Longitudinal study of acuity and stereopsis in infants with or at-risk for esotropia.

Grating acuity and stereopsis were measured longitudinally in five groups of infants: infantile esotropes, moderate hyperopes, high hyperopes, infants with a family history of strabismus or amblyopia and controls. Grating acuity was measured with a forced-choice preferential looking procedure. Stereopsis was assessed with a random-element stereogram. Testing was conducted when subjects were 3, 6, 9, 12, 18, 24, 30 and 36 months of age. No differences among groups in absolute acuity scores or interocular acuity differences were found until the infants reached 30 and 36 months of age. At these ages, treated infantile esotropes showed acuity scores that were, on average, 0.5 octave poorer than those of controls for both the eye showing the better acuity and the eye showing the worse acuity. Stereopsis testing indicated that few, if any, of the infantile esotropes showed stereopsis at any of the test ages. Over 30% of the high hyperopes developed strabismus by age 3 years, but none of the infants in the moderate hyperopia or family history groups developed strabismus.