Spontaneous Ocular Abnormalities in Sprague-Dawley Rats

We collected historical control data derived from pretreatment ophthalmologic examinations of young (4 to 7 wk of age) Sprague-Dawley (Crl:CD[SD]) male, (2033, 42 lots) and female (1322, 32 lots) rats used in toxicity studies at our facility from 2004 through 2015. Ophthalmologic examination of male and female rats by using a binocular indirect ophthalmoscope and slit lamp revealed high incidences of corneal opacity (61% and 60%, respectively), lenticular opacity (43% and 47%), persistent hyaloid artery (21% and 17%), and retinal folds (27% and 27%). All other ocular abnormalities of the globe, conjunctiva, cornea, anterior chamber, lens, iris, vitreous, and choroid or retina occurred at incidences of less than 5%. Corneal opacities were localized mainly in the corneal nasal (38% and 37%) and paracentral (32% and 33%) areas, and lenticular opacities predominantly occurred in the nuclear area (31% and 34%). We then compared the incidences of spontaneous ocular abnormalities between the first (2004 through 2009) and second (2010 through 2015) 6-y periods. Corneal opacity and persistent hyaloid artery in male and female rats occurred more frequently during the second 6-y than during the first (corneal opacity, second period: male, 68%; female, 66%; corneal opacity, first period: 49% and 51%; persistent artery, second period, 26% and 23%; persistent artery, first period; 12% and 10%). These results support the importance of updating historical control data regularly and providing useful information for toxicologists and ophthalmologists to differentiate treatment-related changes from spontaneous lesions.