Lenticular changes in rainbow trout following chronic exposure to UV radiation.

Rainbow trout (Onchorynchus mykiss) were exposed to broad band ultraviolet irradiation for a period of 205 days with a 12h/12h on/off cycle. Total radiant exposure was 8.279 x 10(3) J cm-2 of UVA and 1.050 x 10(2) J cm-2 of UVB. Control fish were maintained under UVB-free and blue-free conditions. Quantitative and qualitative evaluation of the teleost crystalline lenses involved photo slitlamp biomicroscopy, dark-field stereomicroscopy and automated scanning laser monitoring. More cataractous changes including discrete anterior subcapsular and 'doughnut' opacities, and peri-nuclear haze were recorded in the lenses of the fish that received chronic UV exposure. However, no significant differences were found in focal lengths and scatter within the sensitivity of the instrumentation. These results support the hypothesis that chronic exposure to ambient levels of ultraviolet radiation is cataractogenic.