If you thought Bono's dark sunglasses came as a part of his superstardom, you're mistaken. Irish rock band U2's front man Bono revealed he has to don shades because he suffers from glaucoma. The star says he has been suffering from the condition for nearly two decades. At a British talk show the singer explained that he had excellent vision but noticed that objects and lights were accompanied by cloudiness and rings - which are symptoms of glaucoma. "I have good treatments, and I am going to be fine," he said. "You're not going to get this out of your head now, and you will be saying, 'Ah, poor old blind Bono,'" he said on the talk show.Glaucoma is caused by a build-up of pressure in the eyeball when the fluid in the eye cannot drain properly, which can damage the optic nerve. If left untreated, it can lead to loss of peripheral vision and ultimately complete loss of sight.