While comparing some amusing then-and-now publicity shots of the rock group U2, talk show host Graham Norton couldn't help but ask Bono the question everyone has wondered about with his trademark sunglasses: "Do you ever take them off?" 

Hesitating slightly, Bono decided to play it straight with Norton, telling the host that he's suffered from glaucoma for the last 20 years. "Seriously Graham, you have no idea how this has messed with my life," he said. The 54-year-old went on to explain how, despite his perfect 20/20 vision, doctors diagnosed him with the eye condition after a series of questions. "'Have you ever had any strange visions, like steam coming into the room or rings around lights?,' they asked, and I was like 'Oh yea...'," he shared. 

Early symptoms of glaucoma include light sensitivity, double vision, poor night vision, and even a change in color of the iris. The Glaucoma Research Foundation recommends sunglasses that block 99 percent to 100 percent of UV rays and that also screen out 75 percent to 90 percent of visible light.

While glaucoma left untreated can lead to blindness, Bono says he's perfectly fine and is receiving excellent treatments.

"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.'"

Check out the interview between Bono and Norton below. 

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Michael d'Estries ( @michaeldestries ) covers science, technology, art, and the beautiful, unusual corners of our incredible world.

Glaucoma: The real reason Bono wears sunglasses
U2 rock star recently admitted he suffers from the condition, which can cause extreme light sensitivity and even blindness.