Evolution of Ultraviolet Radiation–B (UVR–B)–Induced Cataract in the Pigmented Guinea Pig

Abstract

Abstract: : Purpose: To investigate the short–term development of cataracts after acute exposure to ultraviolet radiation–B (UVR–B) in the pigmented guinea pig. Methods: Twenty–four female pigmented guinea pigs, five to eight weeks of age, were exposed unilaterally to 80 kJ/m² UVR–B under anesthesia in vivo for sixty minutes. The guinea pigs were euthanized after post–exposure intervals of 1, 2, 4, or 8 days. Each lens was extracted and photographed. The development of forward light scattering for the lens was used to quantify the amount of cataract as expressed in transformed equivalent diazepam concentration units (tEDC). Results: Non–exposed corneas remained clear, while exposed corneas developed photokeratitis. All non–exposed lenses were devoid of cataract. All exposed lenses developed anterior subcapsular opacities at 1 day after UVR–B exposure. The surface area of the opacities decreased from 2 days to 8 days after exposure. Exposed lenses scattered more light than the corresponding contralateral lenses for the animals of the four groups. The mean differences ± 95% confidence intervals in forward light scattering between the exposed and non–exposed lenses for each group in tEDC were: 0.052 ± 0.036 [1 day]; 0.034 ± 0.018 [2 days]; 0.041 ± 0.024 [4 days]; and 0.044 ± 0.018 [8 days]. A maximum amount of forward light scattering in the exposed lens developed at one day post–UVR–B–exposure and was still present up to eight days after exposure. Conclusions: Anterior subcapsular cataract develops one day after exposure to UVR–B in the pigmented guinea pig. Maximum intensity of forward light scattering develops one day after exposure to UVR–B and remains constant up to eight days after exposure. One day is an appropriate time interval for study of UVR–B safety limit in the pigmented guinea pig.

Keywords: radiation damage: light/UV • cataract • cell death/apoptosis