According to Iqbal (“Ike”) K. Ahmed, M.D., a professor of ophthalmology and director of the Glaucoma and Advanced Anterior Surgical (GAASS) Fellowship at the University of Toronto, about 20% of people who have cataract surgery also have glaucoma. For these people, emerging research now suggests that performing glaucoma microstent treatment during cataract surgery is safe and more effective than cataract surgery alone.

What Are Glaucoma Microstents?

A microstent is a tiny tube surgically implanted in the eye’s constricted channels so fluids can move more easily through its natural drainage system and pressure inside the eye can be lowered. 

More specifically, Ahmed explains that microstents are about the size of an eyelash and are implanted in the eye during open-angle glaucoma surgery. Their purpose is to allow aqueous humor, or fluids in the eye, to move more freely through Schlemm’s canal that disposes of the fluid by channeling it to blood vessels. In doing so, intraocular pressure (IOP) can be reduced.

Microstents have become more popular, especially in the U.S., says Ahmed. In particular, Louisiana-based ophthalmologist David Rooney, M.D. points to stent devices like the Hydrus® and iStent for treating less severe open-angle glaucoma in people with significant cataracts.

Better Results After Five Years

At the 2021 annual meeting of the American Academy of Ophthalmology, follow-up results from the HORIZON randomized controlled trial of the Hydrus microstent were presented by Ahmed.

• Five hundred fifty-six patients with primary-angle glaucoma were followed for five years after undergoing either cataract surgery plus Hydrus implantation or surgery alone, with 443 patients remaining in the study after five years.
• At five years, only 2.5% of patients whose eyes were implanted with the Hydrus stent required invasive follow-up glaucoma surgery versus 6.4% of patients with untreated eyes.
• Treated patients were also less likely to need glaucoma medication, with 34% of treated patients requiring continued medication versus 54% of untreated patients.
• Further, treated patients experienced 47% less visual field loss than untreated patients.
• While results were positive, risk of stent-related complications did rise slightly. Stent malpositioning occurred in 1.4% of patients, and peripheral anterior synechiae (PAS) happened more often in stent recipients than with cataract surgery alone.

The findings build on a previous three-year follow-up study, supporting previous research. Rooney explains that a 2020 systematic review showed people with less severe open-angle glaucoma who had Hydrus treatment plus cataract surgery had lower IOP than those having cataract surgery alone.

What It Means for Patients and Providers

Overall, Ahmed says the microstent procedure is “very safe” with small added risk beyond cataract surgery alone, and it is covered by Medicare and most other insurance. Its cost ranges from $1,400-$1,900, depending on one’s location and other factors, but is offset by a reduction in other costs like office visits, medication, and future invasive procedures.

Rooney advises that people with a history of uveitis not have the procedure. He blocks his patients beforehand to avoid unwanted movement during implantation, and he is often able to treat focal synechiae (the most common postoperative complication) with a YAG laser. The Hydrus is his preferred method for treating mild to moderate open-angle glaucoma and significant cataracts.

“In practice, I take my patients off of their antihypertensive drops immediately after Hydrus implantation and monitor whether they still need medication management of their glaucoma, which they usually do not,” said Rooney.

*Dotinga, R. (2021, November 17). Microstent for Cataract Surgery Reduced Need for Glaucoma Meds. MedPage Today. https://www.medpagetoday.com/meetingcoverage/aao/95729