Artificial cornea restores sight

Artificial cornea restores sight

Dr May Griffith of the Ottawa Hospital Research Institute, Canada, displays a biosynthetic cornea that can be implanted into the eye to repair damage and restore sight. AP

It worked in a first-stage study of 10 patients in Sweden, researchers reported on Wednesday. And while larger studies are needed, it’s a step towards developing an alternative to standard cornea transplants that aren’t available in much of the world because of a shortage of donated corneas.

“We’re trying to regenerate the cornea from within,” said Dr May Griffith, senior scientist at the Ottawa Hospital Research Institute in Canada and a professor of regenerative medicine at Linkoping University in Sweden.

Vision depends on a healthy cornea, the film-like covering of the eye’s surface that helps it focus light. Corneas are fragile, easily harmed by injury or infection, and about 42,000 people in the US receive transplanted corneas every year. While that’s considered an adequate supply in this country, donated corneas aren’t available in many countries for the estimated 10 million people worldwide with corneal blindness. Transplants also bring risk of rejection.

In addition, researchers are working to improve plastic-like artificial corneas and to create stem-cell treatments that could spur corneal growth.

The new work, published in the journal Science Translational Medicine, is a bioartificial cornea — an attempt to use the same natural substances that make up a real cornea to induce healing.

Crucial work

“I characterise this work as a major advance in the direction that we need to go,” said Dr Alan Carlson, cornea transplant chief at Duke University’s eye centre, who wasn’t involved in the research. To “make this mimic donor tissue to the extent that your own cells ultimately become incorporated in this tissue, I think that’s the most exciting aspect.”

A cornea’s structure is made up of a tissue called collagen. First, researchers took human collagen grown in yeast, made by San Francisco-based FibroGen Inc, and moulded it into a contact lens-looking shape — the scaffolding, essentially, for a cornea.

Then Griffith studied the bioartificial cornea in 10 patients with severe vision loss from damage to a corneal layer. Soon, cells that line a healthy cornea started growing in the collagen. Tear production normalised, and even corneal nerves regrew. There was no rejection, and patients didn’t need immune-suppressing medication.

Two years later, six of the patients had significantly improved vision with glasses. When implanted with contact lenses that previously they couldn’t tolerate, patients saw as well as a similar group of patients who had received standard corneal transplants.

Duke’s Carlson cautioned that these weren’t full-thickness corneal transplants — the lowest layer of the patients’ original corneas wasn’t replaced. People with these more upper-layer corneal problems make up about 10 per cent of transplant cases, he said, while the bigger hurdle is creating therapy for harder-to-treat full-thickness damage to what’s called endothelial cells.

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