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E.L. Irving, M.L. Kisilak, K.M. Clements, M.C. W. Campbell; Refractive Error and Optical Image Quality in Three Strains of Albino Rats . Invest. Ophthalmol. Vis. Sci. 2005;46(13):4334.
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© ARVO (1962-2015); The Authors (2016-present)
Purpose: Albino rats are frequently used in cognitive behavioral studies and as disease models. Spontaneous hypertensive (SHR) and Wistar Kyoto (WKY) are used as models of attention deficit hyperactivity disorder (ADHD) and depression, respectively, while Sprague–Dawley (SD) serve as controls. Since most of the studies examine performance on cognitive tests that are visuo–spatial in nature, it is important to know the visual capabilities of these strains before strong claims can be made regarding the nature of their behavioural deficits. Methods: Refractive errors were measured by retinoscopy in 3 different strains of albino rats, SHR (N=7), WKY (N=8), and SD (N=4). All rats were male and born within one week of each other. They were 9 months of age at the time of testing. A Hartmann–Shack setup was designed to evaluate the optical quality of the eyes. Rearing conditions were identical for all three strains. Food and water were given ad libitum and rats were subject to 12h dark/12h light cycles. Results: Refractive error differences were found between the three strains of rats. However, the variability in refractive error is relatively small between animals within a strain as well as between eyes in a given animal regardless of strain. SD: OD 15.25D ± 1.181D, OS 14.875D ± 0.718D; WKY: OD 9.125D ± 0.666D, OS 10.375D ± 0.706D; SHR: OD 5.714D ± 0.522D, OS 5.286D ± 0.421D. Hartmann Shack images were degraded compared to previous images from pigmented (Long Evans) rats due to large amounts of scattered light. Design modifications improved the Hartmann Shack images. Conclusions: There are differences in the visual optics between different strains of albino rats and between albino and pigmented rats. Further evaluation of visual function should be considered before concrete conclusions are drawn with regards to cognitive functions between strains. The relatively low variability between animals in a given strain, and between eyes in a given animal suggests that there may be control over eye growth. Refractive error is different between strains and may well be genetically determined. These data show very clearly that caution should be exercised when attributing performance differences to behavioral deficits without reference to optical differences.
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