Vision Screening with Random Dot Stereograms

Abstract

Preschool vision screening programs using visual acuity criteria as the basis for referral are hampered by untestability, overreferral and probable underreferral. Contour-type stereograms have failed as alternatives to visual acuity testing. Random dot stereograms have shown more promise as alternatives or supplements to visual acuity testing. The stereoacuity threshold at which a random dot stereogram achieves an acceptable level of testability among preschool children and yet reliably detects amblyopiogenic conditions such as anisometropic amblyopia is a key issue. For the Random Dot E stereotest, we have found that testability rates for children from 2 to 6 years old drop off sharply at 126 seconds of arc as compared to 168 seconds of arc. A threshold of 168 seconds of arc has an acceptable rate of testability but has not yet been shown to be a reliable level for amblyopia detection. We are currently conducting a randomized clinical trial to determine whether stereoacuity testing at this threshold is a valuable supplement to visual acuity testing in improving testability and referral accuracy.

• amblyopia
• anisometropia
• stereopsis
• visual acuity
• vision screening