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R. Urs, A. Ho, F. Manns, J.-M. Parel; Fourier Model of the Whole Profile of the Isolated Human Crystalline Lens. Invest. Ophthalmol. Vis. Sci. 2009;50(13):6131.
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To develop a single function that models the shape of the whole isolated ex-vivo human crystalline lens shape as a function of age.
Shadow-photogrammetric images of 28 whole isolated human lenses (PMT=1 to 5 days) ranging in age from 6 to 90 years were recorded. Lens contours were extracted using MATLAB’s morphological and edge detection functions. The position of the lens center and the tilt angle of the lens were calculated by fitting the contour to a 10th-order even Fourier series containing tilt and decentration terms in a polar coordinate system using MATLAB’s curve fitting toolbox. The Fourier series did not include phase terms to ensure axis-symmetry in the resultant model. This preliminary analysis was used to correct for tilt and decentration. The corrected profiles were resampled and the first 11 coefficients of the Fourier decomposition were calculated and analyzed as a function of age.
The root mean squared error between the original lens contour and the lens profile reconstructed using the coefficients of the Fourier decomposition ranged from 15 to 108 µm. Only the coefficient of the zeroth-order term (i.e. diameter of the ‘equivalent’ fitted circle) showed a significant increasing trend with age (a0 = 0.00787 x Age + 2.67458; p<0.0001).
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