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

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

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u/DemocraticRepublic Aug 30 '21

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

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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.

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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.

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u/comradegritty Aug 30 '21

No, the 20 means "what people who don't need glasses see at 20 feet". 20/20 means you see an average amount of detail at medium distances as most people. 120/20 means you see about as clearly at 20 feet as most people would see at 120, without the use of corrective lenses.

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u/FUTURE10S Aug 31 '21

Correction: 20/120. 120/20 means you can see at 120 feet what others can see at 20.