Settings and effectiveness of the revised probe compared to the original probe for micropulse transscleral cyclophotocoagulation

Purpose: The goal of this study was to compare the settings and effectiveness of the original P3 and revised P3 probes for micropulse transscleral cyclophotocoagulation. Methods: This retrospective cross sectional study includes a total of 56 patients with glaucoma who received micropulse transscleral cyclophotocoagulation. 32 patients received treatment with the original P3 probe and 24 received treatment with the revised P3 probe. Success was defined as a 20% reduction in intraocular pressure. Laser settings, pre-op and post-op intraocular pressures, and pre-op and post-op medications were assessed. Results: A 20% IOP reduction was achieved in 50% of patients in the original probe vs. 58.3% in the revised probe at one month (P = 0.536) and 71.9% vs. 50% at three months (P = 0.094), respectively. The revised P3 probe used higher values of power (2500 mW vs. 2023 mW, P < 0.0001), total duration (217 s vs. 179 s, P < 0.0001), and energy (170 J vs. 113 J, P < 0.001). There was a significant decrease in IOP lowering meds with the original probe at one month (-0.9 +/- 1.5 vs. -0.0 +/- 0.7, P = 0.010), but this was not seen at three months. Conclusions: There is no significant difference in IOP lowering effect between probes despite the revised probe using higher total energy. The original probe may be associated with fewer medications at 1 month, but not at 3 months. Further studies with longer follow up are needed to optimize the treatment parameters in order to maximize effectiveness while limiting side effects.