When most people search for “eye transplants,” they’re picturing a surgeon replacing an entire eye. That procedure doesn’t yet exist in a way that restores vision. What does exist, and has been performed successfully for decades, is corneal transplantation, where the clear front surface of the eye is replaced with donor tissue. It’s the most common type of eye transplant, and it restores sight for thousands of people each year. A landmark 2023 surgery did transplant an entire eye for the first time, but the patient still cannot see out of it. Here’s what’s actually possible today and why full eye transplants remain so difficult.
What Can Actually Be Transplanted
The cornea is the transparent, dome-shaped layer at the front of your eye. It focuses light as it enters, and when it becomes clouded or damaged by disease, injury, or infection, vision deteriorates. Replacing a damaged cornea with a healthy one from a donor is a well-established surgery with strong success rates. At ten years, about 75% of transplanted corneas from middle-aged donors are still functioning. For younger donors (under 34), that figure climbs to 96%.
Beyond the cornea, surgeons can transplant eyelids, tear ducts, and eyelashes, typically as part of facial reconstruction. Researchers are also working on retinal cell transplants using stem cells to replace the light-sensing cells destroyed by conditions like macular degeneration. But the retina, optic nerve, and eye as a whole unit remain outside the reach of routine transplant medicine.
How Corneal Transplant Surgery Works
Corneal transplants come in several forms depending on which layers of the cornea are damaged. The cornea has five distinct layers, and modern techniques let surgeons target only the problem area rather than replacing everything.
Full-thickness transplant (penetrating keratoplasty): The surgeon uses a circular cutting tool called a trephine to remove a button-sized disc through the entire thickness of your damaged cornea. A matching disc from the donor cornea, cut slightly larger (by about a quarter to half millimeter) for a snug fit, is stitched into place using sutures thinner than a human hair. These sutures are placed in a radial pattern at equal tension to minimize uneven curvature in the new cornea, which would blur your vision.
Back-layer transplant (endothelial keratoplasty): If only the innermost cell layer is failing, which happens in conditions like Fuchs’ dystrophy, the surgeon removes just that thin back layer and replaces it with donor tissue. Because the incision is smaller and fewer sutures are needed, recovery is faster and the risk of rejection is lower.
Front-layer transplant (anterior lamellar keratoplasty): When the damage is limited to the front and middle layers of the cornea, the surgeon removes those while leaving the healthy back layer intact. This approach preserves your own inner cells, which reduces the chance your body will reject the graft.
Choosing the right technique matters. Partial-thickness transplants have largely replaced the full-thickness approach for many conditions because they heal faster and carry fewer complications.
Where Donor Tissue Comes From
Donor corneas come from people who have died and whose families consented to organ and tissue donation. Eye banks collect, evaluate, and store these tissues. The FDA allows corneal tissue to be stored under cold conditions for up to 14 days, though most surgeons in the U.S. receive tissue that is three to seven days old because supply generally exceeds demand. Studies have shown that corneas preserved for up to 11 days still have a greater than 90% probability of success at three years. Even tissue stored 12 to 14 days maintains an 89% success rate, though surgeons prefer fresher tissue when available.
Recovery After a Corneal Transplant
Corneal transplant surgery is typically an outpatient procedure, meaning you go home the same day. But recovery is slow compared to other eye surgeries. Full recovery of your eyesight can take up to a year, and vision often shifts unpredictably during that time, requiring frequent check-ups with your eye doctor. You’ll use medicated eye drops for several months to prevent infection and reduce inflammation. Sutures may stay in place for months or even longer, depending on the technique used, and your doctor will adjust or remove them based on how the cornea heals and whether it develops uneven curvature.
You won’t have perfect vision right away. Many people need glasses or contact lenses after the transplant to correct remaining irregularities. Some need additional procedures down the road to fine-tune the result.
Graft Rejection and Long-Term Risks
Your immune system can recognize the donor tissue as foreign and mount an attack against it. This is called graft rejection, and it’s the primary long-term risk of any corneal transplant. Signs include increasing redness, sensitivity to light, worsening vision, and pain. Rejection can happen weeks, months, or even years after surgery. Catching it early is critical because prompt treatment with anti-inflammatory drops can often reverse the process and save the graft.
Partial-thickness transplants carry a lower rejection risk than full-thickness ones because less foreign tissue is introduced. Back-layer transplants in particular have become favored partly for this reason.
Limbal Stem Cell Transplants
Some eye conditions destroy the stem cells that live at the border between the cornea and the white of the eye. These limbal stem cells are responsible for keeping the cornea transparent and healthy by continuously regenerating its outermost layer. When they’re wiped out by chemical burns, autoimmune disease, or other injuries, the cornea becomes cloudy and scarred, and a standard corneal transplant won’t work because the new tissue will fail without functioning stem cells to maintain it.
In a limbal stem cell transplant, healthy stem cells are harvested either from the patient’s other eye (if only one eye is affected) or from a donor. When donor cells are used, the patient needs long-term immune-suppressing medication to prevent rejection, which makes this option more complex and riskier, especially for older patients or those with other health conditions. The goal is to restore the stem cell population first, creating a healthy environment that can then support a corneal transplant if one is still needed.
The First Whole Eye Transplant
In May 2023, surgeons at NYU Langone Health performed the world’s first whole eye and partial face transplant on Aaron James, a military veteran who had lost his left eye and part of his face in a high-voltage electrical accident. The surgery took 21 hours.
One year later, the transplanted eye had maintained normal blood pressure and blood flow. Testing with electroretinography, which measures the retina’s electrical response to light, showed that the light-sensing cells (rods and cones) survived the transplant and were still generating electrical signals. This was a remarkable biological milestone: transplanted retinal cells, alive and responding to light in a new body.
But James cannot see out of the eye. The optic nerve, which carries visual signals from the retina to the brain, did not reconnect. Noticeable damage to the optic nerve during recovery led to some loss of retinal tissue. The eye looks healthy and cosmetically normal, but it does not produce vision.
Why Whole Eye Transplants Can’t Restore Vision Yet
The optic nerve is the bottleneck. It contains over a million nerve fibers that relay precise visual information from the retina to the brain, and once those fibers are cut, they rapidly degenerate. Unlike skin or bone, nerve cells in the central nervous system have extremely limited ability to regrow. Even if scientists could coax the nerve fibers to regenerate, they would need to reconnect in exactly the right pattern. A scrambled reconnection would send garbled signals to the brain, producing no useful vision.
There’s also a neurological dimension beyond the nerve itself. After transplantation, the brain’s visual processing system would need to reorganize and essentially relearn how to interpret signals from the new eye. Differences between the donor eye’s anatomy and the patient’s original neural architecture would require a cognitive adaptation phase that scientists don’t yet know how to facilitate.
Researchers are pursuing several strategies: injecting growth factors to encourage nerve regeneration, using gene therapy to reprogram retinal cells into a growth state, and exploring stem cell approaches to rebuild lost connections. Some teams believe a vision-restoring whole eye transplant could become possible within a decade, but the gap between keeping an eye alive in a new body and actually seeing through it remains enormous.