A bioengineered cornea can restore sight to blind people

A bioengineered cornea has restored vision to people with impaired eyesight, including those who were blind before they received the implant.

These corneas, described in Nature Biotechnology today, could help restore sight to people in countries where human cornea transplants are in short supply, and for a lower price. Unlike human corneas, which must be transplanted within two weeks, the bioengineered implants can be stored for up to two years, which could help with shipping them to those who need them the most.

The cornea implant is made from collagen protein extracted from pig skin, which has a similar structure to human skin. Purified collagen molecules were processed to ensure that no animal tissues or biological components remained. The team, from Linkoping University in Sweden, then stabilized the loose molecules into a hydrogel scaffold designed to mimic the human cornea, which was robust enough to be implanted into an eye.

Surgeons in Iran and India conducted a pilot trial of 20 people who were either blind or close to losing their sight from advanced keratoconus. This disease thins the cornea, the outermost transparent layer of the eye, and prevents the eye from focusing properly. The implant restored the cornea's thickness and curvature. All 14 of the participants who had been blind before the operation had their vision restored, with three of them achieving perfect 20/20 vision.

While human cornea transplants in patients with keratoconus are traditionally sewn in using sutures, the team experimented with a new surgical method that's simpler and potentially safer. They used a laser to make an incision in the middle of the existing cornea before inserting the implant, which helped the wound heal more quickly and created little to no inflammation afterwards. Consequently, the patients only needed to use immunosuppressant eye drops for eight weeks, while recipients of traditional transplants usually need to take immunosuppressants for at least a year.

One unexpected bonus was that the implant changed the shape of the cornea enough for its recipients to wear contact lenses for the best possible vision, even though they had been previously unable to tolerate them.

The cornea helps focus light rays on the retina at the back of the eye and protects the eye from dirt and germs. When damaged by infection or injury, it can prevent light from reaching the retina, making it difficult to see.

Corneal blindness is a big problem: around 12.7 million people are estimated to be affected by the condition, and cases are rising at a rate of around a million each year. Iran, India, China, and various countries in Africa have particularly high levels of corneal blindness, and specifically keratoconus.

Because pig skin is a by-product of the food industry, using this bioengineered implant should cost fraction as much as transplanting a human donor cornea, said Neil Lagali, a professor at the Department of Biomedical and Clinical Sciences at Linkoping University, one of the researchers behind the study.

It will be affordable, even to people in low-income countries," he said. There's a much bigger cost saving compared to the way traditional corneal transplantation is being done today."

The team is hoping to run a larger clinical trial of at least 100 patients in Europe and the US. In the meantime, they plan to kick-start the regulatory process required for the US Food and Drug Administration to eventually approve the device for the market.

While the implant has proved effective at treating keratoconus, the researchers believe it could also treat other eye conditions, including corneal dystrophies and scarring from infections or trauma. Additional research is required to confirm this.

Although the cornea donor shortage is not as severe in Western countries as it is in developing countries, the implant could also help reduce waiting lists in richer nations, said Mehrdad Rafat, a senior lecturer at Linkoping University who designed the implants.

We think it could be sold at a higher price in developed countries to balance out the cost of production so we can continue work on other eye conditions," he said. We are very optimistic about that."