Refractive index degeneration in older lenses: A potential functional correlate to structural changes that underlie cataract formation

Bahrami, Mehdi and Hoshino, Masato and Pierscionek, Barbara K. and Yagi, Naoto and Regini, Justyn and Uesugi, Kentaro (2015) Refractive index degeneration in older lenses: A potential functional correlate to structural changes that underlie cataract formation. Experimental Eye Research, 140. pp. 19-27. ISSN 1096-0007

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Official URL: https://doi.org/10.1016/j.exer.2015.08.011

Abstract

A major structure/function relationship in the eye lens is that between the constituent proteins, the crystallins and the optical property of refractive index. Structural breakdown that leads to cataract has been investigated in a number of studies; the concomitant changes in the optics, namely increases in light attenuation have also been well documented. Specific changes in the refractive index gradient that cause such attenuation, however, are not well studied because previous methods of measuring refractive index require transparent samples. The X-ray Talbot interferometric method using synchrotron radiation allows for measurement of fine changes in refractive index through lenses with opacities. The findings of this study on older human lenses show disruptions to the refractive index gradient and in the refractive index contours. These disruptions are linked to location in the lens and occur in polar regions, along or close to the equatorial plane or in lamellar-like formations. The disruptions that are seen in the polar regions manifest branching formations that alter with progression through the lens with some similarity to lens sutures. This study shows how the refractive index gradient, which is needed to maintain image quality of the eye, may be disturbed and that this can occur in a number of distinct ways. These findings offer insight into functional changes to a major optical parameter in older lenses. Further studies are needed to elicit how these may be related to structural degenerations reported in the literature.

Item Type: Journal Article
Keywords: Lens, Human, Cataract, Refractive index, Synchrotron, X-ray Talbot interferometry
Faculty: ARCHIVED Faculty of Health, Social Care & Education (until September 2018)
Depositing User: Lisa Blanshard
Date Deposited: 19 Feb 2021 16:43
Last Modified: 19 Feb 2021 16:43
URI: https://arro.anglia.ac.uk/id/eprint/706338

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