Long-Term Success of Trabeculectomy May Be High

Joe Barber Jr, PhD

April 17, 2012

April 17, 2012 — The performance of trabeculectomy over a 20-year period indicates that this procedure is adequate for controlling intraocular pressure, according to the findings of a retrospective cohort study.

John Landers, PhD, from Addenbrooke's Hospital in Cambridge, United Kingdom, and colleagues published their findings in the April issue of Ophthalmology.

No previous study has evaluated the long-term efficacy of trabeculectomy in controlling intraocular pressure. "Our paper is the first to follow several hundred patients over this length of time and express outcome in terms of complete and qualified success, and blindness," Dr. Landers told Medscape Medical News by email. "Additionally, this is the first study to assess this many risk factors within the same cohort."

"Although other studies have shown a number of these outcomes separately, none have assessed them simultaneously."

Trabeculectomy Effectively Reduces Intraocular Pressure

Among 330 trabeculectomies performed in a total of 234 eligible patients, approximately 60% of surgeries were classified as complete successes, as indicated by a reduction in the intraocular pressure to less than 21 mmHg for high-tension glaucoma or a greater than 20% reduction in intraocular pressure for normal-tension glaucoma without the need for additional medication, after 20 years of follow-up.

Among the surgeries that failed the definition of complete success, failure was associated with age (hazard ratio [HR] for age ≥80 years vs <40 years, 0.02; 95% confidence interval [CI], 0.002 - 0.2; P < .0001), mean defect at diagnosis (HR for mean defect ≤ −15.00 vs. > −15.00, 10.9; 95% CI, 1.8 - 66.3; P < .01), type of glaucoma (HR for uveitic glaucoma vs primary open-angle glaucoma or normal-tension glaucoma, 12.1; 95% CI, 3.7 - 39.7; P < .0001), previous surgery (HR for intracapsular cataract extraction vs no surgery, 49.0; 95% CI, 11.5 - 209.3; P < .0001); intraocular pressure at diagnosis (HR for ≥40 mmHg vs < 25 mmHg, 8.8; 95% CI, 1.8 - 44.3; P < .01), and number of preoperative topical medications (HR for ≥2 vs 0 to 1 medications, 4.2; 95% CI, 1.9 - 9.3; P < .0001). In a multivariate analysis that included the aforementioned significant variables, only age, number of preoperative medications, and mean defect at diagnosis remained significantly associated with failure.

In addition, approximately 90% of surgeries were classified as qualified successes, as indicated by a reduction in the intraocular pressure to less than 21 mmHg for high-tension glaucoma or a greater than 20% reduction in intraocular pressure for normal-tension glaucoma with the requirement of additional medication, after 20 years of follow-up.

Patient Characteristics and Study Limitations

The authors identified patients who underwent trabeculectomy at Addenbrooke's Hospital between January 1, 1988, and December 3, 1990. The authors included patients who underwent trabeculectomy, phacotrabeculectomy, or redo-trabeculectomy and excluded patients with missing case notes.

The 234 included patients were predominately white, with an average age (±SD) of 65 ± 16 years, and men and women were approximately equally represented (116 women and 118 men). Only 70 patients (30%) were followed for the entire 20-year period.

The study was limited by its retrospective nature. In addition, only 30% of the patients were followed for the entire 20-year study period.

Findings Support the Long-Term Efficacy of Trabeculectomy

Dr. Landers indicated that the findings signify that trabeculectomy should remain an operation of choice for controlling intraoperative pressure. "The trabeculectomy operation has been around now for over 40 years," Dr. Landers told Medscape Medical News by email. "Now, in a time when many clinicians are trying to develop procedures that they say are better than what has been done previously, it is important to realise that what we are currently doing works very well, and as such, it should not be simply disregarded unless a newer therapy can exceed these results."

Keith Barton, MD, FRCP, FRCS, from Moorsfield Eye Hospital in London, United Kingdom, agreed that the findings support the continued use of trabeculectomy. "The results in terms of success rates are impressive given that no adjunctive anti-proliferative agents were used," Dr. Barton told Medscape Medical News by email. "It would seem likely that the high level of success is related to the general case mix in the study, and certainly the finding that patients taking 2 or more preoperative topical medications, uveitics, eyes that had previous surgery, and those with a high IOP or advanced glaucoma at the time of diagnosis all had an elevated risk of failure, is in keeping with expectations." 

The study authors have disclosed no relevant financial relationships. Dr. Barton has received honoraria from Allergan and Pfizer and served in an advisory and/or consulting role with Glaukos, Alcon, Merck, Kowa, Amakem, Thea, Aquesys, Ivantis, and Refocus. He has also received grants from AMO, New World Medical, Alcon, Merck, Allergan, and Refocus, and he owns stocks in Aquesys and Opthalmic Implants (PTE) Ltd.

Ophthalmology. 2012;119:694-702. Abstract

processing....