Lack of short-latency-potentials in the VEP reflects immature extra geniculate visual function in delayed visual maturation (DVM)

Purpose: To investigate children with delayed visual maturation (DVM) and c orrelate the electrophysiological findings to visual development. Methods: Three children, one from each of the DVM-classification groups, were subjec ted to routine ophthalmological examinations and electrophysiological exami nations: flash visual evoked potential (VEP) and skin electrode electroreti nography (ERG). Results: All three children had normal ERGs but initially a bnormal VEP-recordings with marked delay of latency or grossly altered VEPs . When visual interest developed with responsive smiling at 4, 4.5 and appr oximately 12 months of age, a maturation in the VEPs also appeared, with de velopment of a short-latency complex (approximate to 70 ms). In the normal neonatal development of the VEP, a negativity at approximately 60-70 ms (N1 ) emerged at four to six weeks of postnatal life when the child started res ponsive smiling and showing raised visual interest. According to animal exp erimental research and human studies, the development of the specific respo nse (the short-latency complex) represents the gradual onset of cortical ac tivity mediated via the specific retino-geniculo-striatal pathway. Thus, wh en the short-latency complex of the VEP cannot be identified, the visual fu nction is mainly of subcortical origin. Since the VEP developed in the same way in the children with DVM as in normal subjects, the patophysiological dysfunction and origins of DVM can pal-try be understood. Conclusions: The results show that i) children with DVM has a period of visual inattentivene ss at a time when normal children show visual interest, ii) the VEP is abno rmal in children with DVM at the time of visual inattentiveness, iii) the i mprovement of vision in DVM can be measured with VEP and iiii) the extra-ge niculate system(s) provides for the visual function early neonatally in the normal child and in a prolonged period in the DVM-child as long as the VEP s are abnormal.