A new treatment for patients with a form of congenital retinal blindness has shown success in improving vision, according to results published today in Nature Medicine led by researchers at the Scheie Eye Institute in the Perelman School of Medicine.

A short stretch of RNA delivered in the eye, QR-110, effectively blocked the production of a mutant version of the CEP290 protein in patients with Leber congenital amaurosis, restoring retinal function.

The treatment was designed for patients with CEP290 mutations and a diagnosis of Leber congenital amaurosis (LCA). CEP290 acts as a gate between two compartments of photoreceptor cells—a type of sensory neuron in the retina that converts light into signals that provide vision. Primary photoreceptor blindnesses—such as those caused by CEP290 mutations—are the most common form of LCA and they are currently not treatable.

In this clinical study at sites in the US and Europe, participants received an intraocular injection of an oligonucleotide—a short RNA molecule—created to reduce the mutant CEP290 protein levels in the photoreceptors and restore retinal function.

“It was very dramatic to see one of the patients improve from only being able to differentiate light or dark to reading many letters on an eye chart at two months following the first injection,” says lead author Artur V. Cideciyan, a research professor of ophthalmology. “So, we performed a thorough interim analysis of all results from all patients.”

Ten patients received at least one injection into their worst-seeing eye. At three months after the first injection, half of the patients showed improvements in visual acuity, measured by the ability to either read letters, or distinguish direction of black and white bars.

“This therapy to repair the genetic defect in LCA10 is a breakthrough in treatment strategy, and will open the door for clinical trials in other patients with this condition and other similar conditions that are currently untreatable,” says Samuel G. Jacobson, a professor of ophthalmology and co-lead author of the study.