Stereopsis testing in a preschool vision screening program.

We conducted a preschool vision screening study using stereopsis testing with the Random Dot E and Lang stereotests as a complement to visual acuity measurement. Over 6000 children were screened. Stereopsis testing at a threshold of 600 seconds of arc was cognitively easier for the children than visual acuity measurement. At this threshold there was no effect on reducing the rate of visual acuity overreferrals, but ten children with abnormal binocular vision were detected who were not referred by visual acuity criteria. Though a large number of children passed only one of the two stereotests, there was no significant difference in their degree of difficulty. Stereopsis testing with these two stereotests may be a useful adjunct to preschool vision screening programs though further studies are required.