Why does Richard Belzer wear those dark glasses all the time? Health issues, looks or what?

He did survive testicular cancer (not related to the shades), but I think the reason he wears them is because it's his trademark.

Maybe someone can find a better reason :)

I can, light sensitivity https://www.juf.org/celebrities/celebrity.aspx?id=25398

Here is an interesting exchange with him and an interviewer from TIME Magazine:

Q: What's with the sunglasses all the time, buddy? The '80s are over.

A: I've been wearing sunglasses since the '50s. I had black diapers. I was the first filthy, foul-mouthed counterculture comedian! I was the first guy to wear shades! I was the first guy!

http://content.time.com/time/magazine/article/0,9171,31861,00.html