Comparative Evaluation of Mydriatic and Miotic Responses of Atropine and Pilocarpine on Rabbit Eye: An Experimental Study

Abstract

This study was conducted to evaluate and compare the pharmacological effects of atropine and pilocarpine on pupillary diameter and intraocular pressure using a rabbit eye model. Healthy New Zealand White rabbits were used, and the drugs were administered topically, with the contralateral eye serving as a control. Pupillary diameter, intraocular pressure, and anterior chamber changes were recorded at predetermined time intervals. Pilocarpine (2%) produced rapid and significant miosis, with maximum constriction observed within 30 minutes, followed by gradual recovery. It also caused a notable reduction in intraocular pressure, indicating enhanced aqueous humour outflow. In contrast, atropine (1%) induced marked and sustained mydriasis, with peak dilation observed at 30–60 minutes and prolonged effects throughout the study period. A slight increase in intraocular pressure was noted with atropine. Slit-lamp examination revealed mild aqueous flare in pilocarpine-treated eyes, while atropine-treated eyes showed no significant changes. The findings demonstrate the opposing pharmacological actions of parasympathomimetic and parasympatholytic agents on ocular physiology. This study highlights the usefulness of the rabbit eye model in evaluating ocular drug responses and reinforces the clinical relevance of these agents in ophthalmic practice.