Doctors use in vivo CRISPR gene editing in the eye, to treat a form of blindness

A patient at the Casey Eye Institute of Oregon Health and Science University in Portland, Ore., was the first to undergo gene therapy inside the human body for a form of blindness.

"Previous gene-editing methods have involved editing genetic material after it was removed from the body," according to a March 4 news release. Doctors call gene therapy inside the body in vivo gene editing

The achievement marks a “significant moment in medicine” said Francis Collins, director of the National Institutes of Health, in an interview  with NPR. “All of us dream that a time might be coming where we could apply this approach for thousands of diseases," said Collins. "This is the first  time that’s being tried in a human being. And it gives us hope that we could extend that to lots of other diseases—if it works and if it’s safe.” 

The patient has a form of inherited blindness called Leber congenital amaurosis. It will take a few weeks for researchers to know whether the CRISPR gene editing worked. If it did, doctors plan to test the treatment on more patients. 

Researchers at Editas Medicine in Cambridge, Mass. and Dublin-based Allergan plan to recruit more than a dozen patients from ages three to 17 years to receive the CRISPR-based therapy in one of three different doses.

Traditional gene therapy is not something that doctors can do to treat this form of blindness, because the defective gene is too large.  

Individuals who have Leber congenital amaurosis have a mutation that does not allow a gene critical for sight to be expressed. That gene is CEP290, and those who are affected often have poor vision at birth, which can deteriorate over time.

CRISPR-based therapy involves using a hair-sized tube to deliver three drops of fluid reagents behind the retina. The patient is under general anesthesia through the procedure, which takes about an hour.