Delayed visual maturation: ophthalmic and neurodevelopmental aspects.

Delayed visual maturation (DVM) can present as an isolated anomaly (type 1A), but can be compounded by perinatal problems (type 1B), severe neurodevelopmental delay (type 2), or ocular anomalies/nystagmus (type 3), in which group the common feature appears to be nystagmus. The neurodevelopmental and ophthalmic aspects of 26 infants with DVM were studied. Onset of visual improvement, rate of acquisition of normal vision and eventual outcome were studied quantitatively, using an adaptation of the acuity card procedure. Neurodevelopmental assessment was performed after visual improvement. The results support the long-held clinical impression that if blindness is the presenting feature, neurodevelopmental outlook is excellent. DVM could represent a defect in the extrageniculostriate visual system, and the onset of vision in all types--and the development of nystagmus in type 3--could herald the emergence of geniculostriate function.