Bleb leaks can occur early or late following glaucoma filtration surgeries, develop with or without infection, and develop more frequently in cases in which an antimetabolite is used.
Chicago-Bleb leaks can occur early (within 3 postoperative months) or late (after 3 months postoperatively) following filtration surgeries and develop with or without infection. Bleb leaks develop more frequently in cases in which an antimetabolite, such as mitomycin C (MMC) or 5-fluorouracil (5-FU), is used. Gloria Fleming, MD, addressed ways to avoid and manage this complication during Glaucoma Subspecialty Day at the American Academy of Ophthalmology annual meeting.
Most bleb leaks are straightforward, and the patients present with tearing, blurred vision, and nonspecific pain or discomfort; however, in other cases, the patients may be asymptomatic, the IOP might be low or normal, the bleb low or flat, surrounding conjunctival injection can be present, the anterior chamber can be normal to shallow, and the patient can have a positive Seidel test, Dr. Fleming pointed out. She is assistant professor of ophthalmology, Havener Eye Institute, Ohio State University, Columbus.
“Early-onset bleb leaks, which occur more frequently after fornix-based, rather than limbal-based, trabeculectomy, usually are related to an aspect of a surgeon’s surgical technique. They are often caused by wound dehiscence, a conjunctival button-hole defect, or a suture track defect,” she said.
A number of management options are possible, such as observation, reduction of aqueous outflow, and use of topical antibiotics or protective eyewear, among others. With an early-onset leak, the goals are to preserve the bleb architecture and function and avoid bleb failure, Dr. Fleming emphasized.
“Late-onset bleb leaks are a challenge,” she said. Many patients are symptomatic, so the true incidence is hard to determine. The incidence of late-onset bleb leaks increases with time; 5 years postoperatively, the probability of a bleb leak after trabeculectomy in which MMC is used is about 20%.
The main risk factor for development of a late-onset bleb leak is the use of antimetabolites intraoperatively, i.e., bleb leaks develop three times more often in cases in which MMC is used compared with 5-FU. Other factors that predispose to development of late-onset bleb leaks are avascular, thin-walled, cystic blebs, “ring of steel” fibrosis, and full-thickness procedures. Hypotony is a complication of late-onset leaks.
Importantly, late-onset bleb leaks set the stage for infections and carry a 26-fold increased risk compared with controls. One infection, blebitis, is more benign than endophthalmitis. Patients with blebitis usually can achieve their baseline visual acuity with resolution. The same is not true of patients with endophthalmitis, which is characterized by virulent organisms with the potential to produce exotoxins and cause serious visual deterioration.
“There is no consensus on management of late-onset bleb leaks, and decisions should be patient-specific based on the character and size of the bleb leak, glaucoma, severity, fellow eye status, the risk of a bleb-related infection, and patient adherence to follow-up care,” Dr. Fleming said.
“We have learned that by modifying our surgical technique, the flap, and the way in which the antimetabolite is applied, we can achieve a different type of bleb, specifically, one that is more diffuse, posterior, and low profile, which will allow us to move away from the high-risk blebs of the past,” she concluded.
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