A new artificial cornea could save the sight of millions of people around the world.
Developed by scientists in Sweden, Canada and California, the new cornea is made from artificial collagen in the lab and, when transplanted into a patient's eye, encourages damaged cells to regenerate and colonize the new tissue. After two years a majority of patients with the artificial corneas had significantly improved vision.
"An artificially fabricated cornea can integrate with the human eye and stimulate regeneration," said May Griffith, a doctor at the Ottawa Hospital Research Institute, the University of Ottawa and Linkping University.
The results were published this week in the journal Science Translational Medicine.
"This approach could help restore sight to millions of people," said Griffith.
The human cornea is a thin, layered and clear tissue that covers parts of the eye such as the colored iris and the pupil. When damaged, the cornea can lead to blurry vision or even complete blindness.
Contact lenses can correct minor problems, but more serious problems can require a full cornea transplant. Clouding of the cornea leads to most cases of blindness worldwide.
The scientists made their artificial cornea from collagen, a common connective tissue found in tendons, ligaments, the cornea itself and other places around the human body. Instead of using natural collagen from humans, however, the scientists created synthetic collagen shaped like a human cornea.
By using synthetic collagen, the researchers eliminated the need for donor corneas, which are often in short supply.
After removing single diseased corneas from 10 patients, the scientists inserted the synthetic corneas in their place. After two years with a biosynthetic cornea the patients' own healthy cells had completely covered the synthetic cornea in nine of the 10 patients.
The new synthetic corneas produced tears and responded to touch. Overall vision improved in six of the 10 patients to a level about the same as a human cornea transplant.
All 10 patients had advanced keratoconus, or central corneal scarring, a disease that thins the cornea while giving the eye a more pointed, conical shape. A person suffering from advanced keratoconus sees multiple images and streaking, and is sensitive to light.
Most of the time a contact lens allows patients with keratoconus to function normally, but severe cases require a full transplant. The exact cause of keratoconus is unknown, but studies have associated the condition with various environmental and genetic factors.
The new results are "very impressive," said Shukti Chakravarti, a professor at Johns Hopkins Medical Institute who was not involved in the study. "There is always a dearth of donor tissue, and this would help bypass that."
Even better, by integrating the cornea recipients' own cells into the synthetic cornea, the patients should fight off infections more easily, and be more comfortable.
"Once those cells grow back they can help contribute to better protection of the cornea," said Chakravarti.
For now the synthetic corneas only work in people with advanced keratoconus, but the doctors and scientists are working to expand the use of synthetic corneas to other eye-related diseases.
"New studies are being planned that will extend the use of the biosynthetic cornea to a wider range of sight-threatening conditions requiring transplantation," said Per Fagerholm, a doctor in Sweden and another co-author of the new study.