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Yifei Wu, T. Rowan Candy; A two-dimensional model simulating the pupil image in eccentric photorefraction. Journal of Vision 2017;17(7):54. doi: 10.1167/17.7.54.
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© ARVO (1962-2015); The Authors (2016-present)
Eccentric photorefraction and Purkinje image analyses of video can be used to estimate refractive state and eye position simultaneously (Schaeffel, Wilhelm, & Zrenner, 1993). They are used in screening and visual development studies (Choi et al., 2000). They are also helpful in understanding atypical development, but little is known about the effect of a number of variables (e.g. the impact of spectacle power and vertex distance). A two-dimensional model was built in Zemax to simulate eccentric photorefraction using sequential ray tracing. The two sub-models were: a forward version with appropriate light sources to create the retinal image and a backward version to create the camera image using the retinal image as the source (Chen, Tan, & Lewis, 2003). The slope of the luminance distribution across the pupil image was plotted against refractive state (±15D) and trial lens power (±8D) for a number of conditions. As shown previously (Roorda, Campbell, & Bobier, 1997), the results demonstrated slope saturation for significant refractive errors (>+4 & <−6D) and significant effects of pupil size. Refractive correction resulted in slope changes of up to 40% due to image magnification effects.
Meeting abstract presented at the 2016 OSA Fall Vision Meeting
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