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Précis: Subliminal subthreshold transscleral cyclophotocoagulation (SS-TSCPC) with duty cycles 25% and 31.3% seems to be an effective approach to reduce intraocular pressure (IOP) in glaucoma that is refractory to medical management. Objective: The objective of this study was to compare the effectiveness and the tolerance of SS-TSCPC with a duty cycle of 25% versus 31.3% with Supra 810 nm Subliminal Quantel Medical laser stimulation for advanced glaucoma. Materials and Methods: This was a retrospective, single-center, comparative case series of patients treated by SS-TSCPC between January 2017 and July 2017. The diagnostic and inclusion criteria were patients with advanced and refractory glaucoma, defined as IOP >21 mm Hg on maximal tolerated medical therapy with or without previous glaucoma surgical procedures, a minimum follow-up of 12 months, and patients who refused or were poor candidates for additional filtering surgery or implantation of glaucoma drainage devices. The primary endpoint was surgical success defined as an IOP of 6 to 21 mm Hg or a reduction of IOP by 20% from baseline without an increase in glaucoma medication from baseline. The secondary endpoints were the mean IOP and best visual corrected acuity best-corrected visual acuity at 12 months after surgery, retreatment outcomes, glaucoma medications, and complications such as inflammation, uveitis, cataract, mydriasis, and phthisis. Results: Forty eyes of 32 patients were included: 20 eyes were subjected to SS-TSCPC with 31.3% duty cycle and 20 eyes with a 25% duty cycle. The surgical success of the TSCPC 12 months after the first procedure was better in the 31.3% duty cycle group (83.5%) than in the 25% duty cycle group (65%). The most common complications were inflammation (50%, 1 mo after surgery) and IOP spikes (increase in IOP of >25% from baseline within 1 mo of laser) in both groups. Inflammation was higher in the 31.3% duty cycle group. Conclusions: SS-TSCPC at 31.3% and 25% duty cycle seems to be an effective approach to reduce IOP in glaucoma that is refractory to medical management. SS-TSCPC at 31.3% duty cycle is more effective than the 25% duty cycle SS-TSCPC. However, the 31.3% duty cycle SS-TSCPC induces more inflammation than the 25% duty cycle SS-TSCPC. Each procedure should be considered on a case by case basis.