The presence and significance of hyperopic defocus across the retina in young myopic eyes

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Project Summary: Myopia research is time-critical due to the surge its worldwide prevalence and severity. Knowledge of the mechanisms controlling normal eye growth and contributing to myopia development will provide improved chances of effective treatment. My long-term goal is to become a leading scholar and scientist examining the core mechanisms and treatment strategies to cope with the current world-wide epidemic of myopia. The key hypothesis is that ocular growth and myopia development are regulated by visual feedback associated with specific characteristics of the eye's retinal image. Accordingly, I am proposing to answer three questions: (1) Is defocus sign an available cue in the peripheral retina? (2) How much hyperopic defocus do children experience when viewing at near? (3) Does peripheral hyperopia exist in children engaged in near viewing? To answer these crucial questions, I have developed a group of 4 mentors (Prof. Bradley for Visual Impact of Ocular Optics; Dr. Wildsoet for myopia development; Dr. Yu for three dimensional visual tracking; Dr. Candy for vision and oculomotor behavior in children) and two experienced collaborators (Prof. Thibos for peripheral vision and off-axis optics, and Dr. Kollbaum for multifocal CL fitting in children). Projects: (1) Assess the discriminability of complex natural scenes with different amounts of computationally generated + and - defocus from eye models with controlled levels of defocus-induced amplitude and phase changes. We hypothesize that untrained children cannot identify the sign of defocus for typical polychromatic complex natural scenes outside of the fovea or near foveal retina. (2) Monitor the real-time viewing distance and binocular accommodation behavior when children are involved in near work with and without myopia treatment. We hypothesize that when performing the same near task, the myopic children systematically adopt shorter working distances and experience larger accommodative lags (hyperopic defocus) than emmetropic eyes. Working distance may also be affected by myopia control treatments, which will affect their ability to remove hyperopic defocus. (3) Monitor the hyperopic defocus across the visual field. Coupled with peripheral target distance captured with the head-mounted tracking system and VisionApp, we will use wide-field aberrometry to monitor the presence of any hyperopic and myopic image planes, and evaluate image characteristics during accommodation with natural and small pupils. We hypothesize that pupil miosis can improve foveal and peripheral image quality in developing myopia and attenuate any hyperopic defocus cue. In sum, these studies of the optical realities and neural characteristics experienced by developing and treated myopes will provide useful insights to better understand this myopia epidemic and provide our best chance of myopia prevention.