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.
Amblyopia, or ?lazy eye? is decreased vision in one eye that affects 3% of children, most often as a result of binocularly discordant visual experience from strabismus (crossed eyes) or anisometropia (blurred vision in one eye). While patching the stronger eye often results in some visual improvement, patching treatment ignores the binocular discordance that gives rise to amblyopia, and many children develop recurrent and residual amblyopia. Our long-term goal is to broaden our understanding of amblyopia to facilitate the design of therapies that will reduce or eliminate residual and recurrent amblyopia. The objectives of this grant are to develop and assess a new methodology that enables early accurate identification of amblyopia, evaluate binocular treatment that may provide more complete and stable vision rehabilitation, and delineate the effects of amblyopia and amblyopia treatment on everyday tasks.
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