A British woman has become the first person in the world to undergo gene therapy for the most common cause of sight loss.

Surgeons at the John Radcliffe Hospital in Oxford inserted a synthetic gene into the left eye of Janet Osborne, 80, who suffers from age-related macular degeneration (AMD).

Around 600,000 people in the UK are affected by AMD, which affects the central part of a patient’s vision with gaps or ‘smudges’, making everyday activities like reading and recognising faces difficult.

Mrs Osborne of Oxford, has AMD in both eyes but it is more advanced in the left, leaving her struggling to prepare food, sew and read.

She says her motivation for taking part in the trial was the possibility of helping others with AMD: “I wasn’t thinking of me. I was thinking of other people.

“For me, I hope my sight doesn’t get any worse. That would be fantastic. It means I wouldn’t be such a nuisance to my family.”

The operation involves detaching the retina and injecting a solution containing a harmless virus underneath.

The virus contains a modified DNA sequence, which infects cells, called the retinal pigment epithelium (RPE), and corrects a genetic defect that causes AMD.