Transscleral cyclophotocoagulation followed by cataract surgery: a novel protocol to treat refractory acute primary angle closure

BACKGROUND: To introduce a novel protocol to treat refractory acute primary angle closure (APAC): transscleral cyclophotocoagulation (TCP) followed by cataract surgery. METHODS: Thirteen APAC eyes (13 patients) were enrolled in this prospective case series as study group. All patients underwent emergency TCP (20 pulses of 2000 mW during 2000 ms applied to the inferior quadrant) followed by scheduled cataract surgery. They were compared to 13 age- and gender-matched patients treated with emergency phacotrabeculectomy. We recorded intraocular pressure (IOP), best corrected visual acuity (BCVA), and complications, and several ultrasound biomicroscopy (UBM) parameters before and after TCP. RESULTS: In the study group, IOP decreased from 51.5 ± 7.0 mmHg (mean ± standard deviation) before TCP to 16.4 ± 5.4 mmHg 1 day after TCP (P < 0.001). At 6 months, there was no significant difference in IOP between the study group (14.0 ± 3.4 mmHg) and control group (16.7 ± 4.3 mmHg; P = 0.090); IOP lowering medications were used by 0/13 in the study group and 2/13 patients in the control group (P = 0.48). At 6 months, there was no significant difference in BCVA between the study group and the control group (20/25 (20/200 to 20/25) and 20/30 (20/50 to 20/25), respectively; P = 1.0). The UBM parameters anterior chamber depth (P = 0.016), angle-opening distance at 500 μm (P = 0.011), and maximum ciliary body thickness (P < 0.001) increased significantly while the iris-ciliary process distance decreased significantly (P = 0.020) after TCP. CONCLUSIONS: TCP effectively lowers IOP and modifies the anterior chamber morphology in APAC; TCP followed by cataract surgery can be considered an alternative to treat refractory APAC but needs further evaluation. TRIAL REGISTRATION: This project was registered in Chinese Clinical Trial Registry (ChiCTR1800017475) at July, 31, 2018 (http://www.chictr.org.cn/edit.aspx?pid=29629&htm=4).