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Last Updated: Monday, 8 December, 2003, 02:42 GMT
Artificial corneas moving closer
Corneal damage affects millions worldwide
Artificial corneas have been successfully "grown" in the eyes of partially blind animals.

Scientists from the University of Ottawa are hoping that their findings could lead to an inexhaustible supply of new corneas for human patients.

The cornea is the transparent layer that covers the eye - but it can lose transparency, damaging sight.

Humans are currently the only source of corneas for transplantation, and the supply of donor tissue is limited.

In addition, the artificial corneas may actually work better than human versions - growing their own nerve connections within the eye.

This helps the cornea maintain itself properly, as a loss of sensitivity can lead to ulceration and injury.

The artificial cornea is grown around a "scaffold" of plastic and protein implanted into the eye.

It regenerates the cells necessary to make a fully functioning cornea within a matter of weeks.

Pig success

So far the scaffold has been successfully tested only in pigs with corneal damage.

Pigs given traditional corneal transplants showed no nerve regeneration in the weeks following transplantation.

The Ottawa team suggest that the performance of their artificial cornea may outstrip previous attempts to make one.

They wrote, in the journal Proceedings of the National Academy of Sciences: "Other corneal substitutes have been produced and tested, but we report an implantable matrix that performs as a physiologically functional tissue substitute and not simply as a prosthetic device.

"These replacements should have applicability to many areas of tissue engineering and regenerative medicine, especially where nerve function is required."

Mr Bruce Allan, an consultant ophthalmologist at Moorfields Eye Hospital, told BBC News Online that an artificial cornea needed to have a nerve supply to work properly.

"The holy grail of corneal replacement is to have a normal epithelial skin layer on the surface of the cornea.

"If you can get a cornea with normal surface and normal strength, you've cracked it basically.

"This surface allows minor damage to be repaired. The nerve cells produce factors that help keep this layer of skin healthy."

Corneal diseases affect more than 10 million people worldwide.


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