Spontaneous ophthalmic lesions in young Sprague-Dawley rats.

Eight hundred eight Sprague-Dawley rats were examined for ophthalmic abnormalities during a pretest period in various preclinical safety assessment studies. Persistent pupillary membrane, corneal crystal, healed minor trauma, synechia, coloboma of the iris, lens luxation, cataract, persistent hyperplastic primary vitreous, vitreous hemorrhage, coloboma of the optic disc or choroid, remnant of hyaloid arterial system, retinal hemorrhage, retinal detachment, retinal folding and choroidal defect were observed. The incidences of corneal crystal, synechia, and nuclear cataract in this survey were higher than those reported previously. On the other hand, retinal folding in this survey was less common than that reported previously. These results suggest that background data of eye problems in albino rats should be accumulated in each own laboratory colony. In addition, since spontaneous eye problems are common in young albino rats, elimination of rats with ophthalmic abnormalities from study groups by an ophthalmic examination during a pretest period would facilitate to evaluate toxicity potential of test compounds in safety assessment studies.