Randomised prospective masked study comparing patient comfort following the instillation of topical proxymetacaine and amethocaine

Abstract

Aims - To evaluate the claim that topical proxymetacaine produces little or no discomfort on instillation by comparing it against topical amethocaine. Methods - This randomised, masked, double blind, prospective study involved 53 consecutive patients. Each patient received one drop of amethocaine 0.5% in one eye and one drop of proxymetacaine 0.5% in the other. The duration of the stinging sensation and degree of discomfort (using descriptive and a linear analogue method) for each topical anaesthetic was assessed. Results - The mean duration of stinging was 3.2 seconds for proxymetacaine and 22.1 seconds for amethocaine the difference being statistical significant (p < 0.001). The mean descriptive discomfort score was 2.6 for proxymetacaine and 14.2 for amethocaine (p = 0.01). The mean linear analogue score was 5.8 for proxymetacaine and 35.6 for amethocaine (p < 0.001). Proxymetacaine had a successful tonometry rate of 93% and amethocaine 98%. Conclusion - This clinical study confirms that proxymetacaine is more comfortable on instillation than amethocaine. Minimising unnecessary patient discomfort is not only ideal, but encourages cooperation in apprehensive patients especially in children.