Abstract
Purpose::
Infantile esotropia is associated with maldevelopment of cortical visual motion processing, as manifested by nasotemporal asymmetry of motion visual evoked potential (motion VEP) responses. The purpose of this study was to determine how early versus delayed repair of infantile esotropia influences the development of motion VEP in human infants.
Methods::
Children with infantile esotropia ≥ 40 prism diopter and onset before age 6 months were recruited prospectively. They underwent surgical correction between 4 to 18 months of age. At age 2 years, motion VEPs were elicited during monocular viewing using two oscillating sine wave gratings separated by 90° at 11 Hz. Asymmetric (F1) and symmetric (F2) frequency components were extracted from the motion VEP responses. Two methods were used to determine the presence of a nasotemporal asymmetry: the magnitude of the Asymmetry Index, which was defined as the ratio F1/(F1 + F2) and the phase difference between F1 and F2.
Results::
Preliminary data were collected from 10 children who underwent surgery between 6 and 18 months of age. Mean Asymmetry Index was 0.44±0.27 in infants who were surgically aligned by 12 months of age (n=5 and it was 0.74±0.08 in those who were aligned at 12 to 18 months of age (n=5) (t-test, p=0.04). The difference in phase between F1 and F2 was significant different between the two patient groups (t-test, p=0.01).
Conclusions::
Early surgery for infantile esotropia may prevent maldevelopment of cortical visual motion processing. More patients are being recruited for this ongoing prospective non-randomized trial.
Keywords: strabismus: treatment • visual development: infancy and childhood • esotropia and exotropia