Monocular acuity and stereopsis in infantile esotropia.

Monocular acuity and stereopsis were assessed by preferential-looking procedures in untreated infantile esotropes. Results were compared to an age-matched normal population. Monocular PL acuity was not significantly different from normal during months 3-14 for infantile esotropes who freely alternated fixation and for the preferred eyes of unilateral infantile esotropes. PL acuity of the non-preferred eyes of unilateral esotropes was significantly below normal during months 9-14, but not during months 3-8. The percentage of normal and esotropic infants who demonstrated PL stereopsis was approximately equal at 3-5 months but, unlike normal infants, the percentage of esotropic infants demonstrating stereopsis was lower in the older age groups. Taken together, the acuity results support previous reports that deficits in PL acuity develop after the onset of fixation preference. The results of PL stereopsis testing are consistent with the hypothesis that stereoscopic pathways are present and potentially functional in at least some esotropic infants.