Abstract and Introduction
Abstract
Purpose: To describe the population at risk of having a severe bleb leak needing a surgical repair in the operating room and to study risk factors associated with severe bleb leak.
Patients and Methods: In this case-control study, 17 cases were enrolled and paired with 51 controls. We studied all patients having a surgical revision in our center for a severe bleb leak between January 1 and December 31, 2008. Three controls were paired to each case based on their surgery date. We then analyzed risk factors related to the patient, the intervention, and the postoperative follow-up.
Results: Younger age was the only statistically significant risk factor for a severe bleb leak in our study. The odds of a severe bleb leak decreased as the age increased (P=0.0029). In comparing the risk for a severe bleb leak in younger (below 55 y) versus patients aged 75 years or older, the odds ratio was 21.0. There were no statistically significant differences between cases and controls with respect to: type of glaucoma, number or types of previous ocular surgeries, number of preoperative topical medications, localization of the leak, localization of the wound (fornix or limbus-based), or the intraocular pressure on day 1 postoperative.
Conclusions: Younger age at the time of trabeculectomy may be a risk factor for severe bleb leak. A trend was observed in which the patients under the age of 55 years were at greater risk for a severe bleb leak.
Introduction
Despite the emergence of new surgical techniques for the treatment of glaucoma, trabeculectomy has remained the gold standard since the late 1960s. The procedure has evolved since then, especially with the introduction of antimetabolites.
The use of antimetabolite agents such as mitomycin-C (MMC) and 5-fluorouracil (5-FU) in glaucoma filtering surgeries has greatly improved outcomes and is now common practice in most Canadian centers. However, it is known that these agents increase the risks of hypotony, late bleb leaks, and endophtalmitis. Bleb leaks may occur early in the days following the surgery or even years later. The rate of these bleb leaks varies greatly between reports and is dependent on the length of the follow-up interval. Studies suggested that the rate of early bleb leak, occurring within 1 month of the surgery, is between 6% and 59%. Studies suggested that the reported incidence of late bleb leaks ranged from 2.9% to 24.6%, during a mean follow-up period of 36.5 months.
With the use of antimetabolites, patients are now more carefully examined for leaks. Other than the use of antimetabolites, there is very little information about risk factors for bleb leaks. One review study identified the following risk factors for early bleb leak:
Inferior location of conjunctival incision,
One-layer closure,
A history of ocular inflammatory disease, and,
Older age at the time of surgery.
Surgical approach also differentiated risk. A limbus-based procedure in contrast to a fornix-based procedure is a risk factor for leaks. Recently, Solus et al found limbus-based procedures were complicated by late bleb leaks, that is, significantly later than fornix-based procedures.
In addition to the actual risk factors associated with surgery, postoperative manipulations in the office may also increase the risk of bleb leak. Surgeons often do suture lysis, needlings, or subconjunctival injections of antimetabolites to help reduce intraocular pressure or reduce the local inflammation. Each of these maneuvers may weaken the conjunctiva and hence increase the rate of bleb leaks. The impact of postoperative manipulations has not been extensively studied. One study showed no increase in bleb leaks within 1 month of the surgery, but little is known about late leaks associated with these postoperative manipulations.
At our center, most leaks do not require repair in the operating room and can be managed in the office. Only persistent and severe leaks require repair in the operating room. The overall annual incidence of severe bleb leaks in our center is about 8.5%. This retrospective study was designed to describe the population at risk of having a severe bleb leak following a trabeculectomy, even years after initial surgery. We defined a severe bleb leak as a bleb leak requiring surgical repair in the operating room, because of few patients having severe bleb leaks in our center, we explored both early and severe bleb leaks.