Researchers in Toronto have found that administering topical brimonidine 20 minutes before intravitreal injection of anti-VEGF agents significantly decreased the transient post-injection intraocular pressure (IOP) spike in non-glaucomatous eyes. Without prophylaxis, the immediate post-injection IOP was, on average, 42mm Hg and reached as high as 81mm Hg. Comparatively, topical brimonidine significantly decreased the IOP spikes to an average of 34mm Hg with a high of 63mm Hg.

The study looked at 58 eyes of 55 patients who were randomly assigned to no prophylaxis or topical brimonidine tartrate 0.15% administered 20 minutes prior to injection in one of two consecutive visits. Researchers obtained IOP measurements immediately and then 10 minutes and 20 minutes after injection during the visits for all study subjects. The mean baseline IOP was 15.3mm Hg.

The patients with prophylactic topical brimonidine had a lower IOP at all three time points, as well as a smaller proportion of eyes with IOP elevation of greater than 20mm Hg from pre-injection and IOP greater than 50mm Hg immediately after injection. Without prophylaxis, two eyes of two patients had an IOP of greater than 70mm Hg immediately after injection and underwent anterior chamber paracentesis. 

According to researchers, using brimonidine as prophylaxis could be readily adopted and easily incorporated into the current practice of intravitreal anti-VEGF injections, potentially serving as an effective method for reducing post-injection IOP spikes in both glaucomatous and non-glaucomatous eyes.