A new retrospective case-control study evaluated the outcomes of trabeculectomy ab externo with mitomycin C in patients of African ancestry with primary open-angle glaucoma. The analysis focused on surgical success, complication rates, and predictors of surgical failure in a high-risk population.
“[Patients with] African ancestry are disproportionately affected by primary open angle glaucoma (POAG),” wrote lead study author Anusha Mamidipaka, BS, and colleagues in their recent Journal of Glaucoma article. “Black individuals have a higher likelihood of undergoing glaucoma surgery and progressing to severe POAG compared with White individuals … Surgical outcomes are often unpredictable, particularly in the most severely affected African ancestry population. Thus, an investigation into trabeculectomy outcomes and predictors of success in African ancestry individuals is needed,” they stressed.
The study, which was conducted at the University of Pennsylvania, included 63 eyes from 55 self-identified Black patients (African American, African descent, or African Caribbean). Most eyes (77%) had severe glaucoma at the time of surgery.
The follow-up period was a minimum of 12 months postsurgery. Complete success was defined as intraocular pressure (IOP) between 5 and 21 mmHg or at least a 20% reduction from baseline without glaucoma medications. Qualified success was achievement of the same IOP targets, but with additional medications. Failure was defined as inadequate IOP control or a need for additional surgical intervention within 1 year.
Almost half (46%) of the patients achieved complete success, whereas 22.2% of them had qualified success. The procedure failed in 31.8% of patients. With a stricter IOP threshold (less than 15 mmHg), success remained at 46%, but failure increased to 34%.
Mean IOP decreased by 11.9 mmHg (−46.7%) at 1 year (from 25.5 to 13.8 mmHg, P < .001), glaucoma medication use decreased by 73.7%, and eye drop use decreased by 67.1% (both P < .001).
Visual acuity (VA) worsened by 56% (LogMAR +0.17, P < .001), visual field (VF) mean deviation declined by 13.8% (P = .02), and VF index decreased by 18.8% (P = .004).
At 1-year postsurgery, 58.7% of the patients experienced complications. The most common complications were additional surgery (28.6%) such as bleb revision, glaucoma drainage tube implant, and scleral replacement and reinforcement; bleb leak (23.8%); hypotony (23.8%); bleb failure (17.5%); choroidal detachment (17.5%); and cataract (9.8%). There were no cases of blebitis, endophthalmitis, or choroidal hemorrhage.
In a univariate analysis, the researchers discovered that younger age at surgery (P = .01) and positive family history of glaucoma (P = .046) were associated with higher failure rates. They determined from a multivariable analysis (adjusted for age and glaucoma stage) that worse preoperative VA (per 0.1 LogMAR increase) was significantly associated with failure (odds ratio = 0.79, P = .02). Mitomycin C concentration, application method (sponge vs injection), prior surgery, and refractive error were not associated with surgical outcome.
“Racial disparities in high-quality health insurance and access to lower-volume health facilities, paired with other social and economic factors, have been known to contribute to lower surgical success rates, in general, in Black patients,” the study authors wrote. “Biological differences may also affect surgical success, supported by findings of increased fibroblasts and macrophages in conjunctival biopsies following trabeculectomy failure, indicating a more aggressive wound healing response,” they continued.
Among the study’s limitations were its small sample size and single-institution setting that may have limited generalizability. Its retrospective design may have introduced potential bias. Additionally, cataract progression was not systematically recorded, surgical success beyond 1 year was not assessed, and surgical technique and mitomycin C dosing varied across surgeons.
“While trabeculectomy demonstrates positive outcomes, including substantial reductions in IOP and medication, these findings underscore the complexities of trabeculectomy outcomes in African ancestry populations and highlight the need for precision-based approaches to glaucoma management,” the study authors concluded.
No conflicts of interest were disclosed
