Strain differences in sensitivity to light-induced photoreceptor degeneration in albino mice

The sensitivity to light-induced photoreceptor degeneration was examined in 7 different inbred strains of albino mice. The mice were exposed to 3 weeks of constant fluorescent light at an illuminance level of 115-130 ft-c (ca. 1,265-1,430 lux), after which the eyes were examined histologically. The degree of light-induced photoreceptor degeneration was compared to that found in BALB/cByJ (BALB/c) albino mice, which have previously been described as sensitive to the damaging effects of light, and to C57BL/6J-c2J albino mice, which have been shown to be resistant to light-induced damage. Mice of the A/J, AKR/J and NZW/LacJ strains were indistinguishable from BALB/c mice in light sensitivity, as measured by mean outer nuclear layer thickness and the presence or absence of outer segment membranes. Mice of the Ma/MyJ and RF/J strains were somewhat more sensitive to light than BALB/c mice, and those of the RIIIs/J were far more sensitive than all of the other strains. The LG/J strain differed from other strains by individual mice displaying one of two degrees of light sensitivity, those similar to the light-sensitive Ma/MyJ and RF strains and those remarkably more resistant to light, with photoreceptor outer segment integrity even greater than that of the light-resistant C57BL/6J-c2J strain. These findings demonstrate that different inbred strains of a given species may exhibit a wide range of sensitivities to constant light exposure and that most albino mouse strains examined thus far are highly sensitive to the damaging effects of light.