There are various bands of dental treatment charges, but they are not uncapped so far as I know. Haven't needed that much fun.
Glasses, varies. My last eye test was completely free as I was referred by a doctor. I do pay for classes, but if you want to go economy it's pretty cheap and you can probably have glasses prescribed. I'm pretty much in the budget category even variofocals.
In neither case could I be bankrupted by unlimited uncontrolled charges.