Millions of people around the world are blind or have impaired eyesight because of damage to their corneas, the clear outer layer that protects and focuses light into the eyes. And though corneas with mild damage can heal on their own, some people may need a human cornea transplant to regain their vision.
But these procedures, also known as corneal grafts, can be expensive, invasive and time-consuming surgeries that require patients to take medication for more than a year to ensure their bodies don’t reject the tissue. Like other types of donated organs, human corneas must be used quickly—within two weeks of the donor’s death—which can create logistical challenges. In many parts of the world, particularly in poorer areas, there aren’t enough cornea donations to go around.
Now, researchers in Sweden say they’ve developed a novel solution that addresses many of these and other cornea transplant problems: bioengineered cornea implants made from pig skin.
In a small clinical trial, the implants led to eyesight improvements in 20 patients suffering from advanced keratoconus, a condition when the cornea thins and bulges, causing blurry, distorted vision. Fourteen of the 20 participants were blind before the procedure but regained some or all of their sight after receiving the implants; they were also able to wear contact lenses again. Three of the blind patients achieved perfect 20/20 vision after the transplants.
All of the study’s participants continued to tolerate the implants two years after the procedure and did not experience any adverse effects, such as inflammation or scarring.
The researchers shared these and other results in a new paper published last week in the journal Nature Biotechnology.
“It is possible to develop a biomaterial that meets all the criteria for being used as human implants, which can be mass-produced and stored up to two years and thereby reach even more people with vision problems,” says Neil Lagali, an ophthalmologist at Linköping University and one of the study’s authors, in a statement. “This gets us around the problem of shortage of donated corneal tissue and access to other treatments for eye diseases.”
To develop the cornea transplants, the researchers used medical-grade collagen derived from pig skin to create a transparent hydrogel. Surgeons then made a tiny incision in each patient’s cornea and inserted the hydrogel, which helped thicken and reshape the cornea to restore its functionality. This surgical method is also an improvement on traditional transplant procedures, during which surgeons remove the patient’s original cornea and stitch the new one into place. The 30-minute hydrogel procedure was also much faster than a typical cornea transplant, which can take several hours.
Patients in the clinical trial used immunosuppressive eyedrops for just eight weeks after the procedure, compared to the several years of medication that follows traditional transplants. Their bodies did not reject the bioengineered corneas.
"The concept that we could have bioengineered corneas would be revolutionary," says Marian Macsai, an ophthalmologist at the University of Chicago who was not involved in the study, to NBC News’ Aria Bendix. "It would potentially eliminate the risk of rejection and potentially make corneas available to patients worldwide."
Though it’s too soon to tell whether the bioengineered corneas could help patients suffering from other conditions, the technology is showing early signs of promise for those living with keratoconus, which affects one in 2,000 people worldwide, per Johns Hopkins Medicine.
Next, researchers hope to trial the corneas in a study with 100 or more people, then continue toward regulatory approval, NBC News reports. They also hope to experiment with patients who have other eye conditions.
In the long run, their goal is to make bioengineered corneas available in parts of the world with limited resources. Though there is no waiting list for cornea transplants in the United States, per the nonprofit group Eversight, that’s not the case elsewhere. A 2016 study found that some 12.7 million people around the world are in need of cornea transplants—and the researchers want to help reduce that backlog.
“We’ve made significant efforts to ensure that our invention will be widely available and affordable by all and not just by the wealthy,” says Mehrdad Rafat, a biomedical engineer at Linköping University, CEO of LinkoCare Life Sciences AB and one of the study’s authors, in a statement. “That’s why this technology can be used in all parts of the world.”