Can you wear glasses, even bifocals in a sauna?

Question

Because they were fine before I went in, but now they seem like theres a thousand several small cracks in the middle

Answer 1

You should not wear your glasses in the sauna. You probably have the anti-reflection (anti-glare) coating on you glasses. When exposed to very high heat the coating will crack (its called crazing)...this looks like a bunch of crack or scratches in the lens and it cant be fixed. You would need to buy new lenses.

Answer 2

Are they plastic lenses instead of glass?  Plastic frames?  The heat in a sauna is such a dry heat that it sucks the moisture out of plastics, making them brittle.  This may have been the case with your glasses.