The world's first transplant of this organ was called a giant step for science

However, they have not yet been able to return their vision.

Three years ago, utility foreman Aaron James lost half his face and an arm when a high-voltage electrical cable fell on him. In 2023, a man underwent a first-of-its-kind face and whole eye transplant. The operation took 21 hours and involved 140 medical workers. A year later, scientists shared their successes in eye transplantation.

Aaron James has reportedly made significant progress after receiving an eye and skin transplant. Although he cannot see with the transplanted organ, it maintains normal pressure and blood flow, which is a positive result given previous attempts at eye transplants in animals in which these values ​​were reduced. Doctors noted that the operation created "the basis for further advances and ongoing research."

Although face transplants have been performed before, they have become part of surgical practice relatively recently: the first partial transplant was performed in 2005, and the first full in 2010. As of September 2023, 50 such operations have been performed worldwide. Tens of thousands of cornea transplants, partial eye transplants, are performed every year, but they are a much simpler procedure.

“The optic nerve transmits electrical signals to the visual cortex of the brain. This nerve is part of the central nervous system, so connecting one eye and the associated nerve to the other brain is an extremely difficult task,” scientists explain the complexity of the operations.

In quantitative terms, this is statistically one of the most difficult rewiring operations, since the optic nerve consists of approximately 1.2 million nerve cells. Matching each of these to the corresponding optic nerve and cortex of another person is almost impossible, especially given the possible differences in the number of nerves between people.

“Each nerve is responsible for a specific area of ​​vision and is connected to a specific part of the brain,” the researchers explain.

Retinal cells also present additional complexity. They are very fragile and require a constant blood supply; without oxygen they die in just 12 minutes. To solve this problem, the surgeons who performed James' surgery ensured that the blood supply to the donor eye was preserved.

Previous animal studies suggest that reactivating embryonic signaling pathways can stimulate stem cells in the body, which helps nerve repair. Some vertebrates, such as newts and zebrafish, are able to regenerate their retinas even after significant damage.

Stem cells have shown promising results in treating blindness caused by damage to the outer layer of the eye, especially when a person has one eye damaged. Stem cells from a healthy eye can be extracted, grown in the laboratory and then transferred to the damaged eye to restore functionality.

If both eyes are damaged, donor stem cells from fresh cadaver eyes can be used. However, the recipient must take immunosuppressive medications throughout his life, which can lead to complications such as an increased risk of viral, bacterial, or fungal infections.