Dr Brubaker, one of the coauthors of the article1 that compared dorzolamide hydrochloride and timolol as suppressors of aqueous humor flow, has shown in previous studies2,3 that timolol has no effect on the flow of aqueous humor in sleeping subjects. By contrast, the use of acetazolamide is able to reduce the flow in sleeping subjects.2,3 In the study by Wayman et al,1 the aqueous humor flow was evaluated only at night during the peak efficacy period of timolol; the flow was not evaluated at other times when carbonic anhydrase inhibitors are still efficacious in inhibiting aqueous humor flow. Therefore, a conclusion that one of the drugs better suppresses aqueous humor flow can only be made after evaluating a 24-hour period.
Aharon Wegner, Ian A. Ugi, Alon Harris. Dorzolamide and Timolol as Suppressors of Aqueous Humor Flow. Arch Ophthalmol. 1998;116(8):1133. doi: