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Published September 2006 | Published
Journal Article Open

simEye: computer-based simulation of visual perception under various eye defects using Zernike polynomials

Abstract

We describe a computer eye model that allows for aspheric surfaces and a three-dimensional computer-based ray-tracing technique to simulate optical properties of the human eye and visual perception under various eye defects. Eye surfaces, such as the cornea, eye lens, and retina, are modeled or approximated by a set of Zernike polynomials that are fitted to input data for the respective surfaces. A ray-tracing procedure propagates light rays using Snell's law of refraction from an input object (e.g., digital image) through the eye under investigation (i.e., eye with defects to be modeled) to form a retinal image that is upside down and left-right inverted. To obtain a first-order realistic visual perception without having to model or simulate the retina and the visual cortex, this retinal image is then back-propagated through an emmetropic eye (e.g., Gullstrand exact schematic eye model with no additional eye defects) to an output screen of the same dimensions and at the same distance from the eye as the input object. Visual perception under instances of emmetropia, regular astigmatism, irregular astigmatism, and (central symmetric) keratoconus is simulated and depicted. In addition to still images, the computer ray-tracing tool presented here (simEye) permits the production of animated movies. These developments may have scientific and educational value. This tool may facilitate the education and training of both the public, for example, patients before undergoing eye surgery, and those in the medical field, such as students and professionals. Moreover, simEye may be used as a scientific research tool to investigate optical lens systems in general and the visual perception under a variety of eye conditions and surgical procedures such as cataract surgery and laser assisted in situ keratomileusis (LASIK) in particular.

Additional Information

© 2006 Society of Photo-Optical Instrumentation Engineers. Paper 05396R received Dec. 30, 2005; revised manuscript received Jun. 9, 2006; accepted for publication Jun. 14, 2006; published online Oct. 24, 2006. The authors would like to thank Vincent McKoy for a critical review of the manuscript and Wayne Waller for invaluable discussions about the complexity and concept of visual perception. One of the authors (WF) would like to thank Erich W. Schmid for having introduced him to the field of ray tracing in ophthalmology. One of the authors (DM) would like to acknowledge the support of the Summer Undergraduate Research Fellowship (SURF) program at Caltech. This research and the fellowship were supported by National Science Foundation Grant No. EEC-0310723.

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August 22, 2023
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