Visual acuity of infants with ocular diseases.

We tested the visual acuities of 110 infants with ocular disorders by a preferential-looking technique that provides fast, accurate measurements for preverbal children. The results were used to confirm initial clinical evaluations and to prescribe and monitor treatment. The test was particularly helpful in assessing the effects of occlusion therapy. The child sat on a parent's lap 50 cm away from a black partition containing two circular screens. A grating was projected on one screen and a homogeneous field was projected on the other. A hidden observer watched the infant's eye and head movements to determine which screen was preferred.