A US military veteran who received the world's first whole-eye transplant has made significant progress a year later and has been able to resume his normal life, researchers say.

Aaron James, 46, also received a rare partial-face transplant. He lost most of his face in an accident in 2021 while working as a high-voltage utility lineman.

His donor eye has so far maintained normal pressure and blood flow and retained its size, unlike donor eyes in animals that often shrink after transplants, researchers at NYU Langone Health said in a new study.

Mr James has not regained sight in that eye, but researchers are hopeful he might eventually be able to see out of it again.

They said they were "truly amazed" by Mr James's recovery.

"The outcomes we’re seeing after this procedure are quite incredible and could pave the way for new clinical protocols and inspire further research into complex transplants involving critical sensory organs," said Dr Vaidehi Dedania, Mr James' ophthalmologist.

The study authors said a test called electroretinography - which measures the retina's electrical response to light - showed that the donor eye's rods and cones, the light-sensitive nerve cells in the eye, survived the transplant.

"This electrical response converts light into signals that ultimately the brain could interpret for vision, giving hope for the future of whole-eye transplants with an aim to restore sight," researchers said.

Mr James did not lose sight in his right eye. Last May, he underwent 21 hours of surgery that involved more than 140 healthcare professionals.

The donated face and eye came from a single male donor in his 30s. During the surgery, doctors injected adult stem cells from the donor's bone marrow into the optic nerve to encourage its repair.

Researchers said Mr James had since passed many major milestones, including eating solid foods and being able to smell again.

“I’m pretty much back to being a normal guy, doing normal things,” Mr James said.

The 46-year-old military veteran is only the 19th person in the US to undergo a face transplant and the first person in the world to receive an entire human eye transplant.

Whole-eye transplant surgeries pose a host of challenges because of the complex structure and functions of the organ.

Researchers are now focused on using Mr James's transplant to understand how to restore sight to the eye, said Dr Eduardo Rodriguez, a senior author of the study and the director of the Face Transplant Program at NYU.

Mr James, meanwhile, is now concentrating on sending his daughter, Alice, off to college.

"This has been the most transformative year of my life," he said. "I’ve been given the gift of a second chance, and I don’t take a single moment for granted.”