Overcoming resistance of making glaucoma a surgical disease

The glaucoma treatment paradigm has always been drops first, laser second, and surgery only as a last resort, according to Reay H. Brown, MD.

“The reasons for the resistance to surgery have been based on concerns that it is too risky, doesn’t work, and has too many scary complication,” said Dr. Brown, private practice, Atlanta. But the hard reality is medical therapy also has many problems.”

The Charles D. Kelman, MD, Innovator’s Lecture and Medal at the 2017 ASCRS-ASOA Symposium and Congress recognized Dr. Brown for his innovations in glaucoma surgery and their influence on the development of microinvasive glaucoma surgery (MIGS).

Delivering his lecture “Overcoming Resistance: Making Glaucoma a Surgical Disease,” Dr. Brown explained the title had a dual meaning because it refers to overcoming resistance to aqueous outflow and resistance to using surgery to treat glaucoma.

Series of starts and stops

Dr. Brown has been an innovator in glaucoma surgery for more than three decades and has developed several devices that never achieved commercial success.

He said, however, that he hopes his work has contributed to the exponential growth in glaucoma surgery that is being driven by MIGS.

Dr. Brown’s belief that glaucoma should be a surgical disease took root back when he was resident at Wilmer Eye Institute in 1979. His first innovation toward achieving that goal was a glaucoma mechanical trephine (the “trabecuphine”) he developed from a vitrectomy cutter for performing an internal filtering procedure.

“The concept seemed simple, but it was too far ahead of its time,” Dr. Brown said.

As the project came to an end, the era of 5-fluorouracil and mitomycin-C for modifying conjunctival wound healing began. Unable to accept that blebs were going to be key to glaucoma surgery, Dr. Brown continued on his path of innovation and developed the glaucoma tack, a device for draining aqueous through the cornea in a procedure that did not require a conjunctival incision.

“The concept was to make glaucoma a microfluidics problem and not a conjunctival wound healing problem,” he said.

The idea for his “glaucoma faucet” however was rejected by two companies he approached for support.

Back in 1995, Dr. Brown and his wife, Mary Lynch, MD, successfully developed a MIGS solution for primary congenital glaucoma-the 360° suture trabeculectomy. Still, he was anxious to find a surgical solution for adult OAG. Influenced by work done by by Robert Stegmann, MD, Dr. Brown and Dr. Lynch aimed to develop a tube connecting Schlemms canal directly to the anterior chamber. Thus, the EyePass Glaucoma Implant was introduced in 1999.

This first trabecular bypass device also encountered challenges to success. Although it eventually entered clinical trials, the sponsor ended the project in 2006, during the final FDA study, due to financial issues.

“Along the way, we developed fundamental patents for trabecular bypass, and we now have 16 years of follow-up on 40 patients showing it was a very safe and stable device,” Dr. Brown said.

Innovation in the modern era

Dr. Brown identified 2008 as the year modern glaucoma surgery began, and the initiating event was a paper reporting that cataract surgery lowers IOP.

“Cataract surgery has been critical to the development of MIGS,” Dr. Brown said.

Although three glaucoma devices were approved in the last 5 years by the FDA and several other approvals are anticipated in the next few years, Dr. Brown believes that the idea that glaucoma should be a surgical disease has not yet come to fruition.

“I said glaucoma should be a surgical disease, but only when we have a safe and effective procedure,” he explained.

Although the safety part of the equation has been met, the IOP-lowering effect from the MIGS procedure itself is still modest.

Considering the explanation, Dr. Brown determined that the IOP-lowering effect of MIGS tubes depends on passive flow.

“That may not be enough,” he said.

To achieve active flow, Dr. Brown is now working with researchers at Georgia Tech to create a pump that uses magnetism to drive artificial pseudocilia. He believes this technology could be used with all MIGS devices.

Concluding his talk, Dr. Brown reflected on the resistance that phacoemulsification encountered when it was first introduced by Dr. Kelman.

“Dr. Kelman is still our inspiration,” Dr. Brown said. “He led the small-incision revolution in cataract surgery and really solved the problem.”

“MIGS development has been more of a team sport and the problem of making glaucoma a surgical disease is definitely not solved yet,” he said.”We need more innovation, but one of the finest things about MIGS is that it gives us hope for the future that one day we will solve the problem of making glaucoma a surgical disease.”