Researchers from Northwestern University's Feinberg School of Medicine in Chicago report that one particular type of cell in your retina could cause nearsightedness. The cell is highly sensitive to light and controls how the eye develops. the researchers said If it malfunctions and tells the eye to grow for too long, images don't get focused in the retina as they should. lead investigator Greg Schwartz stated, "The eye needs to stop growing at precisely the right time during childhood.”