CINCINNATI (WKRC) – A type of eye injury that caused blindness and was previously believed to be irreversible was cured in human trials using stem cells.

The cornea is the the outer layer of the eye, which focuses light and acts as a protective layer. Although the cornea is full of cells that help to repair injuries, if the damage done to it is too severe, it can leave patients with a blindness that was previously believed to be irreversible.

That belief was recently challenged in a clinical trial that was published in Nature Communications. The trial used a new procedure, called cultivated autologous limbal epithelial cells (or CALEC), which involves doctors taking healthy stem cells from the patient’s other eye, growing them in a lab for multiple weeks, and then transplanting them into the damaged cornea.

The researchers behind the trial reported a 92 percent success rate, with 50 percent of the 14 patients reporting fully restored corneas within three months, and 79 percent by 12 months. The cornea restoration returned sight to some of the patients, although not completely, and no patients reported major side effects.

The operation has room to grow, but is an exciting step forward in curing a disorder and injury that was once thought to be a permanent sentence for blindness.