Persistent Hypotony and Annular Ciliochoroidal Detachment After Microhook Ab Interno Trabeculotomy

Precis: Creation of a cyclodialysis cleft can be a mechanism of ciliochoroidal detachment (CCD) and associated persistent hypotony after microhook ab interno trabeculotomy (mu LOT). Aims: To report persistent hypotony after mu LOT, a minimally invasive glaucoma surgery (MIGS). Subjects and Methods: This observational case series included 4 consecutive cases (3 men, 1 woman; mean age, 48.8 +/- 15.1 y) of persistent hypotony that developed after mu LOT between May 2015 and March 2018. The patients' data and surgical results were obtained from the medical charts. Results: All patients had open-angle glaucoma (2 juvenile, 1 primary, and 1 pigmentary) and were myopic (axial lengths, >24 mm). Two patients had undergone previous refractive surgery. mu LOT alone was performed in 2 cases and combined with cataract surgery in 2 cases. In all cases, hypotony below 5 mm Hg was recorded 1 day postoperatively and sustained. In all cases, ultrasound biomicroscopy showed an annular CCD; communication between the anterior chamber and suprachoroidal space was detected in 3 of 4 cases. The hypotony resolved in 3 of the 4 cases from 2 to 8 months postoperatively, that is, spontaneously in 2 cases (cases 1 and 4) and after sulfur hexafluoride gas injection into the anterior chamber in 1 case (case 2). CCD resolution accompanied remarkedly high intraocular pressure, which required filtration surgeries. The incidence of persistent hypotony was 0.7% (4/547 eyes). Conclusions: After MIGS, persistent hypotony because of CCD rarely occurs. Increased uveoscleral outflow because of LOT or creation of a cyclodialysis cleft by traction of the pectinate ligament can be a mechanism of CCD development. Young age and myopia can be risks for cyclodialysis cleft formation and hypotony maculopathy after MIGS.