Although the patient has not achieved normal vision, the world's first gene transplant for blindness, carried out by a British team, produced an unprecedented improvement in Steven Howarth's sight.
They injected genes only into Howarth's worst-affected eye and used the lowest dose in what they claim was strictly a safety trial.
"The evidence of his improvement is compelling. It is more than we could have expected at this stage of treatment," said Prof Robin Ali, who led the team at University College of London Institute of Ophthalmology and Moorfields Eye Hospital.
In fact, the student suffered from a genetic mutation, called Leber's congenital amaurosis which begins affecting the sight of sufferers in early childhood and eventually causes total blindness during a patient's twenties or thirties.
Currently, there is no treatment for the condition. Born with no peripheral or night vision, Howarth noticed a marked improvement after the two-hour operation. "Now, my sight when it's getting dark or it's badly lit is definitely better.
It's a small change
