Histologic Processing of the Eye for Obtaining the Macular Region of the Retina of the Cynomolgus Monkey

Abstract

Microscopic evaluation of the macular region of the retina is essential in preclinical drug safety studies in cynomolgus monkeys. A number of therapeutic agents are suspected of causing damage to the macula in humans; therefore, the macular region of the retina should be evaluated in preclinical drug safety studies in monkeys. Histopathologic examination of the fovea may be required for preclinical drug safety evaluation of certain ocular drugs for human risk assessment. Using the inferior oblique muscle as a landmark, the macula including the fovea was obtained in 100% of 20 eye sections. It is easier to obtain just the macular region of the retina than the fovea in the section. Measurements for the inferior oblique muscle (point of insertion), fovea, macula, and the optic disc for 20 eyes of untreated cynomolgus monkeys were taken. In the cynomolgus monkey, the macula was 2.01 mm in diameter and the fovea was 0.53 mm in diameter. The distance from the center of the optic disc to the center of the fovea was 3.23 mm. In the fixed eyes, the point of insertion of the inferior oblique muscle to the sclera was 5.96 mm. (The J Histotechnol 31:113, 2008)Submitted January 7, 2008; accepted with revisions June 22, 2008