Aim: To identify the ideal treatment protocol and success predictors for double-session micropulse transscleral (MP3) laser for glaucoma management. Materials and methods: Patients who underwent double-session MP3, with a minimum follow-up of 6 months, were retrospectively investigated. Logistic regression analysis was used to verify preoperative success predictors. The following comparisons were made: (1) Between eyes that obtained surgical success vs failure, (2) According to the time required for MP3, and (3) Considering only eyes that required retreatment. Results: A total of 191 eyes from 148 patients were included. The preoperative intraocular pressure (IOP) was significantly higher than at last follow-up visit (27.3 ± 6.9 vs 14.6 ± 6.0 mm Hg, p < 0.001). Success was observed in 90.5% of the eyes. On logistic regression analysis with preoperative IOP and MP3 time as independent variables, only previous IOP was identified as a statistically significant factor (p = 0.004), with lower IOP relating to higher success. Eyes that required lower MP3 time underwent more MP3 procedures than those with higher MP3 time (1.2 ± 0.5 vs 1.1 ± 0.3, p = 0.03). In the 36 eyes that underwent retreatment, preoperative IOP was higher (31.6 ± 7.4 vs 26.3 ± 6.4 mm Hg, p < 0.001); eyes with successful IOP treatment had a higher MP3 treatment time at the first surgery than eyes with failed IOP correction (364.1 ± 68.2 vs 330.0 ± 18.0 seconds, p = 0.02). Conclusion: Thus, an ideal double-session MP3 protocol should use a high laser energy at the first surgery, and a high preoperative IOP can be considered as a predictor of surgical failure. Clinical significance: This is the first study to give special attention to the double-session MP3 protocol and success predictors.