Diluted brimonidine for improving early postoperative symptoms and subconjunctival hemorrhage after PRK and LASIK

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Abstract
Purpose: To assess whether low-concentration brimonidine (0.025%) improves early postoperative signs and symptoms following femtosecond laser-assisted in situ keratomileusis and photorefractive keratectomy without affecting pupil diameter or flap safety. Methods: This prospective, randomized, double-masked, contralateral-eye, single-center study was conducted between January and September 2024. In each patient, one eye received 0.025% brimonidine 15–30 min before surgery (mean: 21.3 ± 2.4 min), whereas the fellow eye received 0.15% sodium hyaluronate (control). Primary outcomes on postoperative Day 1 included subconjunctival hemorrhage laser-assisted in situ keratomileusis and patient-reported symptoms (0–10 scale; composite score). Pupil diameter was measured pre-ablation. Statistical analyses included McNemar and paired t tests, with a significant threshold of α=0.05. Results: A total of 124 patients were included (54 laser-assisted in situ keratomileusis and 70 photorefractive keratectomy). Pupil diameter did not differ significantly between brimonidine-treated and control eyes (laser-assisted in situ keratomileusis: 2.63 ± 0.47 vs. 2.69 ± 0.42 mm, p=0.273; photorefractive keratectomy: 2.56 ± 0.44 vs. 2.61 ± 0.39 mm, p=0.116). In laser-assisted in situ keratomileusis, subconjunctival hemorrhage occurred less frequently in brimonidine-treated eyes both intraoperatively (9.3% vs. 46.3%, p<0.001) and on postoperative Day 1 (9.3% vs. 50.0%, p<0.001). Composite symptom scores were significantly lower in brimonidine-treated eyes in both laser-assisted in situ keratomileusis and photorefractive keratectomy groups (p=0.001 for both). Conclusions: Preoperative administration of low-concentration brimonidine (0.025%) significantly reduced subconjunctival hemorrhage in laser-assisted in situ keratomileusis without comprising flap integrity. It also improved early postoperative symptoms in laser-assisted in situ keratomileusis and photorefractive keratectomy, without affecting pupil diameter. These findings support the use of dilute brimonidine as a safe and effective adjunct to enhance the immediate postoperative experience in refractive surgery.