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D. T. Moore, Y. Huang; Human Eye Modeling Using a Single Equation of Gradient Index Crystalline Lens for Relaxed and Accommodated States. Invest. Ophthalmol. Vis. Sci. 2007;48(13):982.
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© ARVO (1962-2015); The Authors (2016-present)
Though different human eye models have been constructed for studying its optical properties, there is not a model that simulates its accommodation process. We have built a dynamic eye model that includes a gradient index (GRIN) crystalline lens to simulate various accommodation states.
Different from the existing eye models that inserted a dummy surface inside the crystalline lens and used two separate equations to define its GRIN profile, we used one single equation to describe its entire GRIN distribution. By coupling the GRIN equation to the lens thickness, we created a dynamic lens model whose GRIN profile changed with its shape. Linear deformation was applied, but the expansion coefficients for lens nucleus and cortex were chosen differently to mimic the fact that lens nucleus is the active element in lens shape change during accommodation.
Both relaxed state and 10 diopter accommodated eye were simulated in lens design software CODE V. The relaxed state eye matched well with its template model-the Liou-Brenna Eye. The 10 diopter eye showed that it acquired adequate optical power by increased surface curvature as well as altered GRIN profile. Due to lack of accurate measurement data on the lens surface profile, the lens surface data were optimized by the software in order to maintain image quality after accommodation.
Our single equation crystalline lens GRIN representation has proven to be capable of reproducing the lens GRIN distribution accurately. With this lens model, we are able to simulate an accommodating eye with varying optical power. This model can be useful in understanding the crystalline lens behavior during accommodation, and it can serve as an eye model for contact lens design and future accommodating IOL design. Support from:NIH Grant BRP-EY014375, DARPA Grant of "Study of Wide Field of View Optical System Based on Animal Eyes"
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