Greater Outflow Facility Increase After Targeted Trabecular Bypass In Angiographically Determined Low-Flow Regions
Published 2024 - 42nd Congress of the ESCRS
Reference: FP23.05 | Type: Free paper | DOI: 10.82333/1wa7-jd52
Authors: Clemens Strohmaier* 1 , Daniel Wanderer 2 , Xiaowei Zhang 2 , Daniel Stamer 3 , Fiona McDonnell 4 , Robert Weinreb 2 , Alex Huang 2
1Ophthalmology and Optometry,Johannes Kepler University,Linz,Austria, 2The Viterbi Family Department of Ophthalmology, Shiley Eye Center,University of California San Diego,San Diego,United States, 3Duke Eye Center,Duke University,Durham,United States, 4Moran Eye Center,University of Utah,Salt Lake City,United States
Purpose
Aqueous humor outflow in the trabecular meshwork is known to be segmental with areas exhibiting high- as well as low-flow. Current trabecular bypass surgery (MIGS), however, is not performed in specific locations. The purpose of this study was to investigate the impact of trabecular bypass surgery targeted to angiographically-determined high- versus low-aqueous humor outflow areas on outflow facility (C) ex vivo.
Setting
Ex-vivo comparative study.
Methods
From porcine (n= 14) and human (n=13) post-mortem eyes, anterior segments were dissected, mounted onto a perfusion chamber, and perfused using Dulbecco’s phosphate buffered solution containing glucose at a constant-flow rate to achieve a stable baseline facility (C). Fluorescein was perfused into the anterior chamber and used to identify high- and low-flow regions of the conventional outflow pathways. A 5 mm needle goniotomy was performed in either baseline high- or low-flow areas. Subsequently, C was quantitatively re-assessed and compared between “high-flow” and “low-flow” surgery eyes.
Results
In the porcine high-flow group (n=8), C increased from 0.31 ± 0.09 to 0.39 ± 0.09 µL/mmHg/min (P = 0.12). In the porcine low-flow group (n=6), C increased from 0.29 ± 0.03 to 0.56 ± 0.10 µL/mmHg/min (P< 0.001). In the human high-flow group (n=6), C increased from 0.38 ± 0.20 to 0.41 ± 0.20 µL/mmHg/min (P = 0.02). In the human low-flow group (n=7), C increased from 0.25 ± 0.11 to 0.32 ± 0.11 µL/mmHg/min (P< 0.001). There was statistically significant greater C increase comparing low- to high-flow groups in both porcine (0.07 ± 0.09 vs 0.27 ± 0.13, P = 0.007 µL/mmHg/min, high- vs. low-flow) and human (0.03 ± 0.03 vs 0.07 ± 0.02, P = 0.03 µL/mmHg/min, high- vs. low-flow) eyes.
Conclusions
Targeting surgery to low-flow areas of the trabecular meshwork yields greater outflow facility (C) increase compared to surgery in high-flow areas. In-vivo studies are needed to confirm this finding and translate it to improved efficacy of common MIGS procedures.