New suture probe canaloplasty combined with suprachoroidal collagen implantation

Abstract

Purpose: To present the modified surgery technique of new suture probe canaloplasty with a specially prepared monofilament 4.0 polypropylene suture combined with suprachoroidal drainage (ScD) and collagen sheet implantation for non-penetrating glaucoma surgery.

Methods: Prospective study with a twelve months follow-up. A standard 4/0 polypropylene suture (ProleneTM by Ethicon; thickness: approximately 250 m) is cut and shaped with an ophthalmic knife (MANI® Crescent Knife, Mani Inc 8-3 Kiyohara Industrial Park, Utsunomiya, Tochigi 321-3231, Japan) to create a blunt end without sharp or compressed edges. This improves suture probe canaloplasty by providing a more stable and smoother probing device. Schlemm's canal is prepared using the standard technique of canaloplasty with suprachoroidal drainage. Then, instead of using the canaloplasty microcatheter or the previously published 6/0 double-helix suture, Schlemm's canal is probed with the blunt ending of the 4/0 Prolene suture. After successful 360-degree probing, a doubled 10/0 polypropylene tension suture is threaded through the tip of the 4/0 suture. The 4/0 suture is then pulled back and the 10/0 tension sutures are tied at both ends to tension Schlemm's canal. A special collagen sheet (Ologen®) is placed in suprachoroidal space, and the scleral flap is firmly sewed.

Results: 115 eyes were included in this prospective study. In 113 cases the Schlemm's canal could completely be probed with the suture probe and canaloplasty with ScD and collagen sheet implantation succeeded. In two cases the intervention was transformed to 360-degree suture trabeculotomy due to an intraoperative cheese-wiring. Twelve months after successful new suture probe canaloplasty with ScD and Collagen Implantation the IOP had decreased by 37.1% (from 21.6 ± 6.0 mmHg with 3.3 different IOP lowering eye drops to 13.5 ± 3.5 mmHg with 1.0 eye drops). 16 Patients did not achieve sufficient IOP levels and underwent 360-degree suture trabeculotomy during the follow-up. One patient had to be treated with further glaucoma surgery to achieve a sufficient IOP level. Complications were hyphema, postoperative IOP elevation and transient hypotony. No serious or sight-threatening complications occurred.

Conclusion: New suture probe canaloplasty with ScD and collagen sheet implantation yields the opportunity to conduct a cost-effective canaloplasty easier and less complicated than with the previously described method with the twisted 6/0 suture. The safety profile and IOP lowering effect is comparable. In cases where complete probing fails, there is still the opportunity to switch to suture trabeculotomy over the majorly probed part of Schlemm's canal. The pressure lowering effect of the deep sclerectomy with ScD and suprachoroidal collagen sheet implant seems to have an additional impact on the sufficient pressure lowering procedure.

Keywords: Canaloplasty; Collagen sheet implantation; Deep sclerotomy; Glaucoma revision surgery; Non-penetrating glaucoma surgery; Schlemm’s canal; Suprachoroidal drainage; Suture probe; Trabeculotomy.