DISTANCE STEREOACUITY - ASSESSING CONTROL IN INTERMITTENT EXOTROPIA

Background: A patient's ability to control an intermittent exotropic d eviation is usually assessed by subjective means such as observation o f control in the office, questioning the patient and/or family about c ontrol at home, and reports of monocular eye closure in bright light. An objective method of assessing control has not been developed. Purpo se: The purposes of this study are to determine if distance stereoacui ty was different in patients with intermittent exotropia than in norma l subjects and to determine if distance stereoacuity could be used as a objective means of assessing control in intermittent exotropia. Meth ods: The authors evaluated near and distance stereoacuity in 44 patien ts with intermittent exotropia and 50 normal subjects. Patients with i ntermittent exotropia also were assessed for office control, home cont rol, and monocular eye closure in bright light. Additionally, six pati ents who underwent successful surgery were reevaluated postoperatively . Conclusion: Normal subjects and patients with intermittent exotropia had good near stereoacuity. Patients with intermittent exotropia demo nstrated significantly worse distance stereoacuity than the population of normal subjects (P < 0.001). Five of six patients with poor distan ce stereoacuity preoperatively had dramatic improvement in distance st ereoacuity postoperatively. Diminished distance stereoacuity seems to be an objective measure of poor control of the exotropic deviation. Th is test may provide important objective criteria for deciding when to perform surgery in patients with intermittent exotropia.