This article is more than 5 years old. Information may no longer be current.
Bevacizumab may enhance IOP-lowering outcomes in deep sclerectomy
Study authors were surprised that IOP was comparable in eyes that received bevacizumab or MMC.
Click Here to Manage Email Alerts
As an augmentation agent for primary deep sclerectomy, subconjunctival bevacizumab may enhance the IOP-lowering effects of the procedure without the bleb complications that can accompany surgery with mitomycin C, according to a study.
The retrospective, comparative case-control study analyzed use of MMC vs. Avastin (bevacizumab, Genentech) as an intraoperative adjuvant during deep sclerectomy in 75 eyes.
Nitin Anand
“Our motivation was to find a safer way of inhibiting wound healing after glaucoma surgery,” principal investigator Nitin Anand, MD (Ophth), FRCS, FRCOphth, said. At the time of the study, Anand was a consultant ophthalmic surgeon and glaucoma specialist at Huddersfield Royal Infirmary in the United Kingdom. “Bevacizumab has been injected safely into the vitreous since the early 2000s and has been shown to have no effect on the corneal endothelium, unlike intravitreal 5-fluorouracil and mitomycin C.”
Early studies
Rabbit studies suggest that bevacizumab has a strong inhibitory effect on subconjunctival fibroblasts.
“Preliminary reports of it use with trabeculectomy also show that it is effective and safe,” Anand told Ocular Surgery News. Before starting the current study, Anand and colleagues had injected bevacizumab for more than 3 years in eyes with neovascular glaucoma, for which they observed dramatically less inflamed eyes that responded better to trabeculectomy and tube surgery.
Anand said the problem with using MMC for deep sclerectomy is that some eyes will develop hypotony, with IOP less than 6 mm Hg, in the long term.
Figure 1. The subconjunctival bleb after deep sclerectomy with bevacizumab at 1 week (a). Note the fine caliber of conjunctival vessels. The caliber remained similar at 5 months (b). IOP was 12 mm Hg at 4 years after surgery.
Images:Anand N
Figure 2. Subconjunctival bleb after deep sclerectomy with bevacizumab at 5 weeks (a), 6 months (b) and 2 years (c). Note the remarkable paucity and narrow-caliber conjunctival blood vessels throughout. IOP was 12 mm Hg at 2 years and 16 mm Hg at 4 years after surgery.
“This happens when laser goniopuncture and needle revision are performed to further lower the IOP after deep sclerectomy,” he said.
The study, which appeared in the Journal of Glaucoma, treated 32 eyes with MMC applied before scleral dissection and 43 eyes with bevacizumab injected at the end of surgery. During the first 2 years of follow-up, the mean IOP in both groups ranged between approximately 14 mm Hg and 16 mm Hg.
“There were no differences noted in the number of postoperative procedures, laser goniopuncture or glaucoma medications after surgery,” Anand said. Moreover, only two eyes from each group were still on glaucoma medications at last follow-up (an average of 33.3 months for the bevacizumab group and 35 months for the MMC group).
The study found that the 2-year probability of maintaining an IOP of less than 19 mm Hg and a 20% drop from baseline without medications was “impressive, around 80% overall,” Anand said.
Similar results
Although eyes that received bevacizumab fared slightly better in the survival analyses, the difference was not significant. The safety results of the two adjunct therapies were equally similar.
“There were no differences in complications and bleb morphology observed between MMC and bevacizumab,” Anand said, noting that early complications were minor and rarely lasted beyond 2 weeks.
The study authors were surprised that IOP was comparable in both groups.
“We expected eyes with bevacizumab to require more medications and laser goniopuncture,” Anand said.
The authors also expected a high rate of complications with MMC.
“The use of MMC is associated with a high incidence of bleb avascularity,” Anand said. “Avascular blebs are prone to leak and become infected. Surprisingly, the incidence was much lower (only one eye in each group had cystic areas develop within blebs) than we have reported in a previous application. This may be related to improvements in the technique of MMC application.”
Bevacizumab is an effective and safe agent because the inhibitory effect of the drug is reversible.
“It inhibits vascular endothelium and fibroblasts for 3 to 6 weeks after a subconjunctival injection. This is the critical period for bleb formation,” Anand said. “Bevacizumab also has no major side effect on the anterior chamber structures. In fact, Ingeborg Stalmans, MD, PhD’s, group from Belgium has injected the drug into the anterior chamber during trabeculectomy.”
Despite comparable outcomes for bevacizumab and MMC, “recent comparative studies with trabeculectomy unfortunately have failed to show an advantage of bevacizumab over MMC. IOPs were higher after bevacizumab use,” Anand said. Still, after deep sclerectomy, “inflammation in the anterior chamber is less, so perhaps a less potent but safer agent like bevacizumab may be useful. However, for high-risk eyes, MMC will remain the agent of choice.”
Anand encouraged surgeons to consider deep sclerectomy instead of trabeculectomy.
“It is as effective in low-risk eyes,” he said. “Many glaucoma surgeons in the U.K. and other parts of Europe now use deep sclerectomy as the procedure of choice for open-angle glaucoma. And in my hands, it takes less time to perform than a trabeculectomy, as there is no need to suture the scleral flap fastidiously. The trabeculo-Descemet’s membrane window offers enough resistance to ensure that the anterior chamber remains deep.” – by Bob Kronemyer