The human eye is a particularly promising area for gene therapy because it’s easy to see and gain access to, and it has immune privilege, meaning the body is less likely to reject the new cells introduced during gene therapy treatment.
According to the American Academy of Ophthalmology, the U.S. FDA has approved a gene therapy treatment for an inherited condition that can cause blindness. Luxturna, from Spark Therapeutics, is the first gene therapy treatment approved in the United States for an inherited eye disease called Leber congenital amaurosis. The disease begins in infancy and progresses slowly, eventually causing complete blindness as the retinal cells die.
Treatment does not restore normal vision but allows patients to see shapes and light so they can move around without canes or guide dogs. While it is still unclear how long this treatment will last, most patients studied have maintained their vision for two years. The treatment is designed to help people with a type of retinal dystrophy. This new treatment works only for those patients whose disease is caused by the specific RPE65 gene. Only a genetic test can confirm if this treatment is appropriate. Spark Therapeutics is offering access to genetic testing for select patients. Genetic testing may also be available through a patient’s insurance or through non-profit organizations.
Treatment involves injecting a healthy version of the RPE65 gene into the retina, where it replaces a damaged gene with a healthy version. These retinal cells can then detect light and convert it into signals your brain can understand. As many as 2000 people in the United States may have the kinds of retinal problems that this treatment could help. No other treatment is available for this blinding disease.
Though this specific treatment won’t help many people, its development could make it easier to create similar gene therapies for more common eye conditions in the future. One example is retinitis pigmentosa, which is another inherited retinal disease caused by a defective gene. Researchers hope that one day gene therapy could help restore vision lost by more common diseases such as age-related macular degeneration.