2. Strabismus is the condition when
visual axes of two eyes do not meet at
the point of fixation
3. • Comitant: Although misaligned they retain relation in all direction of
gaze
• Incomitant: Deviation is different in all position of gaze
• Tropia: It is manifest ocular misalignment
• Phoria: It is latent ocular deviation
• Alternate : Fixation is retained by alternate eye
• Unilateral: Only one eye habitually fixes
• Intermittent: when deviation remain only for some time
4. Tropia or Phoria can be
• Esotropia /phoria
• Exotropia/phoria
• Hypertropia/phoria
• Hypotropia/phoria
• Cyclotropia/phoria
5. Children at risk
• Consanguinity
• Positive family history
• Pre mature and LBW
• Smoking during pregnancy
• Chromosomal abnormalities - DRS
• Uncorrected refractive error
• Cerebral palsy
6. History
A careful history is important in the diagnosis
• Mother's Obstretical history
• Birth history
• Drug history
• Family history
• Developmental milestones
• Any trauma, especially to head or face
7. History..
• History of presenting complaints
• Age of onset
• Sudden or gradual
• Constant or intermittent
• Present for distant or near or both
8. History..
• Unilateral or alternating
• Is it present only when the patient is inattentive or fatigued
• Association with trauma or physical stress
• Old photographs
• History of previous therapy/Rx received
• General health
9. Examination
• Vision test
• Refraction
• Evaluation of strabismus
• Assessment of binocular vision
• Detailed ophthalmic evaluation
• Special test
17. Cover tests
• Cover/uncover test
-one eye is covered and observe the movement of uncovered eye to
take up fixation
-position and movement of the covered eye, as the cover is removed
18. Cover tests..
• Alternate cover test
-one eye or the other is covered throughout the test;
- the movement of the covered eye is noted as the cover is changed
from one eye to the other
20. Information provided by the cover test
• Direction of the deviation
• Difference in the angle from near to distance fixation
• Effect of accommodation
• Patients refractive error
• Comitance or incomitance
21. Information provided by the cover test
• Characteristics of manifest strabismus; constant or intermittent;
unilateral or alternating
• Speed of recovery
• Presence of latent nystagmus
22. Recording results of the Cover test..
• Type of deviation; whether manifest or latent
• Direction of deviation ; Horizontal, vertical or combination of the two
• Which eye deviates
• Estimation of size
• Any special features ; incomitance, nystagmus, DVD
23. Prism cover test
• It combines the alternate cover test with prism
• Indication: measure the angle of total deviation
• Apex of the prism always placed towards the deviation
24. Prism cover test..
Technique:
• First alternate cover test performed
• Prism of increasing strength are placed in front of one eye
• Alternate cover test continuously performed
• As stronger prism are brought
25. Prism cover test..
• Amplitude of re-fixation movement gradually decrease
• At a point no movement is seeing
• Increased prism power until movement is in the opposite direction
• Then reduce prism power to find the neutral value.
27. Corneal reflex tests
Krimsky test:
• A prism bar is placed in
front of the fixating eye
• The power increased
• Until the reflections get
symmetrical.
28. Corneal reflex tests…
• Prism reflection test:
Involves placement of prisms in front of deviating eye
The power increased
Until the reflections are symmetrical
30. Maddox rod test:
Orthophoria: streak passes
through white light.
If streak passes on the left to
the light i.e. esophoria &, if
to the right then exophoria
35. Ocular motility..
Information recorded must include:
• Whether movement is full, limited , or excessive
• Grade of abnormality,usually-4 to+4
• Direction of abnormality
• Any associated signs , like lid changes or presence of nytagmus
36. Ocular motility..
Grading of limitation and overaction:
• Limitation is usually graded on a scale of -1 to -4
• -4 indicate there is no movement beyond the midline
• -3 indicates that 25% movement remains,
• Over action is graded from +1 to +4
37. Ocular motility..
• Near point of convergence:
Nearest point on which eye can maintain binocular fixation.
Measured by RAF rule
It should be Less than 10 cm.
• Near point of accommodation:
Nearest point on which eyes can maintain clear focus.
39. Evaluation of BSV..
Aims of evaluation of binocular function
To determine if the aim of treatment should be restore
binocular single vision or to improve the patients appearance
and ensure that s/he has the best possible visual acuity
49. PARK’S 3 step test:
• Use to identify cyclovertical muscle paralysis.
• Performed by measuring the vertical alignment in
1)primary position,
2) In right and left gaze and
3) In head tilt to the right and to the left.
50. Forced duction test:
Anesthetize the eye
Lids retracted
Patient looks in the direction of the muscle tested
Globe hold at the opposite limbus with forcep
Eye is rotated at the direction of action of muscle
51. Forced duction test:
Result:
• If free movement is present then the test is negative
• If restricted then the test is positive
52. Take Home message
• Time consuming
• Needs Patience specially for intermittent exotropia
For children
• Poor cooperation
• Lack of subjective response
Challenges