Background: Traditional continuous diode laser transscleral cyclophotocoagulation (TCW-TSCPC) has been used for decades to reduce intraocular pressure (IOP) by decreasing aqueous humor (AH) production in patients with glaucoma. Micropulse cyclophotocoagulation (MP-TSCPC) and slow coagulation (SC-TSCPC) are the newest transscleral cyclophotocoagulation (TSCPC) techniques that result in lower inflammation and complication rates compared to the traditional technique. Most publications on TSCPC are case series with a retrospective design with different treatment protocols. The objective of this manuscript is to describe the protocol of a randomized clinical trial (RCT) designed to compare the efficacy and safety of MP-TSCPC and SC-TSCPC in patients with refractory glaucoma followed for 12 months.

Methods: This is a parallel, double-arm single-center, double-masked, RCT that will include eyes with refractory glaucoma. Patients with corrected visual acuity (BCVA) ≤ 20/60, IOP > 21 mmHg, and age ≥ 18 years will be randomized to cyclophotocoagulation using the SC-TSCPC or MP-TSCPC techniques. Follow-up visits will be 1 day, 7 days, 30 days, 3, 6, and 12 months after the procedure. Complete success will be defined as an IOP between 6 and 20 mmHg and a minimum of 30% IOP reduction from baseline, without hypotensive medications. Qualified success will be defined by the same parameters but allowing the use of medication. All follow-up examinations will include determination of BCVA, IOP measurement, slit lamp biomicroscopy, fundoscopy, and macular optical coherence tomography (OCT). The number of hypotensive medications and the occurrence of complications will also be documented.

Conclusions: Our study was designed to compare the efficacy and safety of the two most used TSCPC techniques. Most published studies are retrospective and compare the two new techniques only with the traditional technique. This is, to our knowledge, the first RCT comparing MP-TSCPC and SC-TSCPC techniques. Background: Retrospectively registered at the Registro Brasileiro de Ensaios Clínicos (ReBEC) platform RBR-5pckbhj on December 15, 2023. The study was approved by the Ethics Committee of the University of Campinas, Brazil.