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Although leaking filtering blebs often can be managed with conservative measures, surgery to stop the leak is indicated in some cases. A surgical approach may be indicated especially in certain high-risk eyes, such as those with a history of bleb-related infection. Several surgical techniques may be used to control a leaking bleb effectively.
August, GA-Conservative measures will resolve some leaking filtering blebs, but surgery is indicated in cases where conservative measures are not enough, according to Herbert Fechter, MD, PE, Eye Physicians and Surgeons of Augusta, GA.
"Surgical measures should be considered when conservative measures fail, especially in eyes with a history of bleb-related infection, corneal folds that interfere with vision, a shallow anterior chamber with lens/corneal touch, persistent choroidal diffusion, or hypotony maculopathy," Dr. Fechter said.
Thin, avascular blebs are more likely to leak than thick, diffuse blebs and also pose a higher risk of hypotony and infection, he said.
In other cases, leaks persist despite conservative therapy, and more aggressive measures are necessary.
Dr. Fechter said he recommends three surgical options for leaking blebs: compression sutures, conjunctival advancement, and bleb repair with tube implant.
"I elected to wall off the leaking conjunctiva using a 9-0 nylon compression suture," Dr. Fechter said. "I passed a half-thickness corneal suture at the limbus, draped it over the bleb, and anchored it to the superior episclera. I tied the knot at the limbus, and rotated it into the cornea. I placed a second compression suture to further restrict aqueous flow through the leaking conjunctiva."
The sutures were removed after 2 months and the bleb has remained Seidel negative, he said.
More aggressive approach
Dr. Fechter cited the case of a monocular patient who had a persistent bleb leak despite conservative measures. To treat the hypotony and prevent infection, he performed a bleb revision with conjunctival advancement.
An injection of balanced salt solution helped dissect a plane between Tenon's capsule and the underlying sclera. A 15° blade incised the "ring of steel" that separates healthy conjunctiva from devitalized tissue. Dr. Fechter used blunt scissors (Wescott scissors, multiple manufacturers/distributors) to dissect posteriorly and divide the attachments carefully between Tenon's capsule and the superior rectus muscle.
"Excising the ischemic conjunctiva allows fresh tissue to seal at the limbus and create a non-leaking bleb," Dr. Fechter said. "If necessary, peripheral relaxing incisions can be made to free more conjunctival tissue."
The mobilized conjunctiva was sutured to the limbus using a horizontal mattress and two wing sutures. Postoperatively, the new bleb required aqueous suppressants to keep the IOP in the low teens.
The third surgical option suggested by Dr. Fechter is the implantation of a glaucoma drainage device while repairing the leaking bleb. He said he used this technique effectively for a young patient who had a persistent bleb leak, with a shallow anterior chamber and choroidal effusions, despite conservative therapy.
"The elevated risk of trabeculectomy failure and the patient's desire to avoid long-term eye drop use influenced my decision to implant a drainage device while repairing the leaking bleb," Dr. Fechter said.
For this procedure, he mobilized the superior conjunctiva, implanted the drainage device, and routed the tube supero-nasally. He excised the ischemic epithelium flush with the limbus, to allow better adhesion of the fresh conjunctiva. To prevent postoperative hypotony, he resutured the prior trabeculectomy flap with a 10-0 nylon suture. He secured the fresh conjunctiva to the limbus using a horizontal mattress and two wing sutures.
"The infection risk has been reduced, the vision improved, and the pressure controlled without glaucoma medications," Dr. Fechter said.
Several conservative measures can be used to control a leaking bleb. In cases in which they prove to be inadequate, consider surgical therapies such as compression sutures, conjunctival advancement, or bleb repair with drainage tube implant, Dr. Fechter concluded.