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This prospective, open-label experimental study assessing the efficacy of brimonidine 0.1% over the diurnal and nocturnal periods is the latest from Liu et al. (1881) who have substantially contributed to our understanding of the 24 hour effect of glaucoma medications. As was the case with timolol 0.5%, brimonidine 0.1%, which substantially lowers IOP during the diurnal period, was found to have no significant impact on IOP during the nocturnal period.
Brimonidine 0.1% was found to have no significant impact on IOP during the nocturnal period
This is despite brimonidine having a dual mechanism of action including inhibition of aqueous humor formation and increased uveoscleral outflow. The authors suggest that based upon their findings with three times daily dosing of brimonidine 0.1%, a dose of this agent 'immediately before bedtime does not seem necessary.' While none of the major randomized clinical trials in glaucoma assessed nocturnal IOP as an independent risk factor for glaucomatous disease, it is logical to hypothesize that it is best to lower IOP throughout the 24-hour period in such patients. Confirmatory studies looking at structural and functional endpoints in patients on various glaucoma therapies are needed and will undoubtedly be easier to perform when 24-hour IOP monitors becoming available in the near future. The impact of dosing times as predictors of visual outcomes when using various glaucoma medications will also be worthy of future study.