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X. Wei, L. Thibos; Customization of a Wide Angle Schematic Eye by Ocular Wavefront Tomography. Invest. Ophthalmol. Vis. Sci. 2009;50(13):6163.
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Ocular wavefront tomography (OWT) is the process of using wavefront aberration maps obtained along multiple lines-of-sight (LoS) to determine the shape and position of the major refracting elements of an eye. One goal of OWT is to create a customized schematic model eye that is anatomically similar and functionally equivalent to the individual eye over a large field of view.
By taking account of the elliptical shape of the pupil, a Hartmann-Shack (HS) wavefront sensor can measure the off-axis wavefront aberrations of the human eye along multiple LoS over a wide field of view. With these measurements, plus biometric information of gross ocular anatomy, a merit function was formulated to numerically measure the goodness of the dual design goals of functional equivalence and anatomical similarity. To meet these dual goals, a generic, multi-surface model eye is optimized to achieve the global minimum of the merit function.
The OWT method was evaluated with three test cases: (1) a physical model eye with a doublet lens measured with a HS wavefront sensor along six LoS between -31 deg and +29 deg eccentricities, (2) a myopic GRIN model eye for which wavefront aberrations were computed by ray tracing, and (3) a human eye measured with HS wavefront sensor along eleven LoS between -25 deg and +25 deg. In all three test cases, the OWT optimized models are not only anatomically similar but also functionally equivalent to the test cases over a large field of view. The maximum discrepancies between aberrations of the OWT optimized models and the expectations were 0.05, 0.2, and 0.3 microns RMS for test case 1, 2, and 3 respectively along all the specified LoS.
Our implementation of OWT is a valid, feasible, and robust method for customizing an optical model to make it anatomically and functionally similar to individual eyes over a wide field of view.
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