British doctors have conducted the first clinical trial of a revolutionary gene therapy treatment for blindness.

Researchers at University College London developed the procedure to help adults and children with a condition called Leber's congenital amaurosis (LCA), an inherited retinal degeneration for which there is no effective treatment. 

The team from UCL's Institute of Ophthalmology and Moorfields Eye Hospital was led by Professor Robin Ali and includes leading eye surgeon James Bainbridge and leading retinal specialist Professor Tony Moore.

LCA causes progressive deterioration in vision owing to an abnormality in a particular gene called RPE65.

The technique used in the trial involves inserting healthy copies of the gene into the cells of the retina to help them to function normally. It is hoped that restoring the activity in these cells will restore vision.

"We have been developing gene therapy for eye disease for almost 15 years but until now we have been evaluating the technology only in the laboratory," said Professor Ali.

"Testing it for the first time in patients is very important and exciting, and represents a huge step towards establishing gene therapy for the treatment of many different eye conditions."

Although the initial procedure has been very successful it will be several months until the team can determine the impact of the treatment.

"Some indications of the results of the trial may be available within several months, but the subjects will need to be followed-up to assess the long-term effect of the treatment," said Professor Moore.

"It will be many months before we have the full picture. We anticipate the best outcome in younger patients, as we will be treating the disease in the early stages of development."

Professor Ali added that the results from this first human trial are likely to provide an important basis for many more gene therapy protocols in the future.

However, scientists will still have a lot of work ahead of them as there are many forms of retinal degeneration, meaning that the use of gene therapy must be individually developed and tested in a separate clinical trial specifically for that disease.