PROPORTION OF TIME OF BINOCULAR ALIGNMENT IN PATIENTS WITH INTERMITTENT EXOTROPIA Bruce Wick. James Pietrantonio.

Title PROPORTION OF TIME OF BINOCULAR ALIGNMENT IN PATIENTS WITH INTERMITTENT EXOTROPIA Bruce Wick. James Pietrantonio.
Author, Co-Author Bruce Wick
Topic
Year
1992
Day
Saturday
Program Number
2:15 pm
Room
Scotland A
Affiliation
Abstract Intermittent exotropia (IXT) accounts for approximately 45% of the cases of strabismus. The typical patient with IXT shows normal binocular alignment and sensory fusion part of the time, with recurrent intervals of disrupted fusion when one eye turns outward. The proportion of time that ocular alignment is maintained can be estimated with many clinical techniques but the unilateral cover test is used most commonly. Unfortunately, the accuracy of the cover test is questionable for this purpose because the proportion of time that an IXT occurs varies due to attentional factors, fatigue, illumination, and refractive correction, as well as inconsistencies in performing the test itself. We have refined a video recording method using a television-based Eyetracker (DBA Systems Model 606) that allows objective determination of the magnitude of a deviation (to within +0.5[prism diopter sign]) and the proportion of time that binocular alignment occurs. We used this system to quantify objectively, with computer decision, the proportion of time binocular alignment occurred for 6 patients believed to have IXT. Measures were made for each patient at two separate 30 minute times during the day under three different conditions (distance viewing, reading, and looking at a uniform field with reduced fusion contours). The results suggest that for IXT patients, who are often easily dissociated when an eye is occluded, the cover test provides a lower estimate of the proportion of time that binocular alignment is maintained than the actual time that may occur in everyday life. This approach to assessing the proportion of time that the deviation occurs in patients with intermittent exotropia looks promising for general clinical use and as an outcome measure in a proposed clinical trial concerning the efficacy of vision therapy as treatment of IXT. NEI R21 EY 00282 (BW)
Affiliation of Co-Authors
Outline