Original article
Effect of dorzolamide timolol combination versus timolol 0.5% on ocular bloodflow in patients with primary open-angle glaucoma

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Abstract

PURPOSE: Addition of dorzolamide to timolol in primary open-angle glaucoma shows augmented reduction of intraocular pressure. It is unknown as yet if addition of dorzolamide will alter hemodynamics.

METHODS: Fifteen patients with primary open-angle glaucoma were placed on a medication-dependent 1-week to 4-week washout that included maintenance on timolol. After washout, baseline measurements were taken (timolol). They were studied after a month on timolol or dorzolamide-timolol (Cosopt®; Merck, Inc, Whitehouse Station, New Jersey), with the second drug preceded by another month of timolol maintenance and second baseline measurements. At each visit, visual function, intraocular pressure, and ocular hemodynamics were monitored, including indocyanine green and fluorescein angiography and color Doppler imaging.

RESULTS: Cosopt® significantly reduced intraocular pressure (14.7 to 13.4 mm Hg, P < .05) and increased arteriovenous passage time (superior temporal artery) of fluorescein dye (2.13 to 1.76 seconds, P = .01) but had no effect on visual function.

CONCLUSIONS: When compared with timolol in primary open-angle glaucoma, Cosopt® augments ocular tension reduction and reduces the amount of time required for blood to pass through the superior retinal vasculature.

Section snippets

Methods

Fifteen patients with primary open-angle glaucoma were studied in a randomized, cross-over, double-masked design that included initial washout of medications other than timolol, maintenance treatment on timolol, and then study with either timolol or the combination of timolol and dorzolamide (Cosopt®; Merck, Inc, Whitehouse Station, New Jersey). All procedures were reviewed and approved by an institutional review board at Indiana University School of Medicine, and subjects signed informed

Results

The mean deviation of the visual field testing was unchanged by participation in the study (Table 1); the corrected pattern standard deviation was unaltered as well (Table 1). Neither timolol (control) nor timolol plus dorzolamide treatment affected visual acuity (Table 1), or altered contrast sensitivity at 3, 6, 12, or 18 cycles per degree (Table 1).

Intraocular pressure was significantly reduced by dorzolamide-timolol combination as compared with timolol alone (P < .05, Table 1). Intraocular

Discussion

Reduction of intraocular pressure remains the primary goal of glaucoma therapy. Although the β-adrenergic blockers have served as standard ocular hypotensive agents for many years, these medicines can provoke cardiovascular, pulmonary, central nervous system, and endocrine side effects.7 Dorzolamide is a safe, effective, and easily tolerated topical carbonic anhydrase inhibitor that retains the ocular hypotensive actions of systemic carbonic anhydrase inhibition without the accompanying side

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This work was supported in part by Grant EY10801 (AH) from the National Institutes of Health, Bethesda, Maryland, an unrestricted grant from Research to Prevent Blindness, New York, New York, and an unrestricted grant from Merck, Inc. Study medications were provided by Merck, Inc. A.H. is a recipient of the William and Mary Greve Award from Research to Prevent Blindness.

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