To evaluate the ocular surface inflammatory response to the presence of preservatives in nonselective beta-blocker eyedrops. Prospective, crossover, single-masked, randomized clinical study. study population: Twenty primary open-angle glaucoma or ocular hypertensive patients were divided in two groups, one treated with preservative-free timolol 0.5% (group 1) and the other with preserved timolol 0.5% (group 2) eyedrops. After 60 days of therapy and 3 more weeks of washout, the two groups switched to the other therapy. procedure: At each visit, basal tear samples were collected from the inferior conjunctival fornix for the determination of interleukin (IL)-1β tear concentrations by an enzyme-linked immunosorbent assay. Intraocular pressure measurement, conjunctival hyperemia, superficial punctate keratitis, and tear film breakup time were evaluated. main outcome measure: IL-1β concentration in tears following the use of preserved eyedrops. IL-1β tear concentrations increased significantly in both groups, compared with baseline values, during preserved timolol therapy. There were no statistically significant changes in hyperemia and superficial punctate keratitis throughout the study in either group. A statistically significant breakup time reduction was observed in both groups after 30 days and after 60 days of preserved therapy. The use of preservatives in timolol 0.5% eyedrops leads to tear film instability and ocular surface inflammatory changes documented by a reduction of breakup time and an increase of IL-1β tear concentrations. Preservative-free beta-blockers are preferable for long-term hypotensive therapy to prevent ocular surface inflammation.
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