You definitely don't want to skimp on actual eye care, so definitely call around to different private practices that are well-regarded. You only get one pair of eyes and so many eye diseases can be virtually symptomless and require a caring and expert provider to diagnose and treat them! Oftentimes optometrist offices will have a "private pay" option for an eye exam that's usually around $100 or so. As long as your prescription isn't complicated, as a lot of folks have said, you can use your glasses prescription at whatever optical you so desire.

That being said, a community health center like Blackstone Valley Community Healthcare or Providence would be something to look into if cost is a concern.