[Normal and defective development of visual stimulus processing: psychophysical and electrophysiologic test results].

Two methods were developed for the assessment of normal and disturbed visual development in infancy and early childhood: the preferential looking procedure (PL) as a psychophysical method and measurement of visual evoked potentials (VEP) as an electrophysiological principle. Both methods test visual functions, but on different levels of the visual system. Proper interpretation of the methods requires direct comparison. This was accomplished over a 12-months period in infants and young children with normal and disturbed visual development in the first year of life. For normal infants older than 4 weeks we found accurately configurated VEP responses and rapidly increasing visual accuity, ranging from 0.4 cpd (age 2.5 weeks) to 10 cpd (36 weeks) and better. There was a close agreement between the VEP and PL results, possibly due to our conservative interpretation of VEP acuity, which was not extrapolated from the VEP amplitude versus spatial frequency function, but defined by the relationship to the simultaneously registered noise level of the responses. The last response that could be differentiated from this noise level was defined as VEP acuity in analogy to the acuity definition of the Teller acuity cards. In visually impaired children there was a delay in visual development. Visual deficits in congenital cataract were much more marked than in congenital squint. Infants with congenital cataract showed a nearly newborn stage when tested shortly after lensectomy. With our preliminary results is was not possible to determine any statistical relationship among the psychophysical, electrophysiological and clinical findings.(ABSTRACT TRUNCATED AT 250 WORDS)