Eye Tissue Transplant

By Nancy Steinbach

This is Steve Ember with the VOA Special English Science Report.

Doctors in Taiwan and the United States have helped people see clearly by replacing damaged eye tissue with special tissue grown in the laboratory.

The two teams of scientists successfully used bioengineered tissue to treat the eyes of people with damage to the cornea and limbus. The cornea is the clear tissue that covers the colored part of the eye. The limbus is the area surrounding the cornea.

The two groups of researchers worked separately. They removed stem cells from the limbus of a healthy eye. The healthy stem cells came from either the patient's healthy eye or from a family member. The scientists grew the cells in the laboratory on amniotic membrane. This is a kind of tissue that surrounds a developing human fetus. The corneal cells grew for several weeks until they formed a layer of tissue five to ten cells thick.

Then doctors cut this tissue and sewed it onto the patients' eyes to replace the damaged tissue. So far, all six patients in Taiwan have improved vision after the operation. They were treated at Chang Gung Memorial Hospital in Taipei. Doctors there reported the results in the New England Journal of Medicine. The American study involved fourteen patients at the University of California at Davis. Ten of them now have improved vision. Those researchers reported their findings in the publication, Cornea.

The researchers do not know if the improvement is permanent. But they say their patients' improved vision has continued for more than a year. The patients could not have been helped by a normal corneal transplant operation because their corneas were too severely damaged.

The new operation will not help people who have been blind since birth or who have damage to the nerve or retina of the eye. It is only for people who can still see at least light and dark. These include people whose corneas have been damaged by burns, chemicals or disease.

Researchers say this new operation could help hundreds of thousands of people in developing countries who suffer from the disease trachoma. Trachoma is one of the leading causes of blindness in the world. Scientists also say the experiment means that other, similar kinds of tissues might also be transplanted. These include tissue from the mouth, lungs and intestines.

This VOA Special English Science Report was written by Nancy Steinbach. This is Steve Ember.