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Editors Selection IGR 14-1
Surgical Therapy: Twenty years of trabeculectomy: risk factors and outcomes
Comment by Marc Lieberman on:
48837 A Twenty-Year Follow-up Study of Trabeculectomy: Risk Factors and Outcomes, Landers J; Martin K; Sarkies N et al., Ophthalmology, 2012; 119: 694-702
The senior co-author of this magisterial 20-year overview of the efficacy of trabeculectomy was a primary innovator in 1970 of what has become the fundamental surgical procedure in our glaucoma armamentarium. As might be expected from such a long-term retrospective analysis, this study has circumscribing parameters which constrain the applicability of its findings: e.g., an almost exclusively Caucasian population with mixed types of glaucoma (primary open-angle, angle-closure, uveitic, aphakic, etc.); limbal-flap trabeculectomies without peri-operative anti-metabolites or suture adjustment; only a few medications available as adjunctive therapy; and neither perimetric nor disc criteria for discrimination of glaucoma stages.
Simple categories (per WGA guidelines) were used: 'complete success' (IOP < 21 mmHg without medication), 'qualified success' (IOP < 21 mmHg with medication), and 'functional success' (legal blindness avoided.) Though there was a rapid failure rate evident in the first post-surgical years, the rate slowed and stabilized in all groupings for the remainder of the study. By the end of 20 years, approximately 60% remained successful without further therapy, increasing to 90% by including those using medications as well. By year-10 some 7% had become blind; and a total of 15% blind by year-20 ‐ 'success' and blindness rates comparable to a dozen other studies referenced in their Table 5.
Retrospective data collection was the acknowledged primary limitation of the study. Rigorous attempts to identify systematic bias as a result of data loss revealed that 90% of 'lost' eyes were due to patient deaths; moreover, a Cox proportional hazard analysis assumed all censored patients as failures, leading to 'a conservative estimate of survival'. No details were provided as to adverse events, such as bleb leaks or endophthalmitis. The key risk factors for surgical failure included advanced age, high IOPs, prior surgeries, and type of glaucoma (e.g., uveitis). By and large these suggest that the more severe and prolonged the glaucomatous process, the likelier the probability of trabeculectomy failure.
Surgical outcomes require several years' follow-up to draw realistic conclusions
Contemporary perimetry and OCT studies of the disc/NFL now identify earlier cases of disease, and detect progression or stabilization in ways unknown 40 years ago; thus a finer grain of resolution for the efficacy of our surgery is available to us. Yet this paper's 'longterm view' is a helpful perspective to contextualize many current, intriguing glaucoma surgical innovations, many of which are fueled by commercial pressures unknown a generation ago in ophthalmology.
The 'vilification' of trabeculectomy by some proponents of innovation is simply inappropriate
Whatever procedures lay ahead in our future, the decades' long profile of success that this study reports is a cautionary reminder in two regards. First, surgical outcomes require several years' follow up to draw realistic conclusions; secondly, how the 'vilification' of trabeculectomy by some proponents of innovation is simply inappropriate.
The enormous contribution of this 'simple' filtration procedure - still the only surgical option in most third-world settings, where the risk of glaucomatous blindness is greatest - is indeed worthy of respect
The enormous contribution of this 'simple' filtration procedure ‐ still the only surgical option in most third-world settings, where the risk of glaucomatous blindness is greatest ‐ is indeed worthy of respect
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