A Groundbreaking Gene-Therapy to Cure Blindness Passes Trial

A single injection that restores the sight of people with a genetic form of blindness has completed a first gene therapy trial at Oxford University in the UK. The results have been hailed as impressive after 12 patients.

The trial involved 14 patients suffering from Choroideremia, a rare inherited form of blindness, who received an injection of healthy genes into the back of the eye. 12 of the 14 patients either experienced significant gains of more than one line in the eye chart or had no further deterioration of their vision during the five years of the trial.

In the control group that did not receive the gene therapy, only 25 percent of participants maintained their levels of vision over the course of the trial.

Choroideremia affects around 1,200 people in the UK alone and is one form of a group of inherited eye diseases known as retinitis pigmentosa. The disease primarily affects males and is caused by a gene mutation found on the X chromosome. Choroideremia first appears in early childhood as an impairment of night vision and progresses to a complete loss of vision. Until now, Choroideremia was considered untreatable.

Professor Robert Maclaren, an ophthalmologist who led the trial, was very optimistic about the potential of the treatment. “The early results of vision improvement we saw have been sustained for as long as we have been following up these patients. The trial has made a big difference to their lives,” he said.

The success of this first study has led to a larger international gene therapy trial involving over 100 patients in nine European countries and North America. This larger trial is being conducted by Nightstar Therapeutics. “The eye,” according to Nightstar; “is an excellent organ for gene therapy due to its accessibility, small size, compartmentalization and relative immune privileged status (the blood ocular barrier prevents the widespread dissemination of locally administered substances).”

In September 2018, another gene therapy treatment trial for a different eye disease was also started. If these trials are also successful, it could pave the way for gene therapy treatment for other diseases that there are no current treatments for and possibly help hundreds of thousands of people around the world regain eye-sight.