Intermittent exotropia

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  • 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) 25-30 pd ???.... High recurrence rate post-surgical ET and loss of stereopsis Poor agreement on type of surgery 19. 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 20. Phase 1: optical correction Phase 2: monocular function Phase 3: improve Sensory fusion 21. Gross convergence Fusional vergence Anti-suppression therapy, including diplopia awareness when XT 22. Convergence surprise Pencil push up Brock string 3.dot card Goal: Voluntary Convergence 23. accommodation control Smooth fusional vergence 24. Step fusional vergence 25. 3 to 2 to 1 26. During active therapy with suppression check Can use filters for passive TV watching 27. Pathological diplopia Use Red & Green filter in a dark room Flash light, Penlight, Candle Prism insertion/removal