May Griffith displays a biosynthetic cornea that can be implanted into the eye to repair damage and restore sight. (Ottawa Hospital Research Institute)

Corneas made in the lab may help restore human vision to the same degree as scarce donor corneas, Canadian and Swedish researchers have found.

The cornea is a thin, film-like layer that covers the surface of the eye and acts like a window. It needs to be transparent to allow light in and focus images properly on the retina at the back of the eye.

But diseases that cloud the cornea are a common cause of blindness. A severe worldwide shortage of donated corneas results in about 10 million untreated patients globally and 1.5 million new cases of blindness each year, studies suggest.

Now an early-phase clinical trial involving 10 Swedish patients with severely distorted or obstructed corneas showed artificial or "biosynthetic" corneas helped regenerate and repair damaged eye tissue and improve vision, researchers report in Wednesday's online issue of the journal Science Translational Medicine.

The implants provided an environment for the patients' own cells and nerves to grow into, resulting in a cornea that looks and functions like a normal, healthy cornea, said senior author Prof. May Griffith of the Ottawa Hospital Research Institute.

Better vision

"These results are very gratifying to show that we've actually been able to make a prototype and we're possibly on the right path," Griffith said from Linköping, Sweden.

In the study, Griffith, Dr. Per Fagerholm, an eye surgeon at Linköping University in Sweden, and their co-authors removed diseased tissue from the patients' corneas and replaced them with biosynthetic implants made of collagen produced in the lab using yeast to mimic the collagen-filled normal human cornea.

The patients were monitored for two years after surgery to check how the implants were incorporated into the eye.

Eventually, the cells and nerves in nine subjects regrew completely to form a regenerated cornea that resembled healthy eye tissue.

For six out of the 10 patients, they were able to see things four times farther away after surgery than before surgery, Griffith said.

What's more, after the subjects were fitted with contact lenses, all had vision equivalent to conventional cornea transplants.

There were no complaints of pain.

No need for steroids

None experienced any rejection or needed to take immune-suppressive steroids in the long-term — two serious side-effects associated with human cornea transplants.

The steroid drops can lead to glaucoma or cataracts, said Keith Gordon, vice-president of research for CNIB in Toronto.

Since artificial corneas are sterilized, they eliminate the potential to transmit infections like viral or prion diseases such as Creutzfeldt-Jakob disease (CJD), Gordon noted.

"The lack of need for steroids and the ability to overcome the potential for donor-derived infection I think are huge aspects in increasing the potential for improved safety and quality associated with corneal transplantation," Gordon said Wednesday.

In the study, the biosynthetic corneas also became sensitive to touch and started producing normal tears, the researcher found.

Surgery changes

During the surgery, suturing the cornea resulted in roughness that was irritating and was corrected with contact lenses.

Researchers continue to improve the materials to make them more mechanically sound, more transparent and compatible with the human body, said Rejean Munger of the Ottawa Hospital Research Institute.

Next, the researchers plan to modify the surgical technique. They are also seeking approval from the health board in Sweden to expand the trial to more people with a wider range of conditions that threaten sight.

Not all types of cornea degeneration have been treated with the new approach, the researchers caution.

The subjects all suffered from keratoconus or scarring of the cornea membrane.

In Ontario alone, there are 6,500 patients with keratoconus, Gordon said.

The new technique could also ensure a safe and even supply of corneas across the country, he added.

At least five more years of research and clinical trials will be needed before artificial corneas become available to the general public.

Brett Hall, a Grade 7 and 8 teacher in Ajax, Ont., has keratoconus and is on a waiting list for a transplant. Hall said the five-year wait may be too long for him, but he is still optimistic.

"I think it's exciting to think that it might not benefit me necessarily but someone with the same condition," said Hall, who likened the effects of the condition to trying to look out a windshield when driving in heavy rain.

The research was funded by the Canadian Stem Cell Network, the Swedish Research Council and County of Ostergotland, and a European Union Marie Curie International Fellowship.