Distance stereoacuity norms for the mentor B-VAT II-SG video acuity tester in young children and young adults

Abstract

Purpose: The purpose of this study was to provide normative distance stereoacuity data for the Mentor B-VAT II-SG video acuity tester (Mentor O & O, Norwell, Mass.). Methods: Near and distance stereoacuity for 45 normal young children (5 to 6 years old, child group) and 67 normal young adults (16 to 20 years old, adult group) were evaluated. Distance stereoacuity was measured with the Random Dot and the Circles tests on the B-VAT unit. Near stereopsis was assessed by Titmus, Randot, and TNO tests. Additionally, a random subset of the subjects was retested 1 month later with the B-VAT unit. Results: The mean and SD values of stereoacuity measured on the Circles and Random Dot tests were 49 ± 33 and 98 ± 49 seconds of arc in children (p < 0.0001) and 50 ± 32 and 83 ± 51 seconds of arc in adults (p < 0.0001), respectively. No significant differences were found between the same tests with respect to age. Of 112 subjects in both groups, 110 (98%) achieved 120 seconds of arc or finer stereoacuity threshold levels on the Circles test and 108 (96%) demonstrated 180 seconds of arc or finer scores on the Random Dot test. Although all but two of the subjects exhibited stereopsis both at near and at distance, there were low correlations among the different near and distance stereotests. Test and retest distance stereoacuity scores agreed closely. Conclusions: The B-VAT II-SG system produces reliable distance stereoacuity data. The norms we obtained may aid the clinician to detect binocular visual disturbances or may provide a basis for using distance stereoacuity as a screening method. Copyright © 1998 by the American Association for Pediatric Ophthalmology and Strabismus.