PIONEERING gene therapy by Oxford researchers has restored the vision to patients who would otherwise have gone blind.

New research from Oxford University published today shows the therapy can restore some vision in people suffering choroideremia - a rare form of genetic blindness.

The technique involves injecting a virus into the eye, delivering millions of healthy genes to replace a gene patients with this rare disorder are missing.

Doctors at the university have examined the vision in six patients for four years after they were given the gene therapy at the John Radcliffe Hospital.

The choroideremia patients - who are missing a key gene in their retina - were given a dose of the treatment in their left eye and monitored during the study.

While the initial therapy was designed to slow or stop sight loss, two of the patients experienced significant improvement to their vision which was sustained over the four-year period.

Lead investigator Professor Robert MacLaren said the new results provide "unequivocal proof" the effects of the gene therapy are sustainable.

He added: "There have recently been questions about the long term efficacy of gene therapy, but now we have unequivocal proof that the effects following a single injection of viral vector are sustained.

"Even sharpening up the little bit of central vision that these patients have can give them considerable independence."

Professor MacLaren, consultant ophthalmologist at the Oxford Eye Hospital, hailed gene therapy as having great potential halt diseases before they even start.

He added: "Gene therapy is a new technique in medicine that has great potential.

"As we learn more about genetics we realise that correcting faulty genes even before a disease starts may be the most effective treatment."

Professor MacLaren added: "In brief, this is the breakthrough we have all been waiting for.”

Gene therapy uses the infectious properties of a virus to insert DNA into cells, but the DNA is reprogrammed in the labs to correct faulty genes in patients instead of infect them with a virus.

The researchers believe the technique could provide a single treatment for many types of inherited blindness including retinitis pigmentosa, which affects young people, and age-related macular degeneration, which affects people as they get older.

The project was a collaboration between the university and OUH with funding from the NIHR Oxford Biomedical Research Centre and the Department of Health and Wellcome Trust.