Isabella Beukes, of Santa Rosa, Calif., has been legally blind for more than 40 years. An experimental treatment derived from embryonic stem cells seems to have enabled her now to see not just color but also some shapes. Tim Hussin for NPR hide caption

Isabella Beukes, of Santa Rosa, Calif., has been legally blind for more than 40 years. An experimental treatment derived from embryonic stem cells seems to have enabled her now to see not just color but also some shapes.

Scientists are reporting the first strong evidence that human embryonic stem cells may be helping patients.

The cells appear to have improved the vision in more than half of the 18 patients who had become legally blind because of two progressive, currently incurable eye diseases.

The researchers stress that the findings must be considered preliminary because the number of patients treated was relatively small and they have only been followed for an average of less than two years.

But the findings are quite promising. The patients had lost so much vision that there was no expectation that they could benefit, the researchers say.

"I'm astonished that this is working in the way that it is or seems to be working," says Steven Schwartz, a UCLA eye specialist who led the study, which was published Tuesday in the British medical journal The Lancet. "I'm very excited about it."

Other researchers agreed the work is preliminary, but also highly promising.

"It really does show for the very first time that patients can, in fact, benefit from the therapy," says Dr. Anthony Atala, a surgeon and director of the Wake Forest Institute for Regenerative Medicine at Wake Forest University.

What we did is put them into patients who have a disease where those particular cells are dying; and we replaced those dying tissues with new tissue that's derived from these stem cells. In a way it's a retinal transplant.

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Embryonic Stem Cells Restore Vision In Preliminary Human Test