DELAYED VISUAL MATURATION IN INFANTS - A DISORDER OF FIGURE-GROUND SEPARATION

Delayed visual maturation (DVM) is characterised by visual unresponsiv eness in early infancy, which subsequently improves spontaneously to n ormal levels. We studied the optokinetic response and recorded pattern reversal VEPs in six infants with DVM (aged 2-4 months) when they wer e at the stage of complete visual unresponsiveness. Although no saccad es or visual tracking with the eyes or head could be elicited to visua l objects, a normal full-field rapid buildup OKN response occurred whe n viewing biocularly or during monocular stimulation in the temporo-na sal direction of the viewing eye. Almost no monocular OKN could be eli cited in the naso-temporal direction, which was significantly poorer t han normal age-matched infants. No OKN quick phases were missed, and t here were no other signs of ''ocular motor apraxia.'' VEPs were normal in amplitude and latency for age. It appears, therefore, that infants with DVM are delayed in orienting to local regions of the visual fiel d, but can respond to full-field motion. The presence of normal OKN qu ick-phases and slow-phases suggests normal brain stem function, and th e presence of normal pattern VEPs suggests a normal retino-geniculo-st riate pathway. These oculomotor and electrophysiological findings sugg est delayed development of extrastriate cortical structures, possibly involving either an abnormality in figure-ground segregation or in att entional pathways.