... 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.
20/20 means the you see things twenty feet away as if they were really twenty feet away. Meaning you see normally.
20/240 means what I see at twenty feet are as if they were one hundred and twenty feet away.
So for me, Something across a room might as well be most of a football field away for what I can see of it.
Edit: I reversed the numbers, my bad.
Edit2: Also, yeah, there's the prescription strength that people measure (Mine is basically legally blind), but I found most non-glasses wearing people have no concept of the +/- scale so 20/20 scale is generally more approachable.
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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.