Thin sheets of cheek tissue can be used to replace the damaged corneas of people blinded by certain eye diseases, Japanese researchers reported on Wednesday.

Their findings, published in the New England Journal of Medicine, may offer new routes to restoring damaged vision and perhaps also for engineering other types of grow-your-own tissue transplants.

Dr. Kohji Nishida of Osaka University Medical School and colleagues successfully transplanted thin layers of cheek cells onto the eyes of four patients with a rare and painful eye condition that clouded their corneas.

The patients could see afterward, and their new corneas were still clear more than a year later, they reported.

The cornea is the clear layer of cells on the surface of the eye. It can de damaged by trauma or by a range of diseases.

Doctors can take cells from a healthy eye and grow them in a dish to produce a new cornea, or they can transplant corneas from donors. But when both eyes are too badly damaged by accident or disease, those techniques may not work.

Nishida’s team worked with four patients who had Stevens-Johnson syndrome, marked by cloudy corneas, dry eye and pain. Often the eye can regenerate corneal cells but none of the four patients had this ability.

The researchers harvested 3 mm (0.12 inch)-wide squares of mouth tissue from inside the cheeks and grew them into thin layers in the lab.

They used a special low-temperature technique to separate a very thin sheet off each batch and laid it onto the eyes of the patients. The cell layers stuck onto the eye without stitching and developed into tissue that looked and acted like healthy corneas.

“Corneal transparency was restored and postoperative visual acuity improved remarkably in all four eyes,” the researchers wrote. “During a mean follow-up period of 14 months, all corneal surfaces remained transparent. There were no complications.”