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S Lofgren, M Ayala, M Kakar, V Mody Jr, X Dong, P Soderberg; UVR Cataract After Regional In Vitro Lens Exposure . Invest. Ophthalmol. Vis. Sci. 2002;43(13):3577.
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Purpose:Epidemiological studies show a correlation between solar ultraviolet radiation, type B (UVR-B) and cortical cataract. Cortical cataract occurs more often in the infero-nasal quadrant. This study investigates the effect of regional in vitro UVR-B exposure on the rat lens. Methods:25 to 100% of the anterior surface of lenses from pigmented rats was exposed in vitro to UVR-B in a concentric manner. Also, a 25% quadrant area, including the equator, was exposed. Irradiance was 1.3 W/m2 and exposure time 30 minutes. Nonexposed contralateral lenses were used as controls. The UVR-B irradiance was same for all exposed lenses. The lenses were incubated one week in standard culture environment. The amount of cataract was quantified daily by measuring intensity of forward light scattering in the cultured lenses. Results: By day 2, the epithelium in exposed areas developed granular opacities. The borders between nonexposed and exposed areas were sharply demarcated. The epithelial changes were repaired and the damaged area decreased in size. Lenses with 100% surface area exposed developed severe cataract, including equatorial and posterior cortical cataract. The less prominent epithelial changes decreased but were not completely abolished. Lenses with 50% central area exposure exhibited peak light scattering at day 2-3 and were thereafter partially repaired. 25% central area exposure induced a lower peak of light scattering at day 2-3 and repair thereafter. Opacities after quadrant area exposure were repaired in the central zone but not at the equator. Conclusion:The lens equator is more sensitive to UVR than the anterior central zone. When the damaged area exceeds a critical size, repair capacity becomes limited.
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