Outflow facility of single vs dual wall canalotomy

Abstract

Purpose : To investigate and quantify the additive effect of Schlemm’s canal outer wall canalotomy as an adjunct to standard inner wall goniotomy on outflow facility.

Methods : Fresh pairs of human donor eyes were used in a constant pressure perfusion method to measure the effect of trabecular±outer wall incision on outflow facility before (BL) and after Schlemm canal intervention (Treatment). One eye of each pair underwent either single-wall goniotomy (n=6) or dual-wall canalotomy (n=6), which comprised of outer wall canalotomy adjunct to single-wall goniotomy. The goniotomy consisted of 360 degrees of continuous excision of trabecular meshwork. Outer wall canalotomy was performed with a calibrated blade to administer a 200-µm deep incision of the outer wall of Schlemm’s canal intended to improve access to the collector channels and episcleral plexus. Outflow facility was measured before and after Schlemm canal intervention, and changes in outflow facility were compared between single-wall goniotomy and dual-wall canalotomy.

Results : Both dual wall canalotomy and single-wall goniotomy significantly increased outflow facility over baseline (p<0.05). Dual wall canalotomy resulted in an additional 35% improvement in outflow facility compared to inner wall goniotomy alone (57% vs 22% increase in outflow facility respectively).

Conclusions : Outer wall canalotomy may have an incremental improvement in outflow facility when performed in addition to standard goniotomy. This proof of concept study suggests that this surgical approach merits further investigation.

This abstract was presented at the 2023 ARVO Annual Meeting, held in New Orleans, LA, April 23-27, 2023.