Patients with an inherited disease that caused them to lose much of their sight early in childhood experienced a quick return of vision after they received gene therapy.

The new treatment addressed the genetic mutation that caused their vision's deterioration, letting them see 100 times better than before.

Some patients even experienced a 10,000-fold improvement in their vision after receiving the highest dose of the therapy, according to researchers from the University of Pennsylvania's School of Medicine.

"One patient reported for the first time being able to navigate at midnight outdoors only with the light of a bonfire."

A total of 15 people participated in the Phase 1/2 trial, including three pediatric patients. Each patient suffered from Leber congenital amaurosis (LCA1) as a result of mutations in the GUCY2D gene, which is essential to producing proteins critical for vision. The rare condition, which affects 100,000 people worldwide, causes significant amount of vision loss as early as infancy.

All subjects had severe vision loss with their best measure of vision being equal or worse than 20/80—meaning if a typically-sighted person could see an object clearly at 80 feet, these patients would have to move up to at least 20 feet to see it. Glasses provide limited benefit to these patients because they correct abnormalities in the optical focusing ability of the eye, and are unable to address medical causes of vision loss, such as genetic retinal diseases like LCA1.