Twenty people who were legally blind or visually impaired received a transplant of a cornea made from pig collagen. All of them had improved sight, including three who now have 20/20 vision after being legally blind
11 August 2022
Corneas made from pig collagen have restored sight for people who were previously legally blind or visually impaired. Two years after the operations, none of the recipients have reported serious complications or adverse side effects.
More than 12 million people around the world have corneal blindness, which can occur when the eyes’ clear, protective outer layer becomes cloudy or misshapen from damage or disease. Because corneal transplants currently require a human donor, only 1 out of every 70 people in need of care receive one. In many lower-income nations, the cost of the operation further complicates access to treatment.
Mehrdad Rafat at Linköping University in Sweden and his colleagues manufactured a flexible yet resilient dome that resembles a contact lens by extracting and purifying collagen from porcine skin. Following successful trials, the team began testing the artificial corneas in human volunteers.
All 20 people in the trial had corneal blindness due to keratoconus, a condition in which the cornea thins and bulges outward from the centre of the eye. Fourteen were legally blind before the operation and six had severely impaired sight. Afterwards, everyone had improved vision. Three of the formerly blind participants had 20/20 vision following the procedure.
“I remember the first time that the first implant was implanted in one of the patients,” says Rafat. “I couldn’t sleep. I was awake all night, just waiting for the surgeon to let me know, how did the surgery go?” When sight was restored, “it was amazing”, he says. “We got much better results than we expected.”
Because collagen is a structured protein that lacks individual cells, a recipient’s immune system shouldn’t reject the porcine cornea. People with donor corneas usually need to take medication for several years to avoid rejection, while the people in the study used immunosuppressive eye drops for eight weeks.
Esen Akpek at Johns Hopkins University in Maryland says the new cornea may not be as groundbreaking at it first seems. She says that those with keratoconus can often be fitted with custom contact lenses, and that previous alternatives to donor corneas have been engineered but didn’t take off. “It will not cure anyone that cannot be cured with the currently available technology,” says Akpek.
Rafat isn’t sure what the final cost of the procedure will be, but he says it should be more affordable than donor transplants, which can cost tens of thousands of dollars in the US. Further clinical trials will be needed before the porcine cornea could become more widely available.
Journal reference: Nature Biotechnology, DOI: 10.1038/s41587-022-01408-w
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