For those of you who have misguidedly labored under the impression Bono always wears sunglasses because it’s an asshole rock star thing—well, you’re wrong!

The 54-year-old may well (or may well not) be an asshole rock star, but he wears those sunglasses for a real, valid, medical reason—he has glaucoma.

Bono opened up about his condition—which is caused by a build-up of pressure in the eyeball, and can lead to blindness if not treated—during an interview with Graham Norton, which aired in the U.K. today.

Norton quizzed the U2 frontman, real name, Paul David Hewson, about why he always wears shades, and the singer revealed, "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. You're not going to get this out of your head now and you will be saying 'Ah, poor old blind Bono'."

Poor old blind Bono also addressed the Songs of Innocence iTunes fiasco, which, as Popdust previously reported, he recently explained away as, “a drop of megalomania, touch of generosity, dash of self-promotion and deep fear that these songs that we poured our life into over the last few years mightn't be heard.”

This time round there was no hint of self-deprecation though, as he told Norton, "We wanted to do something fresh but it seems some people don't believe in Father Christmas.

"All those people who were uninterested in U2 are now mad at U2. As far as we are concerned, it's an improvement."

Ah, now, that’s the Bono we love/hate (make your choice) so much!