With modification of filtering procedures, bleb-related problems decrease

PHILADELPHIA — The success of filtering surgery depends on a diffuse bleb with a large surface area, according to a surgeon speaking here at a meeting celebrating the 40th anniversary of the Wills Eye Hospital glaucoma fellowship program.

Peng T. Khaw, PhD, FRCP, FRCS, FRCOphth, said that by enlarging the surface area of the bleb, surgeons can decrease the incidence of bleb-related problems from 20% to none.

"I want to control the flow zones," he said. "It’s the flow zone that gives you cystic blebs that are not diffuse."

To achieve greater control, Mr. Khaw said he modifies his trabeculectomy in a few small ways. He said he opts for fornix-based flaps, employs a small punch (about 500 µm) and introduces infusion similar to that used in phacoemulsification.

Mr. Khaw said the use of antimetabolites must be "judicious" both intraoperatively and postoperatively. He noted that there are other antiscarring agents, such as human monoclonal antibody, that are currently being tested worldwide.

Finally, Mr. Khaw said he uses adjustable, as opposed to releasable, sutures. Suture lysis has a tendency to cause pressure "gymnastics," or large fluctuations in pressure, he said, while suture adjustment accomplishes gradual pressure titration. Forceps with a duck-bill tip allow the surgeon to adjust sutures without tearing the conjunctiva, he said.

"We have much tougher targets than we’ve ever had before," Mr. Khaw said. "There are little things that have helped me considerably in my quest to improve patient – and my own – satisfaction."

Mr. Khaw presented a video of one of his patients who expressed how "amazed" she was that her eye was pain-free after the procedure and that she could easily read and drive a car even at day 1 postop.

"They’re happy; they can even recommend trabeculectomy to some of their friends," Mr. Khaw said.