I have supermarket ones – get the weakest that work for you.
Dont do this
the chances of then being correct for you are very slim,and they only do + prescriptions this may not be what you need, als the PD’s of these can be all over the place so can actually cause eye strain, if you dont want to believe someone who works in the industry google which magazines test on them, the outcome was not good…….
Do if you want to get you prescription and shop around, but get proper glasses as prescribed, the above attitude still amazes me as you only have 1 set of eyes and they really are kinda important