Abstract
Abstract: :
Purpose: Subnormal stereopsis is a major feature of infantile esotropia. The purpose of this study was to determine how the duration of strabismus effects stereopsis development. Methods: Infant macaques were fitted with goggles on day 1 of life to induce optical strabismus of 11.4–22.8 deg. The Short Duration group (2 experimental and 1 control) wore the goggles for a period of 3 wks (the equivalent of 3 months in humans). The Long Duration group (2 experimental and 1 control) wore the goggles for a period of 3–6 months (the equivalent of 12–24 months in humans). At age 1 year, eye movement recording during a forced–choice preferential looking task was used to assess random dot stereopsis. Results: Control monkeys achieved a correct response rate > 80% for disparities of .01 – 5 degs. Equivalent thresholds of stereopsis were found in Short Duration monkeys, who also regained fusional vergence. Long Duration monkeys were stereoblind, insensitive to disparities as large as ± 5 deg (18 x 103 arc sec). Long Duration monkeys also lacked a fusional vergence response and displayed the other ocular motor deficits that typify infantile esotropia. Conclusion: Primates can repair maldevelopments of stereopsis and fusional vergence so long as the duration of misalignment does not exceed the equivalent of 3 mos in humans.
Keywords: binocular vision/stereopsis • strabismus • strabismus: treatment