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The effect of dorzolamide on aqueous humor dynamics in normal human subjects during sleep
B D Vanlandingham1, T L Maus, R F Brubaker
1Mayo Medical School, Rochester, Minnesota, USA.
Objective:
The purpose of the study was to measure the effect of the topical carbonic anhydrase inhibitor, 2% dorzolamide hydrochloride, on the rate of aqueous humor flow in sleeping humans.
Design:
A randomized, double-masked, placebo-controlled study.
Participants:
Twenty-five normal human subjects.
Intervention:
Topical instillation of 2% dorzolamide hydrochloride versus topical placebo.
Main Outcome Measures:
Rate of aqueous humor flow in sleeping humans and intraocular pressure immediately after awakening from sleep.
Results:
The rate of flow in sleeping subjects at night (12 AM to 6 AM) was 1.28 +/- 0.30 microliters/min (mean +/- standard deviation; n = 25) in placebo-treated eyes, whereas the nighttime flow in dorzolamide-treated eyes was 1.17 +/- 0.38 microliters/min (P = < 0.001), resulting in a nighttime reduction of 9% (P = 0.032). In contrast, the daytime (8 AM to 4 PM) rate of flow in ambulatory subjects was 2.97 +/- 0.64 microliters/min in placebo-treated eyes and 2.60 +/- 0.63 microliters/min (P = 0.032) in dorzolamide-treated eyes, resulting in a daytime reduction of 13% (P = < 0.001).
Conclusions:
Topically administered dorzolamide hydrochloride is effective for reducing the rate of aqueous humor flow in normal human eyes during the day and at night during sleep. The efficacy of dorzolamide at these two times is approximately half that of systematically administered acetazolamide.