Macular telangiectasia (MacTel) type 2 is a disease that damages cells in your eyes that detect light (your retina). When you have MacTel, your central vision slowly gets worse over time because certain cells in your retina break down and blood vessels there change. These changes can make it much harder to see with your central vision, the sight that helps you read and drive.
Diana Do, MD, professor of ophthalmology and vice chair for clinical affairs at Stanford University’s Byers Eye Institute, is a retina surgeon who treats a variety of vision loss conditions including age-related macular degeneration (AMD) and diabetic eye disease. She’s drawn to investigate conditions with unanswered questions that need further scientific study to find effective treatments. She’s spent much of her career on MacTel research.
“Early in my career at the Wilmer Eye Institute at Johns Hopkins University School of Medicine, I spent significant time investigating MacTel,” she says. “With the collaboration of many colleagues, we looked at the natural history of the condition, and in addition, we conducted a clinical trial to evaluate the efficacy and safety of intravitreal injections of anti-vascular endothelial growth factor, also known as VEGF, for MacTel.”
Anti-VEGF injections help stabilize or improve vision in conditions like wet age-related macular degeneration (AMD), diabetic retinopathy (DR), and diabetic macular edema (DME), but the study ultimately showed they weren’t beneficial to improve vision outcomes in MacTel. But, Do says, the work they did during this study vastly increased overall understanding of the condition.
With this deepened knowledge, combined with research done by the MacTel Project, sponsored by the Lowy Medical Research Institute, scientists and doctors around the world have continued to push disease innovation forward.
Advancements in Disease Understanding
Over the past decade, there has been significant progress in research related to MacTel. Through this research, scientists have begun to better understand what’s at the root of the MacTel disease process.
“Over 30 years ago, Mac Tel was considered a retinal vascular disease associated with abnormal, leaky vessels within the retina,” says Do. “However, scientific collaboration through the MacTel Project discovered that MacTel is actually a neurodegenerative condition with Müller cell dysfunction.”
Müller glial cells are supportive cells that are vital to help keep your retina healthy. They help regulate processes like cell death, and they support the structure of the retina. What scientists better understand because of the last decade of research, is that in the MacTel disease process, Müller cells slowly degenerate.
“This leads to disorganization and then atrophy of the outer retina,” says Do. “These degenerative changes lead to vision symptoms and decreased central vision.”
This deeper look into the disease underpinnings has helped lead scientists toward the development of a new treatment aimed at slowing the rate of neurodegeneration.
Encelto: The First FDA-Approved Treatment for MacTel
In March 2025, following two phase III randomized clinical trials with promising results, the FDA approved Encelto as the first treatment for slowing the progression of MacTel.
Encelto is what’s called an encapsulated cell-based gene therapy. A doctor puts it in the gel part of your eye (vitreous cavity) through surgery. The implant is about the size of a grain of rice, and it releases a protein called ciliary neurotrophic factor (CNTF).
Your eye needs CNTF to protect the cells in the retina. By continuously putting out CNTF and nourishing the retina, Encelto preserves photoreceptors and slows the rate of degenerative changes caused by MacTel.
Prior to Encelto, doctors had no proven treatment to slow the progression of MacTel itself. The only tactic to manage the disease was addressing late-stage complications such as new blood vessel growth.
“Encelto has been proven to slow the rate of photoreceptor loss in MacTel,” says Do. “Photoreceptors are important because they are the light-sensitive cells that allow our eyes to see.”
In the clinical trials, Encelto slowed photoreceptor damage by about 55%. The treatment became available to doctors in June 2025.
“This breakthrough is an exciting option because it can help preserve the retinal photoreceptors allowing patients to have a better quality of life,” says Do.
