Isolated human crystalline lens three-dimensional shape: A comparison between Indian and European populations

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There have been many studies on lens properties in specific populations (e.g. in China, Europe, Singapore, etc.) some of which suggest there may be differences between populations. Differences could be caused by ethnic or environmental influences or experimental procedures. The purpose of this study is to evaluate if any differences exist between Indian and European populations in the central geometric and full shape properties of human lenses. Two custom-developed spectral domain optical coherence tomography systems were used to acquire the crystalline lens geometry: one in India (69 lenses from 59 donors) and the other in Spain (24 lenses from 19 donors). The steps for obtaining accurate 3-D models from optical coherence tomography raw images comprised of image segmentation, fan and optical distortion correction, tilt removal and registration. The outcome variables were lens equatorial diameter, lens thickness, anterior and posterior lens thicknesses and their ratio, central radius of curvature of the anterior and posterior lens surfaces, lens volume and lens surface area. A mixed effects model by maximum likelihood estimation was used to evaluate the effect of age, population and their interaction (age*population) on lens parameters. After adjusting for age, there were no population differences observed in anterior and posterior radii of curvature, equatorial diameter, lens thickness, anterior and posterior lens thicknesses and their ratio, volume and surface area (all p ≥ 0.08). There was also no effect of the interaction term on anterior and posterior radii of curvature, equatorial diameter, lens thickness, anterior and posterior lens thicknesses and their ratio, volume and surface area (all p ≥ 0.06). All central geometric and full shape parameters appeared to be comparable between the European and Indian populations. This is the first study to compare geometric and full shape lens parameters between different populations in vitro.
This work was supported by the National Institutes of Health/National Eye Institute [Grants 2R01EY021834 and P30EY14801 (Center Grant)]; the Hyderabad Eye Research Foundation; Ministerio de Educacion y Ciencia, Spain (FIS2017- 84753-R), European Research Council (ERC-2018-AdG-833106) and IMCUSTOMEYE Ref. 779960 (H2020- ICT- 2017-1) to S. Marcos, and European Research Council (ERC) under European Union’s Horizon 2020 research and innovation programme H2020-MSCA COFUND-2015 FP-713694, MULTIPLY(AdC), CSIC ICoop Program, Florida Lions Eye Bank and the Beauty of Sight Foundation, an unrestricted grant from Research to Prevent Blindness to the Department of Ophthalmology, University of Miami and the Henri and Flore Lesieur Foundation (J-M. Parel).