The cost of myopia to society is enormous. Research studies on myopia, with an emphasis on identifying the risk factors for myopia development among young adults and school-children, are needed to improve health care in vision. The long-term objective of the proposed research is to understand the role of sustained use of the eyes at near in the etiology of environmental induced myopia. In this proposed study we are going to focus on the role of peripheral vision in the development of myopia. The objectives of this study are: (1) to determine whether peripheral vision affects accommodation and whether the effects are different between emmetropic and myopic subjects; (2) to compare the difference in the thickness of the retina between emmetropic and myopic eyes and determine whether a period of near-work can temporally change the thickness of the retina. Two experiments are designed to answer these questions. In the first experiment, we will compare the subject's dark-focus and the accommodative response to a distant target before and after a period of near-work and compare the difference in these results between emmetropic and myopic subjects. In the second experiment, we will measure the retinal thickness using optical coherence tomography (OCT) and compare the difference in the thickness of the retina before and after a period of near-work and the difference in the measured results between emmetropic and myopic subjects. Repeated-measures ANOVA will be used for data analysis. The results of this study will provide a better understanding of the etiologies of human refractive errors in young-adults and school children. This understanding has potential for the development of new treatment and prevention strategies for myopia.