Elsevier

Ophthalmology

Volume 119, Issue 1, January 2012, Pages 36-42
Ophthalmology

Original article
Ab Interno Trabeculectomy Versus Trabeculectomy for Open-Angle Glaucoma

https://doi.org/10.1016/j.ophtha.2011.06.046Get rights and content

Purpose

To compare the effect of ab interno trabeculectomy with trabeculectomy.

Design

Retrospective, cohort study.

Participants

A total of 115 patients who underwent ab interno trabeculectomy (study group) compared with 102 patients who underwent trabeculectomy with intraoperative mitomycin as an initial surgical procedure (trabeculectomy group). Inclusion criteria were open-angle glaucoma, age ≥40 years, and uncontrolled on maximally tolerated medical therapy. Exclusion criterion was concurrent surgery.

Methods

Clinical variables were collected from patient medical records.

Main Outcome Measures

Intraocular pressure (IOP) and Cox proportional hazard ratio (HR) and Kaplan–Meier survival analyses with failure defined as IOP >21 mmHg or less than 20% reduction below baseline on 2 consecutive follow-up visits after 1 month; IOP ≤5 mmHg on 2 consecutive follow-up visits after 1 month; additional glaucoma surgery; or loss of light perception vision. Secondary outcome measures include number of glaucoma medications and occurrence of complications.

Results

Mean follow-up was 27.3 and 25.5 months for the study and trabeculectomy groups, respectively. Intraocular pressure decreased from 28.1±8.6 mmHg at baseline to 15.9±4.5 mmHg (43.5% reduction) at month 24 in the study group, and from 26.3±10.9 mmHg at baseline to 10.2±4.1 mmHg (61.3% reduction) at month 24 in the trabeculectomy group. The success rates at 2 years were 22.4% and 76.1% in the study and trabeculectomy groups, respectively (P<0.001). Younger age (P = 0.037; adjusted HR, 0.98 per year; 95% confidence interval [CI], 0.97–0.99) and lower baseline IOP (P = 0.016; adjusted HR, 0.96 per 1 mmHg; 95% CI, 0.92–0.99) were significant risk factors for failure in the multivariate analysis of the study group. With the exception of hyphema, the occurrence of postoperative complications was more frequent in the trabeculectomy group (P<0.001). More additional glaucoma procedures were performed after ab interno trabeculectomy (43.5%) than after trabeculectomy (10.8%, P<0.001).

Conclusions

Ab interno trabeculectomy has a lower success rate than trabeculectomy.

Financial Disclosure(s)

Proprietary or commercial disclosure may be found after the references.

Section snippets

Materials and Methods

All study procedures were approved by the institutional review board of the Massachusetts Eye and Ear Infirmary and the University of Southern California in adherence with the Declaration of Helsinki and the Health Insurance Portability and Accountability Act. We retrospectively reviewed the medical records of all patients who underwent primary ab interno trabeculectomy, subsequently named the “study group” between February 2006 and September 2009, and trabeculectomy, subsequently named the

Results

A total of 417 patients (417 eyes) met the inclusion criteria. Two hundred patients were excluded for the occurrence of concurrent surgery. Of the 200 eyes that were excluded, 124 were from the study group and 76 were from the trabeculectomy group; 191 had concurrent cataract surgery. A total of 217 patients (217 eyes) were included in this study; 115 cases had ab interno trabeculectomy (study group), and 102 cases had trabeculectomy as an initial surgical procedure for medically uncontrolled

Baseline Characteristics

The baseline demographic and medical characteristics of the patients in each group were equivalent except baseline VA, previous laser trabeculoplasty, and cup-to-disc ratio (Table 1, available at http://aaojournal.org). Baseline VA was better in the study group (0.34±0.40 vs. 0.63±0.82; P=0.001). There were more patients who had previous argon or selective laser trabeculoplasty in the study group (47.8% vs. 30.4%; P = 0.031), and cup-to-disc ratio was larger in the trabeculectomy group

Discussion

Our data demonstrate that both ab interno trabeculectomy and trabeculectomy lower IOP. Trabeculectomy had a greater success rate with lower mean IOP and less need for supplemental antiglaucoma medications at all time points. The results of our trabeculectomy arm were approximately comparable to the literature. In our series, trabeculectomy had success rates of 85.6% and 76.1% at 1 and 2 years, respectively, using modified TVT criteria. The trabeculectomy arm of the TVT study reported success

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Manuscript no. 2010-1387.

Financial Disclosure(s): The author(s) have made the following disclosure(s): Dr. Francis is a consultant for NeoMedix, Inc. The other authors have no proprietary or commercial interest in any materials discussed in this article.

This article contains online-only material. The following should appear online-only: Tables 1, 2, and 7.

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