EurekAlert! -- WASHINGTON, Mar. 11— A group of scientists in California is trying to develop a cheaper, less invasive way to spot the early stages of retinal damage from diabetic retinopathy, the leading cause of blindness in American adults, before it leads to blindness. As described in the special Interactive Science Publishing (ISP) issue of Optics Express, the Optical Society’s (OSA) open-access journal, the scientists are using beams of light to measure blood flow in the back of the eye.