Microstents, Cataract Surgery Showing Promise in Glaucoma

SAN FRANCISCO, California — A new reimbursable surgical intervention — microinvasive glaucoma surgery — can lead to long-lasting control of intraocular pressure in many patients with mild to moderate open-angle glaucoma.

"This is a huge development with a lot of therapeutic potential. It reduces or ends the need for medications," ophthalmologist Stephen Obstbaum, MD, from Lenox Hill Hospital in New York City, told Medscape Medical News.

Addressing glaucoma at the same time as cataract surgery can benefit the 90% of open-angle glaucoma patients who have both cataract and glaucoma, according to other leading ophthalmologists who spoke about the topic here at the American Society of Cataract and Refractive Surgery (ASCRS) 2013 Symposium.

In this surgery, microstents are implanted in the eye, where they reduce intraocular pressure by increasing aqueous outflow.

In the United States, the first and only implant available is iStent (Glaukos), a 1-mm, L-shaped tube made from heparin-coated implantable-grade titanium. The surgeon places the iStent into Schlemm's canal using the same clear corneal microincision through which the intraocular lens passed.

Two other drainage devices are currently undergoing clinical testing, but are not yet approved for use by the US Food and Drug Administration.

The growing popularity of microinvasive glaucoma surgery stems in part from its increasing accessibility. As of February 1, all Medicare regional carriers accept implantation of ab interno drainage devices as a reimbursable procedure, noted outgoing ASCRS president David Chang, MD, from Los Altos, California.

This is a huge development with a lot of therapeutic potential.

He explained that when an ab interno aqueous drainage device is implanted concurrent with cataract removal and intraocular lens placement, the additional glaucoma-related surgeon fees can bring the surgeon's total reimbursement for the case to a level that is nearly twice that of a solo cataract procedure. This is encouraging financial news for ophthalmologists, who have had to deal with a number of Medicare cataract fee cuts in recent years.

In his presentation to a ballroom full of surgeons eager to avoid errors when billing for this new source of revenue, Dr. Chang estimated that the surgeon's total reimbursement for a combined case would be $1234, compared with $667 for the cataract procedure alone. The facility fee at an ambulatory surgery center would increase from $971 to $2156, he added.

After 2 years of follow-up, the US iStent Study Group determined that implanting the device concurrent with cataract surgery is a low-risk, effective way to push intraocular pressure to 21 mm Hg or below, and keep it there (Ophthalmology. 2011;118:459-467).

At 1 year, 66% of the eyes treated with combined surgery had achieved a reduction in intraocular pressure of at least 20% without medication, compared with 48% of the eyes treated with cataract surgery only (P = .003)

It has been reported that after combined surgery, the decrease in intraocular pressure persists for as long as 5 years, said Iqbal Ahmed, MD, from the University of Toronto, in Ontario, Canada.

Dr. Ahmed urged comprehensive ophthalmologists to not be intimidated while learning the intricacies of the delicate implant surgery.

Lisa Arbisser, MD, a cataract and anterior segment surgeon in a large group practice in Iowa, Illinois, said she agrees. "This is well within the purview of the general ophthalmologist."

Dr. Arbisser, who is also an adjunct associate professor of ophthalmology at the University of Utah Moran Eye Center in Salt Lake City, told Medscape Mediacl News that she has been "overwhelmingly impressed" with the outcomes of her initial microstent implants.

"I haven't seen any hyphemas; I haven't seen any complication whatsoever," she said. "And for the first time, we get to use the patient's own natural drainage system. This is important because the aqueous is there to bathe and nourish the eye."

Dr. Ahmed explained that microinvasive glaucoma surgery has caused a "complete turnaround" in the treatment recommendations he makes when medical therapy for glaucoma fails. The number of trabeculectomies has fallen by 90%, he said. "We're having trouble training fellows and residents because of this.... Microinvasive glaucoma surgery has completely changed how we look at patients," he said.

The long-lasting suppression of intraocular pressure with this low-risk surgery suggests that microinvasive glaucoma surgery devices will move the ophthalmic profession toward a new paradigm for managing patients with mild to moderate open-angle glaucoma, said Kerry Solomon, MD, a refractive and cataract surgeon from Mount Pleasant, South Carolina.

"I think this is where comprehensive ophthalmologists are going to move. Microinvasive glaucoma surgery presents an opportunity for them to leverage their surgical skills for the benefit of patients," he said.

"In the future, I think we'll see a paradigm shift in glaucoma treatment, Dr. Solomon predicted, "in which the care of patients with mild to moderate glaucoma will stay with the comprehensive ophthalmologist."

Funding for some of the talks referenced in this article came from ophthalmic device companies, including microinvasive glaucoma surgery drainage device makers Glaukos, Ivantis, and Transcend Medical. Dr. Ahmed reports received funding for research, consulting, and/or speaking on behalf of 19 ophthalmic companies, including Glaukos, Ivantis, and Transcend Medical. Dr. Chang reports receiving funding from Abbott Medical Optics, Clarity, LensAR, Transcend Medical, Allergan, and Glaukos; being an equity owner in Calhoun Vision, Clarity, ICON bioscience, LensAR, PowerVision, Revital Vision, Transcend Medical, and Versant Ventures; and holding patents on or receiving royalties from Eyemaginations and Slack. Dr. Obstbaum has disclosed no relevant financial relationships. Dr. Solomon reports received consulting fees and/or research grants from Glaukos, Abbott Medical Optics, Alcon, Allergan, Aquesys, Bausch + Lomb, and QLT; and having investment interests in Aquesys, Glaukos, and QLT.

American Society of Cataract and Refractive Surgery (ASCRS) 2013 Symposium. Presented April 21, 2013.