LENTICULAR CHANGES IN RAINBOW-TROUT FOLLOWING CHRONIC EXPOSURE TO UV-RADIATION

Rainbow trout (Onchorynchus mykiss) were exposed to broad band ultravi olet 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 WA and 1.050 x 1 0(2) J cm(-2) of UVB. Control fish were maintained under UVB-free and blue-free conditions. Quantitative and qualitative evaluation of the t eleost crystalline lenses involved photo slitlamp biomicroscopy, dark- field stereomicroscopy and automated scanning laser monitoring. More c ataractous changes including discrete anterior subcapsular and 'doughn ut' opacities, and peri-nuclear haze were recorded in the lenses of th e fish that received chronic UV exposure. However, no significant diff erences were found in focal lengths and scatter within the sensitivity of the instrumentation. These results support the hypothesis that chr onic exposure to ambient levels of ultraviolet radiation is cataractog enic.