27 October 2011 Last updated at 16:08 GMT
By Pallab Ghosh Science correspondent, BBC News
Researchers in Oxford have treated a man with an advanced gene therapy technique to prevent him from losing his sight.
It is the first time that anyone has tried to correct a genetic defect in the light-sensing cells that line the back of the eye.
The president of the Academy of Medical Sciences said the widespread use of gene therapy of this treatment will be soon be possible.
The operation was carried out on 63-year-old Jonathan Wyatt, an arbitration lawyer based in Bristol.
Mr Wyatt was able to see normally until about the age of 19 when he began having problems seeing in the dark.
He was told by doctors that his vision would get progressively worse and he would eventually go blind.
“The worst occasion was when I was reading out a statement to the court and I made a mistake. The judge turned to me and snapped ‘Can’t you read Mr Wyatt?!’ I then decided it was time to put my wig down and leave advocacy.”