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S. Rai, S. Fan, V. Gulati, M. Zhao, H. Liu, C. B. Camras, C. B. Toris; Day and Night Differences in Aqueous Humor Dynamics and IOP in Ocular Hypertensive Patients Treated With Dorzolamide. Invest. Ophthalmol. Vis. Sci. 2010;51(13):146.
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To evaluate the effect of topical dorzolamide on intraocular pressure (IOP) and aqueous humor dynamics during the day and night in patients with ocular hypertension.
Thirty patients were enrolled in the 4-visit randomized, double-masked study following screening and 6 weeks of washout. On the two daytime visits from 9 AM to 3 PM (baseline and following two weeks of twice daily dosing of drug), intraocular pressure (IOP) was determined by pneumatonometry, aqueous flow (Fa) and outflow facility by fluorophotometry (Cfl), episcleral venous pressure (Pev) by venomanometry and outflow facility again by two minute tonography (Cton), central corneal thickness (CCT) and anterior chamber depth (ACd) by pachymetry and blood pressure by sphygmomanometry. Two days after each daytime visit, all measurements except for Cfl and Pev were repeated between the hours of 10 PM and 5 AM. Uveoscleral outflow was calculated by the Goldmann equation. Baseline and dorzolamide treatment were compared using two-tailed paired t-tests.
Dorzolamide significantly (p<0.001) reduced IOP by 16% at 11AM (two hours after the previous dose) but not at 9 AM (12 hours after the previous dose, 7% drop, p=0.07) or at any IOP overnight (10 PM, midnight, 2 AM, 5 AM). Compared to baseline, dorzolamide during the day reduced aqueous flow by 16% (p=0.03). Dorzolamide did not change any of the day versus night differences in IOP and aqueous humor dynamics found at baseline (reduced Fa and Fu and increased CCT). Physiological nighttime suppression of Fa seen at baseline was not decreased further by dorzolamide use (47%, p<0.001).
Dorzolamide reduced IOP during the day in ocular hypertensive patients by reducing aqueous flow. It had no effect on IOP or aqueous humor dynamics at night nor did it affect CCT, ACd or blood pressure day or night.
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