No Pain, All Gain: On the Cusp of a New Treatment for AMD

Times, they could be a-changin’ for patients with age-related macular degeneration (AMD). A new medical device has moved into phase III clinical trials—the last stage before the Food and Drug Administration (FDA) decides whether to approve it. The results from phase II indicate cause for hope for people currently dependent on receiving injections every four to six weeks for their AMD. In the phase II trial, 80 percent of patients went at least six months before getting another dose of medication, and—the best part—that dose was injected into a refillable device rather than into their eye.

The device, a little longer than a grain of rice, is the Port Delivery System (PDS), an implantable reservoir a surgeon inserts into the patient’s eye. To do so, a surgeon makes an opening in the conjunctiva—the thin membrane covering the white sclera (the wall of the eye)—and folds it back. The surgeon next makes an opening in the sclera, which surrounds the cornea (the clear window through which the colored part of the eye is seen), and inserts the PDS filled with anti-VEGF (vascular endothelial growth factor) medication. The body of the PDS, the reservoir, extends into the vitreous cavity of the eye. The other end has a circular plastic piece, referred to as a flange, that juts out a little wider than the opening the surgeon made, so when the PDS is inserted completely, that piece seals the opening.

Finally, the surgeon unfolds the conjunctiva and sutures it to cover the flange of the PDS, which prevents the access of germs. The medication is slowly released into the vitreous cavity and diffuses into the retina, where it binds VEGF and prevents the growth of leaky blood vessels that cause vision loss.

The center of the flange has a septum, a self-sealing rubber sheet (like the top of a vial of blood), which the doctor can see with magnification but a casual observer cannot. When the patient returns for treatment, the doctor inserts a small needle of anti-VEGF medication through the septum and refills the PDS.

Peter Campochiaro, M.D., Wilmer’s George S. and Dolores D. Eccles Professor of Ophthalmology and Neuroscience, serves as the scientific adviser and principal investigator for the clinical trial. He explains why patients could prefer a refill to an injection. “For a refill, you have to just go through the conjunctiva and then through the septum,” he says. And doctors can numb the conjunctiva effectively. “We’re using a very small needle—38-gauge—so you have to push to get it through the septum. Patients do feel pressure from that, but no pain,” he says. In addition, patients do not feel the device in their eye.

Conversely, with the current treatment of injections, the shot must go through the entire eye wall, not just the conjunctiva. “Why patients feel the injections is that we can numb the conjunctiva, but it’s hard to numb the tissue underneath,” he says.

Patients participating in the phase III trial will have the PDS device, filled with the anti-VEGF medication, surgically inserted. After six months, they will get a refill of medication. “Then three months later the vision will be measured and compared to the control group, which is getting monthly anti-VEGF injections,” says Campochiaro. When researchers have gathered all the data from each patient, they will send it to the FDA, which usually takes six to eight months to evaluate the data. This is an “aggressive” timeline, according to Campochiaro—which is great news for patients eager to see their ophthalmologists fewer than 10 to 12 times a year.