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F. Manns, V. Fernandez, A. Ho, M. Hamaoui, S. Sandadi, J. Parel; Radius of Curvature, Asphericity and Spherical Aberration of the Crystalline Lens Surfaces In Situ in Eye-Bank Eyes . Invest. Ophthalmol. Vis. Sci. 2003;44(13):245.
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© ARVO (1962-2015); The Authors (2016-present)
Purpose: To measure the shape of the anterior and posterior surface of human cadaver lenses in situ using a corneal topography system and calculate the contribution of the lens surfaces to spherical aberration. Methods: Measurements were performed on 13 pairs of eyes using the PAR Corneal Topography System (PAR-CTS). To avoid deformation of the globe during dissection and measurements, a PMMA ring was bonded to the outer scleral shell. Anterior lens topography was measured after excision of the cornea and iris. Posterior lens topography was measured after sectioning the posterior segment and adherent vitreous. Throughout the experiments, the lens remained attached to the zonule-ciliary body framework with an intact annular scleral shell. The PAR-CTS files providing raw surface height were exported for analysis. In each surface, 18 meridians separated by 10 degrees were fitted using conic sections to obtain values of the apex radius of curvature (R) and shape factor (p). The contribution of the lens surfaces to primary spherical aberration was calculated using the formulas derived by Welford (Academic Press, 1974), which were applied to the Navarro eye model (J Optical Soc Amer, 1985). Results: The average radius of curvature and asphericity were R=10.15+/-1.39 mm and p=4.27+/-1.39 (oblate ellipse) for the anterior surface and R=-6.25+/-0.79 mm and p=-0.64+/-1.85 (hyperbole) for the posterior surface. A significant variation of the radius of curvature and shape factor as a function of the meridian angle (lens astigmatism) was found in some lenses. The calculated contribution of the average anterior and posterior lens surfaces to primary ocular spherical aberration was -1.630mm and -1.603 mm, respectively. Conclusions: Contrary to previously published findings, the anterior lens surface was found to steepen toward the periphery. On average, both lens surfaces were found to have a negative contribution to ocular spherical aberration. Supported in part by the Australian Cooperative Research Centre (CRC) Scheme, CRC for Eye Research and Technology, Sydney, Australia; NIH Grant EY14225; Florida Lions Eye Bank; Research to Prevent Blindness, NY, NY
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