Exit strategies in canaloplasty: intraoperative conversion into 180-degree trabeculotomy or 360-degree trabeculotomy in cases of unsuccessful catheterisation of Schlemm's canal: influence of degree of canal cleavage.

Purpose: To investigate the safety and efficacy of intraoperative conversion of unsuccessful canaloplasty technique into 180-degree metal or 360-degree suture trabeculotomy.

Methods: In this retrospective observational case series, 35 eyes of 35 patients with open-angle glaucoma (OAG) who had undergone unsuccessful canaloplasty technique and underwent intraoperative conversion were studied. In 17 eyes (group A), the procedure was converted into 180-degree metal trabeculotomy because of unsuccessful circumferential Schlemm's canal (SC) catheterisation. Group B included 18 eyes that were converted into 360-degree trabeculotomy because of cheese wiring of tension suture through the trabecular meshwork (TM) after successful complete catheterisation of SC.

Results: Median preoperative IOP was 22.0 mmHg (range 16-34) in group A, and 22.0 mmHg (range 15-48) in group B. Median IOP was significantly reduced in both groups postoperatively, at the 12-month examination to 15.0 mmHg (range 9-21) representing a reduction of 36 % in group A, and to 14.5 mmHg (range 8-21) representing a reduction of 34 % in group B. Median glaucoma medication number decreased significantly from 4 (range 2-4) and 3 (range 1-4) preoperatively to 2 (range 0-4) and 1 (range 0-3) at 12 months in groups A and B respectively. Hyphema was the commonest complication, with an incidence of 76 % in group A and 78 % in group B.

Conclusion: 180-degree metal or 360-degree suture/catheter trabeculotomy are safe and effective surgical backup methods to control IOP in cases of unsuccessful intracanalicular placement of tension suture during canaloplasty surgery.