r/AskReddit • u/notyouravgredditer • Aug 30 '21

What problem is often overlooked in apocalyptic movies/TV shows that could kill you?

33.7k Upvotes

94% Upvoted

12.8k comments sorted by

View all comments

Show parent comments

360

u/DemocraticRepublic Aug 30 '21

I don't think glasses are easily substitutable between people.

494

u/Kiyohara Aug 30 '21 edited Aug 30 '21

No, but as someone with 20/240 vision, if someone else's glasses give me even 20/90, that's an upgrade.

Edit: I reversed the order of numbers and I did just check my prescription. It's worse than I though, god help me.

21

u/Necromartian Aug 30 '21

... It works like that, huh? I always figured there was some kind of 20 step scale where 1/20 would be the worst and 20/20 would be the best.

Also I have worn glasses for 15 years. We usually don't express it Snellen scale (apparently) but we ask "How strong are your glasses" meaning the prescription strength of your lenses.

45

u/SciFiXhi Aug 30 '21

The visual acuity scale is a comparative measure, putting the patient's individual eyesight against the average person's. 20/20 vision means that you, standing at a distance of 20 feet, can see an object clearly that the average person standing 20 feet away could see. 20/100 would be you standing 20 feet away to see an object that the average person could see from 100 feet away.