Glaucoma has no warning signs so many people do not realize they have it, increasing the need for early detection, a U.S. ophthalmologist said. Dr. Jess Whitson of the University of Southwestern Medical Center in Dallas recommended people at risk -- those 40 and older, with a family history of glaucoma, or of African-American or Hispanic heritage -- be tested. Using drops in the eyes that dilate a patient\'s pupils, eye care professionals can check for signs of glaucoma, Whitson said. \"With early detection and treatment, vision loss can often be prevented,\" Whitson said in a statement. He recommended having a dilated eye exam every one to two years. Glaucoma -- a cause of blindness -- is a group of diseases that can damage the optic nerve in the eye. In its most common form, fluid builds up in the front chamber of the eye and resulting eye pressure damages the optic nerve. As the disease progresses, people with glaucoma may notice their side vision gradually failing. If left untreated, glaucoma can lead to serious vision loss or blindness as the field of vision narrows, Whitson said.