Relative Toxicity of Three Corneal Anesthetics Measured in Vitro with the Cultured Bovine Lens

Abstract

The relative ocular toxicity (damage and recovery) of three corneal anesthetics was determined by measuring changes in focal length variability (i.e., sharpness of focus) in the cultured bovine lens. The optical quality of cultured lenses was measured using a scanning laser system consisting of a low-power scanning helium-neon laser, video cameras, and a video-frame digitizer. Lenses were exposed to three common corneal anesthetics: Fluress, Fluoracaine, and Alcaine. The results indicate that lenses treated with Alcaine surpassed a 100% increase in focal length variability (FLV) in the least amount of time, but did demonstrate recovery. Lenses treated with Fluoracaine showed a 100% increase in FLV after Alcaine, but recovered more slowly. The Fluress-treated lenses did not experience a 100% increase in FLV and did not differ significantly (p<0.05) from the controls at any point in the 48 h study. The results indicate that Fluress exhibits the lowest level of ocular toxicity compared to Alcaine and Fluoracaine. The data also show that measuring focal length variability with a scanning laser system is a useful and objective test to determine the toxicity and potential irritancy of ocular agents.