct the deviation
surgically.
Surgical treatment is indicated when there is no hope of recovery (after 6
months of stability of the condition) and before development of the
secondary changes as direct antagonist.
The contralateral antagonist might be strengthened. For example, in cases
with lateral rectus paralysis, the direct antagonist that is the medical rectus
should be recessed.
Resection of the effected muscle may be of help if the paralysis is not be
help and in such cases muscle transposition is indicated.

64. Thank You