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. While there is a significant positive correlation between the amounts of time a person engages in nearwork tasks (e.g. reading) and the incidence of myopia, there is no direct evidence of a causal association, and the nature of this relationship has remained a mystery for over a century (ethical considerations preclude the use of human subjects to address this question directly through empirical research). The present project was undertaken to determine whether prolonged performance of nearwork tasks could lead to the development of myopia. The objectives were to identify an appropriate task and behavioral setup and to ensure that optical performance was appropriate. This project yielded some exciting results, which are being used as the basis for a recently submitted NIH grant application. Briefly, prior to the onset of training on the behavioral task, adolescent rhesus monkeys exhibited a stable refractive error of a few degrees of hyperopia, which is the norm for this species. In daily sessions monkeys worked for food reinforcement on a visual discrimination task displayed on a computer located within arm¿s reach (at near). Over time, all 3 subjects have undergone a myopic shift in refractive error, exhibiting zero or nearly zero refractive error. These data may provide the first direct evidence that prolonged performance of a nearwork task is associated with the development of myopia. Recently, we have verified that during the performance of the task, the monkeys are focused on the computer screen, which confirms that the optical/visual demands of the task are similar to those of reading (i.e. focused at near). This monkey model will allow us to determine what aspects of the visual task contribute to the effects of refractive development and the development of myopia and will prove useful in clinical efforts to prevent myopia or reduce its progression.