Patients with Vision Loss See Color Again After Landmark CRISPR Experiment

But not all of the patients.
Derya Ozdemir

Not a week goes by without a breakthrough involving CRISPR. From treating blood disorders to genetically editing mutated cancer cells, CRISPR research has yielded encouraging results in recent years. Scientists have now managed to give some of their vision back to patients suffering from a rare genetic disease called Leber congenital amaurosis, or LCA, which starts to impair one’s sight at birth, and progressively gets worse, eventually making them legally blind.

The trial was done in collaboration with the Casey Eye Institute at the Oregon Health & Science University and the gene-editing biotech startup Editas Medicine. After it was seen that preliminary trials on mice and non-human primates were both safe and encouraging, a clinical trial on humans was organized. 

The preliminary data, released on Wednesday, report on the outcomes of five people. Two were given low doses of the new medication, while the other three received mid-range amounts. And, while more research is needed, the findings could have far-reaching ramifications for anyone suffering from the illness.

How CRISPR was used to give the patients some of their vision back

In previous trials about disorders such as the sickle cell disease, editing of the genes was done in the lab: The scientists had collected blood from the patients, modified the genes in the lab, and injected the “fixed” blood cells back into the bloodstream. But that wasn't possible for the treatment of the eye. So, the researchers had to devise another method of editing the genes. Using CRISPR, a harmless virus that inserts its own genome where the source of LCA disease should reside was stripped of its genetic material and substituted with the altered sequence the patients need.

But that didn’t solve all the problems. The researchers still had to deliver the virus to where it was needed, the retina. That couldn’t be done through the bloodstream, but the cornea is one resilient piece of evolutionary craftsmanship, so the solution could be directly injected into one’s cornea.

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It's the first time scientists used CRISPR like this

Researchers were able to inject a small amount of the solution containing the virus between the cornea and the iris. The solution was applied to only one eye of the volunteers, lest something goes wrong. Of the patients, some didn’t see any change, while for some, it’s too early to say anything. Currently, the team doesn’t have a clear explanation for why not everyone had improved vision and thinks it could be due to the amount of dose or factors specific to each person's biology. It could also be that the other patients need more time before the treatment takes effect. But the results for two of the patients are incredibly promising. 

Carlene Knight (55), from Portland, is happy about the improvements. Her vision has become clearer and brighter, and she can now look for objects instead of aimlessly reaching around. In an interview with NPR, Knight said, "I've always loved colors. Since I was a kid, it's one of those things I could enjoy with just a small amount of vision. But now I realize how much brighter they were as a kid because I can see them a lot more brilliantly now. It's just amazing."

The other participant, Michael Kalberer (43), is starting to have his color vision back after years. "I could see the DJ's strobe lights change color and identify them to my cousins who were dancing with me. That was a very, very fun joyous moment," he said, in an interview with NPR.

While the treatment is far from curing the patients in the trial, some of the changes experienced by the patients are incredibly promising since they are profound enough to have an impact on their daily lives. More patients must be treated and observed for a longer period of time to confirm the treatment's safety, and the researchers have been given permission to proceed to the next group of patients.

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