Scientists in China have developed a technique that could revolutionise the treatment of cataracts.
Slit lamp view of cataract in human eye Photo: Rakesh Ahuja, MD (CC BY-SA 3.0)
Experts describe the breakthrough as one of the finest achievements in regenerative medicine.
More than half of all cases of blindness are caused by cataracts - the clouding of the eye's lens. The lens sits just behind the pupil and focuses light on to the retina.
An implanted lens is normally needed to restore sight, but the new operation, described in the scientific journal Nature, activates stem cells in the eye to grow a new one.
The new procedure is less invasive than conventional treatment, which uses ultrasound to soften and break up the lens.
An artificial intraocular lens must then be implanted back into the eye, but this can result in complications, particularly in children.
But the new technique, developed at China's Sun Yat-sen University and the University of California, San Diego, is much more delicate.
It leaves the outer surface of the lens - which is lined with regenerative stem cells - intact.
Researcher Dr Kang Zhang said it was the first time an entire lens had been regenerated.
"The children were operated on in China and they continue to be doing very well with normal vision."
It also showed a dramatically lower complication rate "by almost every measure, supporting the superiority of the treatment".
However, he says larger trials were needed before it should become the standard treatment for all patients.
About 20 million people are blind because of cataracts, which become more common with age, although some children are born with them.
