Aero helmet : Visor or no visor ?

You actually can remove the visor without damaging it (as long as it hasn't been modified somehow post-factory).

But... I had one of these, and sold it without ever riding in it. The visor never fit right for my face, and the angle of it put it right into my face hard.

But if that's not the case for you, then by all means keep it on. You can fit some close-fitting glasses under it (though the fast that they'd be close-fitting may cause sweat problems). Lots of people use this helmet sans visor. I have a Rudy Project Syton Open now, which fits me like it was custom made for my noggin. No visor on that one.

But I think the helmet and visor makes more of a difference INSIDE your head than outside, which is probably MORE effective.