Background: To compare the tolerability of commonly prescribed topical glaucoma medications by determining frequency and bother of side effects, patient satisfaction with their medication, and the chance of discontinuation of eye drops.
Methods: The tolerability of topical glaucoma medication was studied in glaucoma patients from nine hospitals. The frequency and severity of side effects was investigated together with patient satisfaction with the medication and the probability to change medication due to reported side effects. To register side effects of topical glaucoma medication, patients were requested to fill in a questionnaire based on "the Comparison of Ophthalmic Medications for Tolerability" (COMTOL) questionnaire supplemented with items based on the most frequently observed and severe side effects.
Results: The number of patients responding was 3,333 (87%). Most patients (79%) were satisfied with their eye medication. The median score for ocular side effects was 58 on a scale ranging from 0 to 320. The probability that medication would be changed by the ophthalmologist at the next visit due to reported side effects occurring since the patients' last or last but one visit to the ophthalmologist was 9%. The most frequently prescribed drugs were timolol, latanoprost, and the fixed combinations of dorzolamide/timolol (Cosopt) and latanoprost/timolol (Xalcom). Only small differences in tolerability were found between these drugs.
Conclusions: The tolerability of timolol, latanoprost, and the fixed combinations of latanoprost/timolol (Xalcom) and dorzolamide/timolol (Cosopt) seem to be comparable. Patients are satisfied with their glaucoma medication and have a low chance of discontinuation of eye drops due to side effects.