Visco-Circumferential-Suture-Trabeculotomy Versus Rigid Probe Viscotrabeculotomy in Primary Open Angle Glaucoma

Introduction Glaucoma is the leading cause of irreversible visual loss worldwide. Primary open angle glaucoma (POAG) is the most common type of glaucoma accounting for 74% of all glaucoma cases (1, 2). Trabeculectomy is still the most commonly performed glaucoma surgery worldwide (3). However, trabeculectomy has several vision-threatening complications as ocular hypotony, choroidal detachment and bleb related infections (4). Therefore, in the recent years, bleb independent less invasive procedures as canaloplasty (5,6), gonioscopy-assisted transluminal trabeculotomy (GATT) (7,8) and ab externo circumferential trabeculotomy (6,9) have become increasingly popular because of their great efficacy and excellent safety profile. Despite the successful outcomes and the few postoperative complications of GATT in juvenile and adult POAG, however on the downside, surgeons with less experience performing GATT procedure may initially struggle with it. Also, GATT requires a goniolens and a reasonably clear cornea to visualize the nasal angle. Introducing instruments into the anterior chamber also poses an increased risk for damage to intraocular structures (10, 11). Looking at ab externo trabeculotomy, for many years, many authors have demonstrated its efficacy in lowering IOP in congenital (12, 13, 14), juvenile (15, 16) and adult open angle glaucomas (6, 9, 17). Trabeculotomy ab externo techniques include conventional probe trabeculotomy, viscotrabeculotomy (VT) (17), 360 - degree suture trabeculotomy (9) , viscocircumferential -suture trabeculotomy (VCST) (14) and trabeculotomy with the use of illuminated microcatheter.(15,18). Although the illuminated microcatheter helps to cannulate SC safely, however its cost constitutes a financial burden in many countries. VCST was proved to be effective for reduction of IOP in PCG as it offers the advantages of performing 360 circumferential trabeculotomy with a great ease and a low cost (14). The aim of the present study was to compare the surgical outcomes of (VCST) and rigid probe VT in patients with POAG.

Purpose:

This study aims to compare the surgical outcomes of (VCST) and rigid probe VT in patients with POAG.

Methods:

The study is conducted at Mansoura university ophthalmic Center. Sample size has been calculated using Cochran's formula with a 95% confidence level and Z value of 1.95. This comparative study was conducted on 166 eyes of 107 patients with medically uncontrolled primary open-angle glaucoma diagnosed and operated upon in the Mansoura Ophthalmic Center of Mansoura University, Egypt between February 2017 and December 2020. The study follows the tenets of the Declaration of Helsinki. All patients of the study received a clear explanation of the study design, the surgical procedures and their possible consequences and they gave written informed consent.