Influence of a prolonged period of low-dosage x-rays on the optic and ultrastructural appearances of cataract of the human lens.

Abstract

Human lenses extracted for cataract 26 yr after long-term exposure to an imperfectly shielded Ra source were examined by slit-lamp photography, thin-section light microscopy and EM. Anterior epithelial cells were fibroblast-like, and germinal epithelium and vacuolated cortical fibers accumulated at the equator. A zone of light scatter at the anterior pole corresponded to an area of breakdown of cortical lens fibers, where unusual feathery fibers were orientated perpendicular to the lens surface. Two zones of light scatter separated by a 250 .mu.m clear interval were seen in the posterior cortex. The zone at the posterior pole corresponded to an area of fiber liquefaction and large rounded membrane whorls, while the deeper zone comprised small flattened membrane whorls. The characteristic plaques of swollen abnormal cells described in previous histological studies of X-ray cataract were not present. This and other differences probably reflect the extremely long time course and repeated subliminal doses to which the patient was exposed.