Fixed topical combinations in glaucomatous patients and ocular discomfort

The purpose of this study was to verify the ocular comfort of a fixed topical combination of brinzolamide 1% plus timolol 0.5% suspension vs. dorzolamide 2% plus timolol 0.5% solution, both preserved with benzalkonium chloride (BAK), in patients with primary open-angle glaucoma (POAG) through subjective and objective methods. BAK is the most commonly used preservative in topical glaucoma medications.

62 subjects were examined and included in the analysis. Each patient was asked to complete a questionnaire on symptoms (Ocular Surface Disease Index) and then underwent a series of examinations. The Ocular Protection Index evaluated the risk of damage to the ocular surface, and was expressed as the ratio between fluorescein breakup time and blinking interval. These and other analyses were repeated 30 days after instillation of the new eye drop treatment.

The results demonstrated that patients enrolled with the preserved fixed combination of dorzolamide or brinzolamide represented a subgroup of patients in which the discomfort symptoms were supposedly justified by the presence of BAK used chronically in antihypertensive drops. Ocular discomfort scores were significantly higher with dorzolamide/timolol than brinzolamide/timolol (p < 0.0001).

This work shows the better tolerability of brinzolamide 1% plus timolol 0.5% suspension, compared with dorzolamide 2% plus timolol 0.5% solution. Fortunately, some of the adverse reactions induced by preserved eye drop glaucoma medication are reversible after removing the preservatives. Both the potential for added benefit and patient compliance should be considered when selecting ocular hypotensive therapy.