EFFECTS OF VIEWING DISTANCE ON EYE GROWTH & REFRACTIVE DEVELOPMENT

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This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. Myopia (nearsightedness) is a visual disorder that affects 25% of Americans, at a cost of $4 billion/year. Through animal models we have attempted to identify the nature of the environmental influence by an emphasis on the quality of the retinal image, using form deprivation or constant defocus. Our initial studies have tested test several corollaries of the following hypothesis: prolonged exposure to visual stimuli at a near viewing distance is sufficient to induce excessive ocular elongation and relative myopia in rhesus monkeys. Aim 1. To test the prediction that daily performance of a visual task at a near viewing distance (NVD) will induce a myopic shift. Aim 2. To test the hypothesis that the restriction of viewing distance to near is sufficient to induce a myopic shift during postnatal development. Measurements of refractive error were obtained via cycloplegic retinoscopy, measurements of axial length of the eye will be made via A-scan ultrasound, and measurements of accommodative behavior were made using infra-red (IR) photorefraction. After these functional relationships have been established, future studies will be conducted to examine neural mechanisms. Our goal is to understand the relationship between visual experience, eye growth, and refractive status, and the mechanisms that guide those relationships.