Structure/function relationship between optics and biochemistry of the lens.

Abstract

The lens is an important element in the optical system of the eye. It has a gradient of refractive index for purposes of aberration control and in order to provide the ocular system with sufficient power. The lens also contains unique structural proteins. Although much work has been done to characterize the lens proteins, a structure/function relationship between these entities and the optics of the normal lens had not been previously considered. To investigate if such a relationship exists, biochemical and optical investigations were carried out under the common theme of development and aging. Investigations of distribution patterns of the three protein classes and measurements of the refractive index gradient were made on bovine and human lenses over wide age ranges. The results of these studies were compared. Although there was no direct evidence of a link between a single protein class and the index gradient, there are hints from interspecies comparison, that the level of LMW proteins may determine the magnitude of the refractive index. It is also possible that the insoluble fraction, which bears the greatest relationship in trend to the refractive index gradient, may represent proteins (largely pounds-crystallins) which have been structurally altered in situ in order for the lens to maintain viable optical function under the conditions of continual growth and aging.