Abstract
Purpose: :
Distance stereoacuity data may be useful in assessing strabismic patients who have differences in the distance and near angle of deviation, including intermittent XT. We developed the Distance Randot® Stereotest as an easily administered quantitative test for distance stereoacuity in children as young as four years of age. Using a prototype, we previously reported extensive testability, validity, and normative data. Here we report normative and validity data for the final, commercially available version of the test.
Methods: :
The Distance Randot® is a Polaroid vectographic book, presenting 2 shapes at each of 4 disparities: 400, 200, 100, and 60 arcsec viewed at 3m through polarizing glasses. The smallest disparity level at which the child can identify both shapes is recorded as stereoacuity. We administered the Distance Randot® to 31 normal volunteers (4-36 y) and 39 strabismic patients (4-73 y). The prototype distance stereoacuity test was also administered. Test-retest data were collected for the final version of the test.
Results: :
Normative Distance Randot® scores were similar to those obtained with the prototype; 96.8% of normal scores were ≤100 arcsec. Test-retests were identical in 71% and within one disparity level in 96.8%. Among strabismic patients, 79.5% had abnormal Distance Randot® scores; the few with normal scores had incomitant or intermittent deviations. Nil stereoacuity was found in 22 patients and confirmed in 90.9% of retests; 17 had measureable stereoacuity, confirmed in 91.4% of retests. Patients with constant ET or XT (n=16) were more likely to have nil stereoacuity than patients who had intermittent ET or XT (n=15)(100% vs 20%; z=7.75, p<0.001). Overall, Distance Randot® scores were highly correlated with prototype scores (rs = 0.90, p<0.001).
Keywords: binocular vision/stereopsis • strabismus