A comparative study of the ocular tolerance of timolol-based preparation: the influence of preservatives on ocular tolerance

Purpose: Ophthalmic preparations can cause toxic ocular reactions, often as sociated with the use of preservatives. The aim of this study was to compar e the ocular tolerance of three ophthalmic preparations based on timolol: a preservative free ophthalmic preparation (Timabak(R)) and two other commer cially available preserved preparations (Timoptol(R) and Timoptol(R)LP). Methods: The effect of repeatedly instilling eye drops for 28 days on rabbi t eyes was assessed in vivo by mean of a confocal laser scanning ophthalmos cope. The corneal microlesions were selectively marked by fluorescein. Results and conclusion: The overall results show the good ocular tolerance of the three tested products. However, a closer comparison between the prod ucts brought out differences in the extent of lesions among the tested prod ucts depending on their composition. Indeed the preservative free eye drops appeared better tolerated than the two preserved preparations.