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LS Kwok, MT Coroneo; The Contribution Of Off-axis Light To Edge Glare In Pseudophakic Dysphotopsia . Invest. Ophthalmol. Vis. Sci. 2002;43(13):441.
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Purpose:To quantify the role of peripheral light focusing due to off-axis light in the edge glare phenomenon associated with pseudophakic dysphotopsia. Methods:A model pseudophakic eye was constructed from the Kooijman wide-angle schematic eye combined with standard constants from the Holladay pseudophakic eye. Peripheral light focusing due to off-axis light incident on the temporal cornea was ray-traced in a model intraocular lens (IOL) of radius 7.2 mm, 6 mm dia, 0.72 mm centre thickness, and refractive index of 1.5597. Results:Light incident on the temporal cornea at oblique angles was able to strike the nasal portion of the IOL. The focusing was two or more times incident intensity. The critical incidence window at the temporal cornea was in the range 90 15 deg to the visual axis. The light focusing effect creates focused spots of light in the nasal edge region of the IOL. Conclusion:Off-axis light from the temporal cornea is able to form intense light spots in the nasal edge of the IOL. These spots constitute glare sources and may be of sufficient intensity to disturb vision. Our findings indicate that off-axis light may be an important contributor to some disability glare problems, and that IOL edge design should be re-evaluated to minimize dysphotopsia associated with peripheral focusing effects.
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