92 people used brimonidine gel or the same gel without the drug for 8 days and reported on their own redness and how it made them feel. Those on brimonidine rated themselves better. The study is small and very short, and it measured what people said rather than what an examiner graded, so it says little about how the gel performs over months.
Layton AM, Schaller M, Homey B, et al. Brimonidine gel 0.33% rapidly improves patient-reported outcomes by controlling facial erythema of rosacea: a randomized, double-blind, vehicle-controlled study. J Eur Acad Dermatol Venereol. 2015;29(12):2405-2410.