Ocular Distortion Measurement and Relationship with Refractive Error

Abstract

The underlying drivers of refractive error development in the human eye remain open areas of research. Axial elongation, peripheral ametropia, neurotransmitters at the retinal surface and environmental stimuli are a few factors that have been studied to describe the onset and progression of refractive error development. However, the ametropia puzzle remains unsolved and the number of people afflicted by ametropia is growing. One possible driver for refractive error development is distortion in the retinal image. However, no systems are available to objectively measure ocular distortion. To enable the measurement of ocular distortion, a novel imaging system is created and tested in a sample population. Using a modified fundus camera, a target is projected onto the retinal surface and imaged to a detector. A distortion criterion for a rotationally non-symmetric optical system is used to analyze the resulting distortion pattern. A simulated population of one thousand different configurations, for a model eye spanning -20 to +9 D, is used to investigate ocular distortion prior to human trials. A small human trial cohort was imaged using the modified fundus camera and compared to the simulated data set. The repeatability of the distortion measurements and its relationship to refractive error is investigated.