“We have, for the first time, an effective treatment for the most severe form of childhood blindness, and a potential paradigm shift to treatment at the earliest stages of the disease,” said Professor Michel Michaelides, lead author of the new study describing the use of the therapy, in a statement.

The children involved in the trial were all born with a severe form of retinal dystrophy. Associated with a deficiency of a gene called AIPL1, it causes the rapid and progressive deterioration and death of cells in the retina, the light-sensitive layer at the back of the eye that sends signals via the optic nerve to the brain so we can see. 

As a result, people with this condition are legally certified as blind from birth, with enough sight to detect the difference between light and dark.

“Sight impairment in young children has a devastating effect on their development,” said fellow study author Professor James Bainbridge. “Treatment in infancy with this new genetic medicine can transform the lives of those most severely affected.”

The gene therapy involves injecting healthy copies of AIPL1, contained within a harmless virus, into the retina. It takes advantage of a natural mechanism; the virus infects the retinal cells, whose machinery expresses the protein that the AIPL1 gene encodes. This protein plays a crucial role in the development and function of retinal cells – meaning the therapy allows them to work better and for longer than they otherwise would.

The children, who were all aged between one and three years old when given the treatment, received the therapy in one of their eyes (this was a matter of safety). Over the course of the next three to four years, monitoring revealed that the visual acuity of all four children had “improved substantially”, the researchers wrote.

It’s perhaps best heard from the parents of the children involved, though.

“He started to respond to the TV and phone within a few weeks of surgery and, within six months, could recognize and name his favorite cars from several meters away; it took his brain time, though, to process what he could now see,” said DJ, the mother of Jace, one of the four children treated. “Sleep can be difficult for children with sight loss, but he falls asleep much more easily now, making bedtimes an enjoyable experience.”

Since the treatment was shown to be safe, the team has been administering the therapy to further affected children – and they are hoping it will one day prove feasible to make it more widely available.

“The outcomes for these children are hugely impressive and show the power of gene therapy to change lives,” Michaelides concluded.

The study is published in The Lancet.