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Monday, 10 July, 2000, 23:46 GMT 00:46 UK
Lab-grown corneas 'restore sight'
Eye surgery
New techniques could help people with corneal damage
Human eye tissue has been grown in a laboratory and then successfully transplanted into patients.

The pioneering series of operations will offer great encouragement to people with severe damage to vital corneal cells.

All the 14 patients in the University of California study had badly affected eyesight, but in 10 cases following treatment, vision was either restored or significantly improved.

The scientists used the latest "bioengineering" techniques to grow corneal cells in the laboratory from a very small number supplied either by the patient, if there was one good eye, or a related donor.

Similar techniques are frequently used to "grow" new skin to lay over severe burns.

Protect from damage

The eye cells, called corneal stem cells, are naturally found just underneath the outside of cornea itself, which protects the delicate eye from damage.

The stem cells mature into adult corneal cells which are needed to replace ageing corneal cells or repair injuries.

Certain corneal injuries, such as burns - from fire, radiation or chemicals - and some rare diseases and tumours can destroy the patient's stem cells.

This means that the eye is no longer able to repair itself, and an accumulation of slight injuries destroys the eyesight.

In these cases, a traditional corneal transplant, in which the outermost layer, taken from an organ donor, is simply not enough, as not enough stem cells are carried to replace those lost.

Sterile membrane

The technique, perfected at the University of California Davis School of Medicine and Medical Center, harvests just a few stem cells under local anaesthetic.

These are converted into films just one cell thick in laboratory dishes, and placed on to a sterile membrane which gives them a framework on which to grow.

A thicker layer is eventually produced, which is tough enough to be transplanted.

The stem cells then mature into adult corneal cells so that sight can be restored.

Of the 14 patients at UC Davis, 10 had improved vision.

Professor Ivan Schwab, who led the research, said: "The criteria we had was improved vision with no recurrence of disease, and we did return some vision."

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