Effects of illuminance and observation clock hour on miotic response in rats

Abstract

Miosis has been evaluated with dedicated devices under non-physiological condition. In this study, versatile video camera was used to examine the effects of illuminance and observation clock hour on the miotic response. Miosis score (pupil/cornea diameter ratio) of SD rats at ≤5 lx was 2-3 times higher than that at 400 lx. Observation clock hour had no effect on miosis score. In a positive control group, miosis score was decreased dose-dependently at ≤5 lx, but not at 400 lx. These results suggest that illuminance for miosis evaluation should be optimized for the purpose of each experiment.