Turns out Bono hasn't been wearing sunglasses nonstop for two decades just because he's Bono -- he says he's been suffering from glaucoma all this time.

The iconic U2 frontman, 54, revealed the malady during an interview on BBC1's 'The Graham Norton Show,' according to the Guardian. When Norton asked if he ever removes his seemingly omnipresent shades, Bono said, “This is a good place to explain to people that I’ve had glaucoma for the last 20 years. I have good treatments and I am going to be fine.”

Glaucoma is actually no joke. It's caused by a buildup of pressure in the eyeball which can damage the optic nerve and lead to blindness if not treated. But if it's diagnosed early enough, laser treatment or surgery can be used to stop it from worsening -- but the damage to the optic nerve can not be repaired.

U2 appeared on the show in support of their latest full-length, 'Songs of Innocence,' which you might remember from it unexpectedly appearing on your Apple device a few weeks ago. The band also recently unveiled the official video for the lead single, 'The Miracle (of Joey Ramone),' which you might remember from all those Apple commercials.

U2 -- 'The Miracle (of Joey Ramone)' Official Music Video