Purpose:
To determine the extent of blue light exposure required to cause a 50-60% reduction in retinal function in different strains of pigmented and albino rat. The rodent blue light damage model is used to quickly screen therapeutic agents for the treatment of retinal degeneration and geographic atrophy related to AMD. A variety of rodent strains are used to evaluate pharmacokinetic, toxicology and complimentary efficacy data of potential treatments among different laboratories. In order to maximize the use of historical data to determine dosing and reduce the need for repeated experiments it is necessary to evaluate and validate the susceptibility of various rodent strains to blue light induced damage.
Methods:
Male Sprague Dawley (albino) and Brown Norway (pigmented) rats were allowed to acclimate in cyclic 12/12 white light for 3 weeks prior to light exposure. Following 12 hours of dark adaption, animals (N>6 per group) were exposed to 19 k-lux of fluorescent blue light for 12 to 2 hours. Control animals received no additional light exposure. Structural changes following light damage were measured with OCT, ERGs were recorded to assess retinal function and epresentative eyes were collected for histological evaluation.
Results:
Sprague Dawley rats required 8 hours of light exposure to reduce the a-wave and b-wave by 50% and 60% respectively. In contrast only two hours of blue light damage was necessary to similarly reduce the a- and b-wave of the Brown Norway Rat . ONL and OS thinning observed with OCT and histology was comparably reduced.
Conclusions:
Dramatic variations exist in blue light damage susceptibility among rat strains and a comprehensive validation of commonly used strains is required prior to treatment evaluation.
Keywords: degenerations/dystrophies • electroretinography: non-clinical • imaging/image analysis: non-clinical