Binocular Vision, Amblyopia, and Refractive Development

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Project Summary/Abstract Amblyopia is a neurodevelopmental vision disorder that affects 3% of children. It results from discordant visual experience during childhood, most often from strabismus or anisometropia. Strabismic and anisometropic amblyopia impair the visual acuity and contrast sensitivity of one eye. Typically, disrupted binocular vision (reduced or nil stereoacuity and interocular suppression), and ocular motor abnormalities are also present. These deficits are associated with reduced fine motor skills and reading speed even during binocular viewing. In turn, these associated deficits may affect academic success and self-esteem in children. During the current project period, we identified an association between abnormal binocular vision and fixation instability, discovered that interocular suppression precedes the onset of amblyopia, that the severity of suppression is correlated with the depth of amblyopia, that suppression is reduced with binocular amblyopia treatment, and investigated new binocular amblyopia treatments designed to reduce suppression and improve visual acuity. While our binocular treatment led to sustained improvement in visual acuity, these early studies were limited in 4 respects: 1) the treatment protocols were designed for short-term treatment trials, lasting <4 weeks so the maximum improvement with binocular treatment is unknown, 2) none of the treatment protocols were specifically designed to improve stereoacuity, 3) visual acuity was the primary outcome measure in all of the studies, so we know little about the relative effectiveness of patching versus binocular treatment in rehabilitating fine motor kills, reading speed, and self-esteem, and 4) the treatments have only been applied to amblyopic children age 4 years and older. Our collaborative research group is now poised to address these critical issues. In Aim 1, we will evaluate the effectiveness of enhanced binocular amblyopia treatments in achieving a more complete and stable recovery. In Aim 2, we will evaluate the effects of successful amblyopia treatment (patching or binocular treatment) on fine motor skills, reading speed, and self-perception. In Aim 3, we will evaluate a novel visual acuity measurement for <3-year-old children using a device that induces and measures reflexive eye movements (OKN) to moving fields of vanishing optotypes. Upon conclusion, our investigation of enhanced binocular treatment protocols and the effects of amblyopia treatment on the performance of everyday tasks will inform the design of new, more effective amblyopia treatments and the adoption of new outcome measures (reading, fine motor skills, and self-esteem) for clinical trials. In addition, we will have an accurate method to diagnose and monitor amblyopia in 1- to 3-year old children that will allow us to conduct future amblyopia treatment trials in this age range.