The development of binocular function in infancy

Binocular function in infancy can be assessed by means of the visual evoked potential (VEP) induced by a dynamic random dot pattern which alternates between a binocularly correlated and an anticorrelated state. A VEP time-locked to the alternation can only be produced by binocular interaction in the cortex. This interaction becomes detectable at around three months of age. Optokinetic nystagmus (OKN) in monocular viewing becomes symmetrical in nasal and temporal directions around the same age. Animal analogues and clinical cases suggest that this may also be an indicator of cortical binocularity. These techniques may be applicable to clinical assessment of binocular function in young infants.