• Posted August 11, 2025

Implant Protects Against Vision-Destroying Eye Disease

A newly approved implant appears to slow vision loss from a rare and previously untreatable eye disease, researchers report.

The eye implant, called ENCELTO, gradually releases proteins that protect light-sensing nerve cells against macular telangiectasia (MacTel) type 2, researchers recently reported in the journal NEJM Evidence.

The capsule-sized implant slowed the progression of MacTel in two phase 3 clinical trials involving more than 200 people, researchers said.

“This is the first time we’ve seen a therapy meaningfully alter the course of MacTel,” senior researcher Dr. Martin Friedlander, a professor of molecular and cellular biology at the Scripps Research Institute in La Jolla, Calif., said in a news release.

Based on clinical trial results, the U.S. Food and Drug Administration (FDA) in March approved ENCELTO as the first authorized treatment for MacTel, researchers said.

“This is a step toward redefining how we think about vision loss,” Friedlander said. “Instead of waiting for cells to die, we’re learning how to protect and preserve them.”

MacTel occurs due to problems in the tiny blood vessels under and around the retina, the layer of nerve cells at the back of the eye that detect light and convert it into electrical signals that are sent to the brain, according to the American Academy of Ophthalmology.

The blood vessels leak fluid, causing the nerve cells of the retina to begin to die off. As the cells die, a person gradually loses their central vision, although MacTel usually does not cause total blindness, the AAO says.

MacTel affects about 0.1% of the world’s population, researchers said in background notes.

Implanted in the back of the eye, the ENCELTO device releases ciliary neurotrophic factor (CNTF), a naturally occurring protein known to protect neurons in the retina. 

For the two trials, researchers randomly selected half of a group of 228 MacTel patients to receive ENCELTO. All of the participants were followed for two years.

The device caused a 55% reduction in the rate of retinal cell degeneration in one trial and a nearly 31% reduction in the other, when compared to MacTel patients not provided the treatment.

Other tests also showed a significant slowing in loss of visual function, researchers said.

However, results regarding reading speed were mixed – one trial showed improvement and the other didn’t.

“These differences highlight just how complex it is to measure functional vision loss in a slow-progressing disease like MacTel,” Friedlander said. “If you look at certain functional outcomes from just one of the trials, they're not statistically significant. But when you pool data from both trials — which were conducted the same way — then you see statistically significant results, so we’ll continue to investigate what’s driving that.”

The implant proved effective regardless of how far MacTel had progressed in a patient, suggesting that earlier treatment might be able to prevent more functional vision loss, researchers said.

ENCELTO also caused minimal side effects in patients, researchers said. The most common ones were pinpoint pupils and delayed adaptation to dark surroundings, which occurred in about 17% of trial participants. 

The research team next plans to see whether ENCELTO can protect vision beyond the two years of the clinical trials, and explore why some patients experienced greater benefits from the treatment than others.

“The consistency in preserving retinal cells across both trials gives us confidence in the mechanism,” Friedlander said. “As we refine how and when to treat MacTel, we expect even greater improvements in vision over time.”

Researchers also noted that the ENCELTO capsule could be adapted to release other types of medicines for other degenerative vision diseases.

The clinical trial was funded by Neurotech Pharmaceuticals, the maker of ENCELTO.

More information

The American Academy of Ophthalmology has more on MacTel.

SOURCE: Scripps Research Institute, news release, Aug. 7, 2025