Dose-Effectiveness Optimizing in Micropulse Transscleral Cyclophotocoagulation: A Cohort Study in Refractory Glaucoma

To characterize the clinical outcomes, safety profile, and dose-response relationship of micropulse transscleral cyclophotocoagulation (MPCPC) utilizing augmented dose protocols in Chinese patients with refractory glaucoma.

Retrospective, single-center study.

Patients treated with MPCPC at Zhongshan Ophthalmic Center from August 2022 to August 2024.

Laser parameters of MPCPC were standardized at 2000 mW and a 31.3% duty cycle, with patients stratified into 3 groups based on treatment duration: 160 seconds, 200 seconds, and 240 seconds.

Participants were followed up for 12 months to assess changes in best-corrected visual acuity, intraocular pressure (IOP), and number of antiglaucoma medications. Treatment success was defined as a final IOP between 5 and 21 mmHg or a ≥ 20% reduction from baseline, without the need for increased antiglaucoma medications or surgical re-intervention.

A total of 229 eyes from 229 patients were analyzed: 160 s (n = 66), 200 s (n = 35), and 240 s (n = 128). At 12 months postoperatively, the 240 s group achieved a 38.7% IOP reduction, which was significantly superior to the 25.5% reduction observed in the 160 s group (P = 0.028). Linear regression identified a significant dose effect, with each 40-second increment in laser duration associated with an additional 5.9% IOP reduction (β = 0.059, P = 0.035). Kaplan-Meier survival analysis revealed the highest cumulative success probability in the 240 s group (68.7%), followed by the 200 s group (58.1%) and the 160 s group (53.6%) (P = 0.040). Multivariate Cox regression confirmed that eyes with shorter treatment duration and eyes with longer axial length had a higher risk of treatment failure (P < 0.05). Notably, a decline in visual acuity occurred only in the 160 s group (P = 0.036). The number of antiglaucoma medications was significantly reduced in all 3 groups compared with baseline (P < 0.01). Complication rates did not differ significantly among the 3 groups (P = 0.155).

MPCPC constitutes a safe and potent modality for IOP reduction, exhibiting a dose-dependent effectiveness. The augmented-dose protocols of 200-240 s seem to optimize long-term IOP control. Patients with longer axial length have a potential risk of treatment failure, which is likely attributable to posterior displacement of the ciliary body.

The authors have no proprietary or commercial interest in any materials discussed in this article.