Loss from the “Sneak Thief of Sight” Can Be Diminished with Early Diagnosis and Treatment Prevent Blindness America and Prairie EyeCare Center, PC Join in National Glaucoma Awareness Month in Effort to Save Sight from Second Leading Cause of Blindness CHICAGO(Dec. 19, 2011) – Today, more than 2.2 million Americans age 40 and older have open angle glaucoma, the most common form of glaucoma. At least half don't even know they have it.