Angle stability and outflow in excisional ab interno trabeculectomy with active versus passive chamber management

Chao Wang; Yalong Dang; Susannah Waxman; Xiaobo Xia; Robert N Weinreb; Nils A Loewen

doi:10.7287/peerj.preprints.2762v2

Angle stability and outflow in excisional ab interno trabeculectomy with active versus passive chamber management

Chao Wang¹, Yalong Dang¹, Susannah Waxman¹, Xiaobo Xia², Robert N Weinreb³, Nils A Loewen ¹

1 Department of Ophthalmology, School of Medicine, University of Pittsburgh, Pittsburgh, Pennsylvania, United States

2 Department of Ophthalmology, Xiangya Hospital, Central South University, Changsha, Hunan, China

3 Shiley Eye Institute, Hamilton Glaucoma Center and Department of Ophthalmology, University of California, San Diego, La Jolla, California, United States

DOI: 10.7287/peerj.preprints.2762v2

Published: 2017-02-05
Accepted: 2017-02-05

Subject Areas: Drugs and Devices, Ophthalmology, Surgery and Surgical Specialties
Keywords: trabeculotomy, goniotomy, glaucoma surgery, anterior segment optical coherence tomography, surgical training, ab interno trabeculectomy, MIGS, microincisional glaucoma surgery, anterior chamber, pig model

Copyright: © 2017 Wang et al.
Licence: This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, reproduction and adaptation in any medium and for any purpose provided that it is properly attributed. For attribution, the original author(s), title, publication source (PeerJ Preprints) and either DOI or URL of the article must be cited.

Cite this article: Wang C, Dang Y, Waxman S, Xia X, Weinreb RN, Loewen NA. 2017. Angle stability and outflow in excisional ab interno trabeculectomy with active versus passive chamber management. PeerJ Preprints 5:e2762v2 https://doi.org/10.7287/peerj.preprints.2762v2

Abstract

Purpose: To compare the intraoperative angle stability and the postoperative outflow of two ab interno trabeculectomy devices that excise the trabecular meshwork. The newer device has an active aspiration and irrigation port while the older requires viscoelastic to maintain the anterior chamber. We hypothesized that anterior segment optical coherence tomography (ASOCT) allows quantifying the intraoperative behavior in a microincisional glaucoma surgery (MIGS) pig eye training model.

Methods: Twelve freshly enucleated porcine eyes were measured with ASOCT at baseline, at the beginning of the procedure and at its conclusion to determine the anterior chamber depth (ACD) and the nasal angle in degrees. The right and left eye of pairs were randomly assigned 24 to an active dual blade goniectome (aDBG) and a passive dual blade goniectome (pDBG) group, 25 respectively. The aDBG had an irrigation and aspiration port while the pDBG required surgery 26 under viscoelastic. We performed the procedures using our MIGS training system with a 27 standard, motorized ophthalmic operating microscope. We estimated outflow by obtaining 28 canalograms with fluorescent spheres.

Results: In aDBG, the nasal angle remained wide open during the procedure at above 90° and 30 did not change towards the end (100±10%, p=0.9). In contrast, in pDBG, ACD decreased by 31 51±19% to 21% below baseline (p<0.01) while the angle progressively narrowed by 40±12% 32 (p<0.001). Canalograms showed a similar extent of access to the outflow tract with the aDBG 33 and the pDBG (p=0.513). The average increase for the aDBG in the superonasal and inferonasal 34 quadrants was between 27 to 31% and for the pDBG between 15 to 18%.

Conclusion: ASOCT demonstrated that active irrigation and aspiration improved anterior 36 chamber maintenance and ease of handling with the aDBG in this MIGS training model. The 37 immediate postoperative outflow was equally good with both devices.