This document discusses intermittent exotropia, providing details on its clinical characteristics, diagnostic evaluation, and treatment approaches. It notes that IXT is the most common type of exotropia, typically onset in early childhood. Control is assessed using a 5-point scale by observing the eye alignment over 30 seconds before and after dissociation. Control can vary throughout the day. Treatment may include optical correction, occlusion, vision therapy to improve fusion and reduce suppression, and in severe cases, surgery.

1. Intermittent Exotropia:
The Nuts and Bolts
Enayatollah Osroosh, student of Msc, Mashhad
University

2. ACKNOWLEDGEMENT
Susan A, Cotter, OD, MS
for use of data slides.

3.  Most common form of XT
 Onset: typically first few years of life
 Most common symptoms
• Cosmesis
• Blur
• Astenopia
• Diplopia
• Monocular eye closure in bright sunlight
• None (suppression/ARC)

4. IXT: Clinical Characteristics
Intermittent fusion
Amblyopia is rare
Good stereoacuity at near, generally
When tropic, 1 of following:
• Diplopia
• Suppression
• Anomalous correspondence

5.  Divergence excess
• Far > near angle: high AC/A
• True vs. psuedo (simulated)
 Basic
• Near = far angle; normal AC/A
 Convergence insufficiency
• Near > far angle; low AC/A

6. Follow/Treat
How can we tell if a patient is getting
worse or better?
Determine magnitude under
dissociated conditions?
Or frequency ?
• Ask parents
• In-office cover test findings
Problems with both

7. Control Score DescriptionControl Score
Observed during 2
30-sec periods, first
distance ,then near
Constant XT during a 30-sec
observation period (before
dissociation)
5
XT > 50% of the time during a
30-sec observation
period(before dissociation)
4
XT < 50% of the time during a
30-sec observation
period(before dissociation)
3
Worst of 3
consecutive trials of
covering 1 eye for
10 sec at both
distance and near
No XT unless dissociated(10
sec):recovery in >5 sec
2
No XT unless dissociated(10
sec):recovery in 1-5 sec
1
Pure phoria: < 1 sec recovery
after 10-sec dissociation
0

8.  Prior to dissociation, observe for 30 seconds:
• Constant XT= Grade 5
• XT > 50% =Grade 4
• XT < 50% = Grade 3
 Score distance and near fixation separately
 If Not spontaneously Tropic….
Move to standard dissociation phase of testing to
time “ recovery”

9. 1..2..3..4..5..6..7..8..9..10..11..12..13..14..15..16..17..18..19..20..
21..22..23..24..25..26..27..28..29..30..
XT For 10 of 30Sec (33% of 30 Sec)
<50% control score=3

10. 1..2..3..4..5..6..7..8..9..10..11..12..13..14..15..16..17..18..19..20..
21..22..23..24..25..26..27..28..29..30..
Step2:repeat 30 second observation before
dissociation at near

11. 1-2-3-4-5-6-7-8-9-10
1-2-3
4 Second
1-2-3-4-5-6-7-8-9-10
1-2-3-4-5…
6Second
score1 score2

12. Intraday Variability
 Examined 4 times over 1 day
 8:00-10:30 / 10:31-13:00 / 13:01-15:30 / 15:31-18:00
 Control assessed using control score scale
 Variable
 stable

13. Summary: Intraday Study of IXT Control
 Control varied over
1 day in many
patients
 Worst control not
always at the end of
clinical day

15.  Alternate cover test-dose not
assess “control”
 Control-problem of “sampling”-
one assessment is not enough
 Distance stereoacuity –need
multiple measures
 Near stereoacuity – often “good”
anyways

16. IXT: Other Diagnostic Evaluation
Consideration
 Cycloplegic refraction
 Cover test at remote distance
 Sensorimotor evaluation
 Distance Randot stereo test
 Worth 4 –dot when tropia is manifest
 Hering-Bielschowsky Afterimage Test when
tropia manifest?

17.  Monitor
 Refractive correction
 Occlusion
 Over-minus lens
 Prism
 Vision Therapy
 Surgery

18.  uncorrected ametropia?
 equally accommodative accuracy
 Discourage suppression
 Promote sensory fusion
 Moderate/high hyperopia consideration?

19.  IXT > 25-30 pd ???.... High recurrence rate
 post-surgical ET and loss of stereopsis
 Poor agreement on type of surgery

20.  Uses feedback
techniques/procedures
to improve fusional
vergence & sensory
fusion
 Goal is not to decrease
magnitude, but to
decrease frequency and
increase “control”
Active Vision Therapy

21. Phase 1: optical correction
Phase 2: monocular function
Phase 3: improve Sensory fusion

22.  Gross convergence
 Fusional vergence
 Anti-suppression therapy, including diplopia
awareness when XT

23.  Convergence surprise
 Pencil push up
 Brock string
 3.dot card
 Goal: Voluntary Convergence

24.  accommodation
control
Smooth fusional
vergence

25. Step fusional vergence

27. 3 to 2 to 1

28.  During active therapy
with suppression check
 Can use filters for
passive TV watching

29.  Pathological diplopia
 Use Red & Green filter in a dark
room
Flash light, Penlight, Candle
 Prism insertion/removal