This still image from video shows the Xen Gel Stent...

This still image from video shows the Xen Gel Stent injected into the eye's subconjunctival space through a small, self-sealing corneal incision, using a preloaded injector. Credit: Allergan / via YouTube

Ophthalmologist Dr. Arnold Prywes has fulfilled a mission years in the making — helping a patient with a challenging case of glaucoma by implanting a sight-saving device that he invented in 1991.

Prywes, chief of the glaucoma service at Northwell Health’s hospitals in New Hyde Park and Manhasset, used his invention — a tiny, pressure-relieving stent — in a procedure last month. Twenty-six years of delays caused by numerous obstacles, including a lengthy patent procedure and regulatory demands, prevented its use until now.

The minuscule tube is one of the world’s smallest medical devices. It is permanently implanted into the eyes of people with difficult-to-treat cases of glaucoma and acts as a shunt to drain excess fluid.

“It’s teeny-tiny, about the width of a human hair,” Prywes said, trying to convey the stent’s exceptionally small size — about 6 millimeters, or 0.23622 of an inch, in length.

“We have to do this under a surgical microscope, we call it an operating microscope,” said Prywes, who has private ophthalmology practices in Lake Success and Bethpage.

Glaucoma is a serious eye disorder and the second-leading cause of blindness, after cataracts. But unlike the latter, glaucoma’s vision loss is irreversible. It is characterized by excess fluid pressure in the eye, which damages the optic nerve. Most cases are treated with pressure-controlling eye drops or laser therapy. For some people, however, those methods are not enough.

Sometimes called hypertension of the eye, glaucoma, like high blood pressure, is a silent affliction. The Glaucoma Research Foundation estimates that 3 million people in the United States are affected by the disorder, but only half are aware of it.

Aging, family history, use of steroid medications, nearsightedness, farsightedness, and being of African-American or Latino heritage are among the risk factors for the eye condition, ophthalmologists say.

Prywes designed the device to be implanted in the trabecular meshwork — a labyrinth of cells connected to tiny tubing in the eye that, when healthy, serves as a plumbing system to keep intraocular pressure under control.

He said he became an inventor because glaucoma patients needed a minimally invasive alternative to the widely accepted standard of care.

That standard is a surgical technique known by two names: a trabeculectomy, or the Cairns and Watson procedure, which was developed in 1968. This method of addressing extreme intraocular pressure is not only invasive, it requires tremendous surgical skill because it involves precise dissection of the outer and inner layers of the eye, Prywes said.

However, the surgery in some rare instances can cause pressure in the eye to become too low, which presents an entirely different and equally concerning problem, said Dr. Charles Rothberg, a Patchogue ophthalmologist and president of the Medical Society of the State of New York.

The Cairns and Watson procedure emerged, Rothberg said, because ophthalmologists had long recognized the importance of relieving pressure in intractable cases of glaucoma. But doctors also were well aware of its drawbacks, the most common of which is its long, burdensome postoperative period.

“What Dr. Prywes has done is provide a safer modality,” he added.

Prywes, by starting his journey 26 years ago toward a minimalistic approach, was decades ahead of several similar developments increasingly common in the field, Rothberg said.

In Oceanside, Dr. Richard Nauheim, director of ophthalmology at South Nassau Communities Hospital, called the miniature tube a welcome option.

“The stent is a pathway to release the fluid that is building up in the eye and normalize the pressure, which prevents glaucoma from progressing,” said Nauheim, an assistant professor of ophthalmology at the Zucker School of Medicine, a division of Hofstra University.

He added that treatment for the condition, even when it responds to eye drops, is a lifelong commitment.

Prywes applied for a patent on the stent the year he invented it. But eight years went by before one was approved.

Even then, despite a medical need for a conduit through which the eye’s excess fluid could flow, medical device-makers initially were not ready to embrace it.

In 1999, with his patent in hand, Prywes said he contacted major medical and surgical device companies, all of which turned him down. Entreaties to smaller, ophthalmic instrument makers were fruitless as well.

Not until 2006 did he receive a call from The Innovation Factory in Georgia. That enterprise “finds promising medical technology ideas in their earliest stages, develops them into groundbreaking products, and leads them to market via new companies we launch,” according to the factory’s website.

The Innovation Factory launched AqueSys Inc., a company designed to develop and clinically test the stent.

In 2012, Prywes traveled to the Dominican Republic, where he was able to implant the device in glaucoma patients there. Clinical trials also were begun in Europe, where the little tube was approved in 2014. Canadian medical device regulators approved it in 2015, the same year that pharmaceutical giant Allergan Inc. bought AqueSys for $300 million.

Finally, in November of last year, the U.S. Food and Drug Administration approved Prywes’ device, formally known as the Xen Gel Stent. More time elapsed, however, as he awaited coverage of the $1,500 device by medical insurers.

“We are now waiting for Medicare to pay for the device for our older patients,” Prywes said, referring to one of the largest populations at risk for glaucoma and its complications.

A primer on glaucoma

The term glaucoma refers to a group of disorders that damage the optic nerve, resulting in diminished vision or blindness. With early detection and treatment, vision can be preserved. There is no cure.

An estimated 3 million people in the United States have some form of glaucoma.

The two most common forms are open-angle glaucoma and angle-closure glaucoma. Of the two, open-angle is the most common.

Open-angle glaucoma gets its name from the position — the “angle” — where the iris, or colored portion of the eye, meets the cornea, the eye’s clear outer shield. This angle is usually normal, but the eye’s drainage is slow and the eye’s tiny canals become clogged over time.

Clogging in open-angle glaucoma is painless and without noticeable early symptoms. Blocked drainage causes the internal pressure to mount, which can damage the optic nerve. Peripheral vision loss is a signal of the condition.

Angle-closure glaucoma is typified by fluid at the front of the eye not draining through the angle and leaving the eye.

People with angle-closure glaucoma may have a sudden increase in eye pressure. Symptoms include severe pain and nausea, as well as redness of the eye and blurred vision.

Glaucoma medications come in eyedrop and pill forms. Eyedrops, used regularly, lower eye pressure. Some medicines cause the eye to make less fluid, and others lower pressure by helping fluid drain from the eye.

Sources: National Eye Institute; Dr. Richard Nauheim, South Nassau Communities Hospital; Dr. Charles Rothberg, Patchogue ophthalmologist

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