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Impact of a glaucoma severity index on results of trabectome surgery: Larger pressure reduction in more severe glaucoma

Loewen, RT and Roy, P and Parikh, HA and Dang, Y and Schuman, JS and Loewen, NA (2016) Impact of a glaucoma severity index on results of trabectome surgery: Larger pressure reduction in more severe glaucoma. PLoS ONE, 11 (3).

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Abstract

© 2016 Loewen et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. Purpose: To stratify outcomes of trabectome-mediated ab interno trabeculectomy (AIT) by glaucoma severity using a simple and clinically useful glaucoma index. Based on prior data of trabectome after failed trabeculectomy, we hypothesized that more severe glaucoma might have a relatively more reduced facility compared to mild glaucoma and respond with a larger IOP reduction to trabecular meshwork ablation. Methods: Patients with primary open angle glaucoma who had undergone AIT without any other same session surgery and without any second eye surgery during the following 12 months were analyzed. Eyes of patients that had less than 12 months follow up or were diagnosed with neovascular glaucoma were excluded. A glaucoma index (GI) was created to capture glaucoma severity based on visual field, number of preoperative medications, and preoperative IOP. Visual field (VF) was separated into 3 categories: mild, moderate, and advanced (assigned 1,2, and 3 points, respectively). Preoperative number of medications (meds) was divided into 4 categories: ≤1, 2,3 or ≥4, and assigned with a value of 1 to 4. Baseline IOP (IOP) was divided into 3 categories: <20 mmHg, 20-29 mmHg, and greater than 30 mmHg and assigned with 1 to 3 points. GI was defined as IOP × meds × VF and separated into 4 groups: <6 (Group 1), 6-12 (Group 2), >12-18 (Group 3) and >18 (Group 4). Linear regression was used to determine if there was an association between GI group and IOP reduction after one year or age, gender, race, diagnosis, cup to disc (C/D) ratio, and Shaffer grade. Results: Out of 1340 patients, 843 were included in the analysis. The GI group distribution was GI1 = 164, GI2 = 202, GI3 = 260, and GI4 = 216. Mean IOP reduction after one year was 4.0±5.4, 6.4±5.8, 9.0±7.6,12.0±8.0 mmHg for GI groups 1 to 4, respectively. Linear regression showed that IOP reduction was associated with GI group after adjusting for age, gender, race, diagnosis, cup to disc ratio, and Shaffer grade. Each GI group increase of 1 was associated with incremental IOP reductions of 2.95±0.29 mmHg. Success rate at 12 months was 90%, 77%, 77%, and 71% for GI groups 1 to 4. The log-rank test suggested significant differences between GI groups. Conclusion: A simple glaucoma index, GI, was created to capture glaucoma severity and a relative resistance to treatment. A higher GI was associated with a larger IOP reduction in trabectome surgery. This indicates that there is a role for AIT beyond mild glaucoma and ocular hypertension.


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Details

Item Type: Article
Status: Published
Creators/Authors:
CreatorsEmailPitt UsernameORCID
Loewen, RTrtl13@pitt.eduRTL13
Roy, P
Parikh, HA
Dang, Yyad23@pitt.eduYAD23
Schuman, JSjss28@pitt.eduJSS280000-0002-8885-3766
Loewen, NANAL58@pitt.eduNAL58
Contributors:
ContributionContributors NameEmailPitt UsernameORCID
EditorAcott, Ted S.UNSPECIFIEDUNSPECIFIEDUNSPECIFIED
Date: 1 March 2016
Date Type: Publication
Access Restriction: No restriction; Release the ETD for access worldwide immediately.
Journal or Publication Title: PLoS ONE
Volume: 11
Number: 3
DOI or Unique Handle: 10.1371/journal.pone.0151926
Institution: University of Pittsburgh
Schools and Programs: School of Medicine > Ophthalmology
Refereed: Yes
Date Deposited: 25 Aug 2016 15:42
Last Modified: 04 Feb 2019 15:58
URI: http://d-scholarship.pitt.edu/id/eprint/28281

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