Long-term development of lens opacities after exposure to ultraviolet radiation at 300 nm.

The long-term development of lens opacities after short-term exposure to ultraviolet radiation (UVR) was determined. Altogether, 200 Sprague-Dawley rats received unilaterally 5 or 20 kJ/m2 UVR (lambda MAX = 300 nm, lambda 0.5 = 10 nm) in vivo, during 15 min. At 1, 4, 8, 16 and 32 weeks after exposure subgroups of 20 rats from each dose group were sacrificed. Both lenses were removed for measurement of intensity of forward scattered light. It was found that exposed lenses scatter light more than their contralaterals and that a higher dose induces more light scattering. After exposure to 5 kJ/m2, the mean difference in scattering remained unchanged between 1 and 32 weeks' latency, but the distribution of the individual differences in scattering became skew. For several animals, lens opacities induced by 5 kJ/m2 seemed to decrease during the observation period. Earlier observations in complement to current findings implicate that it is optimal to detect close-to-threshold UVR-induced cataract at 1 week after exposure.