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H. Zhao, A.J. Lang; Sources of Glare in Pseudophakic Eyes . Invest. Ophthalmol. Vis. Sci. 2005;46(13):4324.
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Identify the various sources of glare in pseudophakic eyes, ranking the relative retinal intensity and contrast.
We used a finite pseudophakic eye model: Liou and Brennan cornea, equal biconvex 20D monofocal IOL with square edge and 7.0 mm pupil. Non–sequential trace of 400x400 rays simulated glare rays from a distance headlight. The glare ray angles sampled are: 23o, 35o, 55o, 70o. An emmetropic observer eye was used in front of the above eye to monitor the Perkinje III and IV glare. Glare evaluation metrics used are: the average intensity (irradiance) and the Michelson contrast of the glare pattern on the retina.
In the observer’s eye, a circular disk pattern glare is found by rays from the IOL anterior surface (type A) and the IOL posterior surface (type B) for all glare angles. The patient observers have several types of glare: arc– or ring–like (curved towards the glare source image) by rays reflected from the IOL edge (type C); arc–like (curved away the glare source image) by rays transmitted through the IOL edge (type D); image–like by rays bypassed the IOL (type E); diffused disk–like by rays from multiple reflections from IOL and cornea surfaces (type F); diffused disk–like by rays back–scattered from the retina and reflected from IOL surfaces (type G). The table below lists the average intensity (A.I.) in arbitrary unit and the Michelson contrast (M.C.) of the different types of glare (Note type E below shows data only by rays reflected from IOL and cornea surfaces and then bypassed the IOL).
In the pseudophakic eye, glare types C and D are the most significant glare. Their average intensities are about 3 orders lower than the glare source image and their contrast is high. The type E to type G glare is about 2 orders lower than types C and D. In the observer’s eye, the average intensity of glare type A is extremely weak and glare type B is comparable to type F.
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