U.S. researchers say a new, natural compound may stop diabetic retinopathy -- a leading cause of blindness.

Project investigator Jay Ma of the Oklahoma University Health Sciences Center and Dean A. McGee Eye Institute said when the researchers delivered the new compound to cells using nanoparticle technology, the treatment stopped leakage, blocked inflammation and kept unwanted blood vessels from growing in research models.

"There is no good treatment for retinopathy, which is why we are so excited about this work," Ma said in a statement. "This opens an entirely new area for pharmaceutical companies to target."

The discovery of the compound's function in inflammation and blood vessel formation related to eye disease means scientists can develop new therapies -- such as eye drops -- to stop diabetic retinopathy, Ma said.

Diabetic retinopathy, a disease that affects as many as 5 million Americans, is caused by changes in blood vessels of the retina, the light-sensitive tissue at the back of the eye. In some people with diabetic retinopathy, blood vessels may swell and leak fluid. In others, abnormal new blood vessels grow on the surface of the retina.