Acute and chronic ocular symptoms of dorzolamide 2% compared with placebo

To characterize and compare the ocular comfort and symptoms of dorzolamide and tear-replacement drops (placebo) in healthy volunteers.

Subjects were randomized in a double-masked fashion to receive each medicine for 6 days twice daily. Patients used a visual analog scale to assess the quality and intensity of pain temporally after initial (acute) dosing and after 6 days of chronic dosing. The visual analog scale, an objective measure of pain, allows a subject to grade their perceived intensity of pain on a line between 0 and 100 mm.

Of 28 subjects enrolled in the study, 27 completed the protocol (1 subject was lost to follow-up). Dorzolamide demonstrated statistically greater peak ocular pain (21.4 +/- 22.3 mm) compared with placebo (1.9 +/- 4.4 mm) (P<0.0001) after chronic dosing. Time of mean peak pain for dorzolamide products was 15 seconds after dosing. The pain was statistically greater with dorzolamide compared with placebo for 50 seconds after dosing. On average the discomfort associated with dorzolamide lasted 38.9 +/- 17.9 seconds after dosing. The average pain per second for the first minute was 7.1 +/- 10.1 mm for dorzolamide. No differences in pain intensity were observed after acute and chronic dosing. The discomfort with dorzolamide was characterized after chronic dosing as "burning" (14.8 +/- 25.0 mm) and was associated with tearing (1.9 +/- 5.2 mm).

Dorzolamide caused more ocular pain after instillation than placebo. However, the pain was characterized as mild and quickly resolved.