Intravitreal Bevacizumab Linked to Improved Surgical Success after Trabeculectomy

John A. Landers

Credit: Advanced Glaucoma and Cataract Surgery

A single dose of adjuvant intravitreal bevacizumab (Avastin) may improve postoperative outcomes in patients undergoing trabeculectomy with mitomycin-C (MMC) for progressing glaucoma, according to new research.¹

Trials results indicated the anti-vascular endothelial growth factor (VEGF) medication was also associated with a significant reduction in the need for additional medication and surgery to achieve target intraocular pressure (IOP) in this patient population.

“This is the first paper to be able to demonstrate a positive effect of bevacizumab on the outcomes of trabeculectomy surgery,” wrote the investigative team, led by associate professor John A. Landers, MBBS MPH PhD at the department of ophthalmology, Flinders University of South Australia. “Previous papers examining the use of intraoperative anti-VEGF during trabeculectomy surgery in addition to MMC have found no effect on survival time.”

A mainstay of surgical glaucoma management, trabeculectomy surgery has changed little in the past 5 decades. Currently, trabeculectomy with MMC represents the gold-standard surgical approach to medically refractory glaucoma. However, despite improvements in surgical outcomes, a proportion of patients reportedly fail each year following surgery.²

Landers and colleagues suggested that a single adjunctive intraoperative intravitreal bevacizumab injection during trabeculectomy may inhibit the fibroproliferative phase of wound healing, reduce tenons, and conjunctival thickening in the bleb, ultimately leading to improved outcomes.

The team designed a study to investigate the effect of an adjunctive intraoperative intravitreal bevacizumab injection on trabeculectomy bleb function and morphology during the first postoperative 12 months. The study, a prospective, randomized controlled double-blinded trial design recruited patients classified as having glaucoma requiring trabeculectomy surgery from a single ophthalmic referral center. Patients in the study were randomized to intravitreal bevacizumab treatment or to placebo.

Treatment success was defined as a “complete success” when IOP remained less than a predefined target IOP without the requirement of optical medication, or as a “qualified success” when topical medications were required to meet the predefined target IOP threshold. Further secondary outcomes included the need for subsequent IOP-lowering interventions and structural parameters associated with bleb function.

A total of 131 patients were recruited for this study between July 2016 - September 2018 and randomized to bevacizumab (n = 65) or placebo (n = 66). Demographic factors did not differ between study groups, but a higher proportion of those randomized to bevacizumab underwent phacoemulsification cataract surgery at the time of trabeculectomy (33.8% vs. 18.2%; P = .041). Overall, a total of 128 patients completed the 12-month follow-up (98%).

At 12 months, investigators found the proportion of patients failing to meet complete success criteria was lower in the bevacizumab group compared to placebo (6% vs. 17%; P = .015). The proportion of patients failing to meet the criteria for qualified success was additionally lower in the bevacizumab group in further analysis (2% vs. 10%; P = .033).

The required numbers of bleb needlings were nominally higher at all time points, but the difference was only significant only at the 1-month time point (P = .032). In the control group, the requirement for topical therapy was statistically significant from 6 months onward (6 months: P = .047; 12 months: P = .047).

Blebs in the bevacizumab group were larger in central extent (P <.001), total extent (P <.01), and height (P <.001) at 1 month. Additionally, vessel inflammation was lower in the central bleb (P <.0001), peripheral bleb (P <.0001), and non-bleb conjunctiva (P <.0001) at the 1-month time point in the bevacizumab group. Investigators observed no differences in the incidence of hypotonous maculopathy (P = .65) and no differences in the requirement for surgery to manage hypotony (P = .40).

The investigative team noted the short follow-up time served as a limitation for the study, as adverse surgical outcomes may occur many years postoperatively. However, evidence suggests most trabeculectomy failures occur in the first 12 months, so the study encompassed this critical period.

“Future work should seek to replicate these results and investigate which subgroups may benefit most from this intervention,” investigators wrote.

References

1. Landers JA, Mullany S, Craig JE. Intravitreal bevacizumab improves trabeculectomy survival at 12 months: the bevacizumab in trabeculectomy study-a randomised clinical trial [published online ahead of print, 2023 Aug 4]. Br J Ophthalmol. 2023;bjo-2023-323526. doi:10.1136/bjo-2023-323526
2. Rodriguez-Una I, Azuara-Blanco A, King AJ. Survey of glaucoma surgical preferences and post-operative care in the United Kingdom. Clin Exp Ophthalmol 2017;45:232–40.