In vivo human crystalline lens topography

Custom high-resolution high-speed anterior segment spectral domain optical coherencetomography (OCT) was used to characterize three-dimensionally (3-D) the human crystalline lensin vivo. The system was provided with custom algorithms for denoising andsegmentation of the images, as well as for fan (scanning) and optical (refraction) distortioncorrection, to provide fully quantitative images of the anterior and posterior crystalline lenssurfaces. The method was tested on an artificial eye with known surfaces geometry and on ahuman lens in vitro, and demonstrated on three human lenses invivo. Not correcting for distortion overestimated the anterior lens radius by 25% andthe posterior lens radius by more than 65%. In vivo lens surfaces were fittedby biconicoids and Zernike polynomials after distortion correction. The anterior lens radii ofcurvature ranged from 10.27 to 14.14 mm, and the posterior lens radii of curvature ranged from6.12 to 7.54 mm. Surface asphericities ranged from −0.04 to −1.96. The lenssurfaces were well fitted by quadrics (with variation smaller than 2%, for 5-mm pupils), withlow amounts of high order terms. Surface lens astigmatism was significant, with the anteriorlens typically showing horizontal astigmatism (Z22 ranging from −11 to −1 µm) and the posteriorlens showing vertical astigmatism (Z22 ranging from 6 to 10 µm).OCIS codes: (110.4500) Optical coherence tomography, (120.6650) Surface measurements, figure, (120.4640) Optical instruments, (120.4800) Optical standards and testing, (110.6880) Three-dimensional image acquisition, (330.7327) Visual optics, ophthalmic instrumentation