Study finds glaucoma drainage device implantation has more adverse outcomes

The risk for adverse outcomes after incisional glaucoma surgery appears higher after glaucoma drainage device implantation than after primary trabeculectomy surgery or trabeculectomy with scarring, according to a large multicenter study of Medicare beneficiaries.

"The use of [glaucoma drainage devices] and [trabeculectomy with scarring] are innovations in the last 30 years that have allowed many patients to undergo sight-saving surgery that they would not have had before their use, " the study authors said in the July issue of Ophthalmology. "As such, the rates of adverse consequences seen in the literature should be reviewed with this in mind."

To determine the rates of adverse outcomes after glaucoma surgery, Joshua D. Stein, MD, MS, and colleagues evaluated the claims records of 14,491 Medicare beneficiaries with glaucoma who had undergone primary trabeculectomy, trabeculectomy with scarring or glaucoma drainage device implantation between 1994 and 2003. Specifically, 9,719 of these beneficiaries received primary trabeculectomy, 3,374 received trabeculectomy with scarring and 1,398 received a glaucoma drainage device.

All patients were aged 68 years or older at baseline and were followed up for 6 years or until censored. Observations were censored if a patient died, left Medicare fee-for-service for a Medicare risk plan for more than 6 months, moved outside the United States during a calendar year or received another incisional glaucoma procedure.

The researchers found that beneficiaries in the glaucoma drainage device group were more likely to have had a prior claim for a severe adverse outcome (P < .001) and a less severe adverse outcome (P < .001) during the 3 years before receiving incisional glaucoma surgery than patients in the primary trabeculectomy and trabeculectomy with scarring groups.

At 1-year follow-up, the researchers found that rates of severe adverse outcomes — including retinal detachment, endophthalmitis and suprachoroidal hemorrhage — were higher among beneficiaries in the glaucoma drainage device group (2%) than in the primary trabeculectomy group (0.6%) and trabeculectomy with scarring group (1.3%), according to the study.

"Controlling for prior adverse outcomes to the surgery and demographic factors in Cox proportional analysis, differences were often reduced, but generally remained statistically and clinically significant," the authors said.

Rates of severe outcomes, less severe outcomes — including choroidal detachment, corneal edema and hypotony — as well as low vision or blindness were higher for patients who had undergone glaucoma drainage device implantation than in patients who had undergone primary trabeculectomy or trabeculectomy with scarring.

However, reoperation rates were higher for trabeculectomy with scarring than glaucoma drainage device implantation at all time intervals, the study said.