The Effectiveness and Safety of Micropulse Cyclophotocoagulation in the Treatment of Ocular Hypertension and Glaucoma

Abstract

To evaluate the effectiveness and safety of primary and adjunctive micropulse cyclophotocoagulation (MPCPC) in the treatment of ocular hypertension (OHT) and glaucoma. Retrospective cohort study. Ocular hypertension and all severities of glaucoma (including treatment-naïve and well-sighted eyes) and all types of glaucoma (including normal-tension glaucoma [NTG]). Consecutive eyes with glaucoma or OHT that underwent MPCPC (Iridex Cyclo G6 Glaucoma Laser System, Mountain View, CA) between 2016 and 2018 were identified. Intraocular pressure (IOP), visual acuity, glaucoma medications, and ocular adverse events. Three hundred ninety-nine MPCPC surgeries, on 342 eyes of 214 patients, were analyzed. Laser power ranged from 900 to 2800 mW. Main diagnoses in descending prevalence were primary open-angle glaucoma (55.9%), chronic angle-closure glaucoma (10.8%), neovascular glaucoma (9.0%), NTG (6.5%), and OHT (5.5%). Mean baseline IOP was 19.8±7.4 mmHg and IOP reduction was 22.7%, 20.2%, 20.7%, and 23.7% at postoperative months (POMs) 1, 3, 6, and 12 (P < 0.0001 for all time points). The end point of 20% or more mean IOP reduction from baseline was achieved by 67.8% of the study cohort at POM 12. Additional mean IOP reduction of 16.4% (P < 0.0001) was achieved with each re-treatment. Analysis based on IOP stratification demonstrated 30.5% mean IOP reduction at POM 12 when baseline IOP was more than 21 mmHg and 20.1% when it was 21 mmHg or less (71% of overall cohort; P < 0.0001). Analysis based on laser power stratification demonstrated mean IOP reduction of 31.5% at POM 12 with laser power of 2500 mW or more and 17.8% with laser power of less than 2500 mW (P < 0.02). Overall, the mean number of topical glaucoma medications was unchanged from baseline to POM 12. Greater baseline IOP and number of baseline topical glaucoma medications were significant predictors of effectiveness in the regression analysis. No patients demonstrated persistent inflammation or hypotony, phthisis bulbi, or sympathetic ophthalmia. In patients with OHT or glaucoma, MPCPC demonstrated effectiveness and safety in IOP reduction sustained to 1 year. Baseline IOP of 21 mmHg or less subgroup demonstrated a more limited response. A dose-response relationship is suggested with respect to laser power and repeat treatments.