Authors: Harrish Nithianandan, Ali Salimi, Huda A. Al Farsi, Hady Saheb, MD, MPH, FRCSC.
McGill University.

Author Disclosure Block: H. Nithianandan: None. A. Salimi: None. H.A. Al Farsi: None. H. Saheb, MD, MPH, FRCSC: None.

Abstract Body:

Purpose: Following a successful gonioscopy-assisted transluminal trabeculotomy (GATT) procedure, the posterior leaflet of the trabecular meshwork may remain disconnected from the anterior leaflet of the trabecular meshwork, or may return to its anatomical position. This study examined whether the extent of the persistent trabecular shelf (TS) identified via swept-source optical coherence tomography (SS-OCT) was related to postoperative outcomes of GATT.
Study Design: IRB-approved Retrospective Interventional Case Series.
Methods: All GATT cases completed by the principal investigator between January 2016 to March 2020 were identified. The clinical variables of interest were patient demographics, visual acuity, visual field parameters, findings on slit lamp biomicroscopy and gonioscopy, as well as parameters of optic nerve head imaging. Postoperatively, the Casia SS-1000 OCT (Tomey, Nagoya, Japan) was used to quantify the extent of persistent TS, namely as a proportion of the 360-degree angle. Eyes were divided into two groups (high-extent vs. low-extent TS) based on a median split of the TS extent distribution (60°). The main outcome was the odds of surgical success (defined as final intraocular pressure (IOP) <21 mmHg and ≥20% IOP reduction, no need for additional glaucoma surgery, and no loss of light perception). General linear model analyses and logistic regression analyses were computed to compare continuous and categorical outcomes, respectively, as a function of TS extent.
Results: A final sample of 69 GATT cases (39% combined with phacoemulsification) among 56 patients (mean age: 64±15 years, 61% male) with a median length of follow-up of 11 months were included. In the high-extent group (≥60º of TS), surgical success was achieved in 71% of eyes vs. 59% in the low-extent group (odds ratio of success=1.68, 95%CI: 0.61 - 4.59, p=0.31). When eyes were divided into quartiles based on TS extent, 58% of Q1 eyes, 53% of Q2 eyes, 85% of Q3 eyes and 71% of Q4 eyes achieved success (p=0.25).
Conclusions: Clinically meaningful trends of GATT efficacy that may be associated with the extent of persistent TS measured on SS-OCT were observed in this interventional case series. The results of this study may help clinicians prognosticate clinical outcomes at an early postoperative stage in patients undergoing GATT.