Age-dependent variation of the gradient index profile in human crystalline lenses

Alberto De Castro, Damian Siedlecki, David Borja, Stephen Uhlhorn, Jean-Marie A Parel, Fabrice Manns, Susana Marcos

Research output: Contribution to journalArticle

27 Scopus citations

Abstract

An investigation was carried out with the aim of reconstructing the gradient index (GRIN) profile of human crystalline lenses ex-vivo using optical coherence tomography (OCT) imaging with an optimization technique and to study the dependence of the GRIN profile with age. Cross-sectional images of nine isolated human crystalline lenses with ages ranging from 6 to 72 (post-mortem time 1 to 4 days) were obtained using a custom-made OCT system. Lenses were extracted from whole cadaver globes and placed in a measurement chamber filled with preservation medium (DMEM). Lenses were imaged with the anterior surface up and then flipped over and imaged again, to obtain posterior lens surface profiles both undistorted and distorted by the refraction through the anterior crystalline lens and GRIN. The GRIN distribution of the lens was described with three variables by means of power function, with variables being the nucleus and surface index, and a power coefficient that describes the decay of the refractive index from the nucleus to the surface. An optimization method was used to search for the parameters that produced the best match of the distorted posterior surface. The distorted surface was simulated with accuracy around the resolution of the OCT system (under 15m). The reconstructed refractive index values ranged from 1.356 to 1.388 for the surface, and from 1.396 to 1.434 for the nucleus. The power coefficient ranged between 3 and 18. The power coefficient increased significantly with age, at a rate of 0.24 per year. Optical coherence tomography allowed optical, non-invasive measurement of the 2D gradient index profile of the isolated human crystalline lens ex vivo. The age-dependent variation of the changes is consistent with previous data using magnetic resonance imaging, and the progressive formation of a refractive index plateau.

Original languageEnglish
Pages (from-to)1781-1787
Number of pages7
JournalJournal of Modern Optics
Volume58
Issue number19-20
DOIs
StatePublished - Nov 10 2011

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Keywords

  • crystalline lens
  • gradient index
  • OCT

ASJC Scopus subject areas

  • Atomic and Molecular Physics, and Optics

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