Effect of continued treatment with timolol maleate on corneal endothelium: A fluorophotometric study

Purpose. To verify whether the long-term use of timolol maleate is toxic for the corneal endothelium and whether the treatment time is a predisposing factor. Methods. We used fluorophotometry to study 40 eyes that had been treated with timolol maleate uninterruptedly during a prolonged time (from 6 months to 14 years). The results obtained were compared with a sample of 40 hypertensive eyes that had not received any treatment. Results. No statistically significant differences were found between the coefficient values of endothelial permeability between the treated and nontreated subjects. In addition, no differences were found in the coefficient of endothelial permeability between subjects treated with timolol in different treatment periods (between 6 and 12 months, between 1 and 5 years, and for >5 years). Conclusion. These results suggest that longterm treatment with timolol has little effect on the integrity of the corneal endothelium.