Each of the patients inherited a condition called Lebers congenital amaurosis, which affects one in 80,000 people in Britain. The condition is caused by a faulty gene which gradually destroys the retina, leaving most patients completely blind by their late 20s.
An 18-year-old man with a rare form of blindness has amazed doctors by navigating a maze after receiving gene therapy to improve his eyesight. Steven Howarth, from Bolton, was among three volunteers with childhood blindness to take part in the world’s first clinical trial of the treatment, led by doctors in London.
Each of the patients inherited a condition called Leber’s congenital amaurosis, which affects one in 80,000 people in Britain. The condition is caused by a faulty gene which gradually destroys the retina, leaving most patients completely blind by their late 20s.
Doctors said the technique represented a “huge advance” and gave hope to thousands of people with so far incurable forms of blindness. If the therapy is effective in other patients, it could revolutionise treatment for more than 100 inherited forms of blindness, affecting 30,000 people in Britain alone.
During a two-hour operation, surgeons from University College London and Moorfields eye hospital injected a harmless virus containing a healthy copy of the RPE65 gene under each patient’s retina. The virus ferries the healthy gene into nearby cells, which then begin working normally. While Howarth’s vision got better after the operation, the other two patients, whose disease was more advanced, have yet to show any significant improvement.
The results of the study, published in the New England Journal of Medicine, coincide with a similar trial led by Jean Bennett at the University of Pennsylvania. All three patients in her trial showed modest improvements in eyesight after receiving the gene injections.
“This really paves the way for developing a treatment for people who have so far had no prospect of a cure,” said Robin Ali, an ophthalmologist at UCL. “If everything goes well, it’s possible that within two to three years it might be approved for use in the clinic.”
The patients’ condition particularly affects their peripheral and night-time vision. In a test before and after treatment, Howarth was asked to walk through a “maze” which recreated a dimly lit street.
“The first time he tried, he was constantly bumping into things and was disoriented but eventually managed to go through the maze. But six months after treatment, he walked straight through as fast as a normal person,” said Ali.
Tests showed Howarth was now able to see in lighting conditions 100 times dimmer than before.
