FLASH VISUAL-EVOKED RESPONSE BINOCULAR SUMMATION IN NORMAL SUBJECTS AND IN PATIENTS WITH EARLY-ONSET ESOTROPIA BEFORE AND AFTER SURGERY

Flash visual evoked responses were recorded and visual evoked response binocular summation was assessed in normal children between the ages of 1 and 58 months, in normal adults and in children with early-onset esotropia before and longitudinally for 1 year after surgical binocula r alignment. Normal flash visual evoked response binocular summation s tarted in the range of facilitation (> 2.0) at 1 month of age and decr eased to adult levels by 3.7 months of age. The shape of the hash visu al evoked response binocular summation function obtained from the pati ents with early-onset esotropia, appeared similar to that of normal su bjects; however, the rapid decrease in flash visual evoked response bi nocular summation from facilitation to normal adult levels occurred af ter surgical binocular alignment. In normal adults, flash visual evoke d response binocular summation was significantly reduced by a 40-diopt er base-in prism, suggesting that binocular misalignment was not the r eason for the facilitation in flash visual evoked response binocular s ummation in either childhood population. It is proposed that this faci litation may reflect a process that leads to binocularity and that dev elops rapidly with binocular alignment.