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Hierarchical Structure and Light Scattering in the Cornea

Published online by Cambridge University Press:  21 February 2011

R. A. Farrell
Affiliation:
Milton S. Eisenhower Research Center The Johns Hopkins University Applied Physics Laboratory Johns Hopkins Road, Laurel, MD 20723
D. E. Freund
Affiliation:
Milton S. Eisenhower Research Center The Johns Hopkins University Applied Physics Laboratory Johns Hopkins Road, Laurel, MD 20723
R. L. McCally
Affiliation:
Milton S. Eisenhower Research Center The Johns Hopkins University Applied Physics Laboratory Johns Hopkins Road, Laurel, MD 20723
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Abstract

The complex hierarchical structure of the cornea of the eye as it is known from light and electron-microscopy is reviewed. Microscopy depicts the cornea as a layered structure with each layer parallel to the cornea's surfaces. The middle 90% of the cornea is a connective tissue layer called the stroma, which in turn is comprised of 2 μm thick sheets (lamellae) of collagen fibrils embedded in a ground substance. Fibrils within a given lamella have their axes parallel to one another, while fibril axes in adjacent lamellae make large angles with one another. Predictions of light scattering theory are then used to show how light scattering measurements made on fresh tissue can test these structures for possible artifacts due to preparative procedures. With unpolarized light, the total scattering cross-section depends on the fibrillar ultrastructure, but not on the lamellar structure. Angular scattering depends on both levels of hierarchical organization. The lamellar level of organization is especially significant for the propagation and scattering of polarized light. To date the structural implications of scattering measurements are in accord with structures seen in electron micrographs.

Type
Research Article
Copyright
Copyright © Materials Research Society 1992

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