VECP evidence for binocular function in infantile esotropia.

Since commonly used clinical methods of measuring binocular function require subjective responses, this testing has been limited to more cooperative children, usually older than 2 years of age. Recently, we have begun using a clinically practical, visually evoked cortical potential (VECP) method to detect the presence of binocular neurons in infants and young children. We studied 14 children, ages 4 to 44 months, with infantile esotropia. Nine had surgical correction for esotropia by the age of 2 years. Twenty-five normal infants ages 6 weeks to 22 months served as controls. Most normal infants showed the development of the "beat" by 2 months of age. The "sum" VECP was not consistently present until age 6 months. Four of the five esotropic infants less than 1 year of age, demonstrated neither a "sum" nor "beat" response. All nine patients with corrective surgery performed before 2 years of age developed a significant sum response and three developed a beat. Five patients had not had surgery until after 2 years of age. Two developed a sum and one a beat, but none had both beat and sum responses. The results suggest that there is a loss of nonlinear binocular response in esotropic children not corrected before the age of 2 years and that these responses can be restored after early treatment even if not present at the time of surgery.