Objective To study the parameters of the anterior corneal surface in Chinese eyes based on the collection of raw elevation data of the surface using the ellipsoid fitting method. Methods Eighty eyes were included in this experimental study. The Levenbery-Marquardt method was used to fit the elevation data. The parameters of the anterior corneal surface were obtained by coordinate transformation and rotation processing. Spherical fitting， conic fitting and biconic fitting were also used to obtain the parameters of the anterior corneal surface for t test comparisons. Results The root mean square fitting error with ellipsoid fitting was as low as 2.14±0.56 μm for an 8 mm fitting diameter， and the standard deviation was only 0.56 μm， showing good reliability. However， the fitting error and fitting reliability for other fitting methods were inferior to ellipsoid fitting. For ellipsoid fitting， the radius of the anterior corneal surface was 7.67±0.23 mm， and the corresponding refractive power of the anterior corneal surface was 49.02±1.44 D. The Q-value of the anterior corneal surface was -0.33±0.09. The refractive power obtained with other fitting methods was higher than the refractive power obtained from the ellipsoid fitting （P<0.01） whereas the absolute obtained Q-value was lower than that obtained from the ellipsoid fitting （P<0.01）. Conclusion This study shows that the actual anterior corneal refractive power is higher than the widely accepted anterior corneal refractive power of 48 D and the anterior corneal surface is more prolate than expected.
刘永基,王肇圻,王雁. 基于椭球面拟合的人眼角膜前表面面型参数[J]. 中华眼视光学与视觉科学杂志, 2014, 16(6): 368-371.
Liu Yongji,Wang Zhaoqi,Wang Yan. Parameters of the anterior corneal surface based on ellipsoid fitting. Chinese Journal of Optometry Ophthalmology and Visual Science, 2014, 16(6): 368-371. DOI: 10.3760/cma.j.issn.1674-845X.2014.06.011
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