The largest study of childhood eye diseases undertaken in the U.S. confirms that the incidence of childhood myopia among American children has more than doubled over the last 50 years, USC and the National Institutes of Health announced Wednesday. The findings from the Multi-Ethnic Pediatric Eye Disease Study echo research among adults and children in Asia, where 90 percent or more of the population have been diagnosed with near-sightedness, up from 10 to 20 percent 60 years ago, according to Dr. Rohit Varma, and director of the USC Eye Institute at Keck Medicine at USC.