Eric S Tam, MD
A single drop of brimonidine 0.15% instilled into the eye preoperatively significantly decreased the severity of subconjunctival haemorrhage after femtosecond laser-assisted cataract surgery (FLACS), reported Eric S Tam, MD, at the 2020 ASCRS Virtual Meeting.
“Subconjunctival haemorrhage is a common side-effect following FLACS. Brimonidine is a selective alpha-1 adrenergic agonist that lowers IOP and has a vasoconstrictive effect, and its preoperative use to reduce conjunctival haemorrhage has been studied for various ophthalmic procedures, including LASIK and intravitreal injections,” said Dr Tam, University of Toronto, Toronto, Canada.
“To our knowledge, this is the first study to evaluate the vasoconstrictive effect of brimonidine or any other agent for FLACS. In addition, we believe it is the first to introduce an objective, standardised method for quantifying subconjunctival haemorrhage following ophthalmic procedures.”
The efficacy of brimonidine to reduce subconjunctival haemorrhage after femtosecond laser suction ring application was investigated in a prospective, masked study. Patients were randomised to receive the usual preoperative eye drops with or without one drop of brimonidine 0.15%. Dr Tam performed all surgeries using the same femtosecond laser and phacoemulsification platform.
Subconjunctival haemorrhage was evaluated using images obtained prior to preoperative drop instillation and 15 minutes after surgery using the Oculus Keratograph M5. A Bulbar Redness Score (BRS) and Analyzed Area (AA) were recorded. Patients were excluded if they were on anticoagulation therapy, had prior conjunctival surgery, experienced an intraoperative complication, or if the Analyzed Area was less than 25 mm2 or differed by more than 10% between preop and postop values.
“These stringent criteria were applied to ensure that the pairs of preoperative and postoperative images were of comparable quality for analysis,” Dr Tam explained.
The final analysis included 25 brimonidine-treated eyes and 37 control eyes. Mean age, gender distribution, and underlying medical conditions were similar in the two groups. Mean BRS and mean AA values did not differ significantly between the two study groups either preoperatively or postoperatively. There was also no statistically significant difference between groups in the mean change in AA from preop to postop.
However, compared with the preoperative value, the mean BRS decreased postoperatively in the brimonidine group and increased postoperatively in the control group. The difference between groups for the mean change values was statistically significant (p=0.03).
Discussing the study’s limitations, Dr Tam acknowledged that it had a low sample size. There was also a trend towards a higher preoperative BRS in the study group (p=0.07). In addition, he suggested that use of phenylephrine 10% for pupil dilation preoperatively may have partially masked the effects of brimonidine.
Eric S Tam: es.tam@utoronto.ca
