Visual rehabilitation after long lasting early blindness.

A 23-year-old woman, blinded at an early age due to retinopathy of prematurity and cataract was successfully operated. After the operation the patient was behaviourally blind. Visual rehabilitation was started 9 months later and lasted 1 1/2 years. During this time the visual behaviour of the patient improved. Quantitative tests were designed to depict the progress. The functional improvement of the patient is in agreement with the findings of animal studies; binocular deprivation during the critical period of development causes behavioural blindness, which is partially recoverable. The result of this study indicates that the visual rehabilitation facilitates the process of recovery. The progress in visual behaviour is likely to reflect an improvement of the function of the associative systems of the brain.