Eye vision... 6/9 (20/30) What does it mean??
Question: I understand the eye vision as +3, -5, etc.
Can anyone accurately tell what the following visions are if converted to something like +/-3.5
Distant Vision
6/9 (20/30) Corrected or uncorrected in each eye.
6/6 (20/20) both eyes
Near Vision
N5 at 30 – 50 cm
Thanks a million!
Answers: That looks like the entrance requirement for a career, but note that it *doesn't* care whether you wear glasses or contacts, or how strong they are, as long as your vision is fair to good in each eye, and good with the two eyes together,
I could make that standard, and my Rx hits -14.25 in the worst meridian of the worst eye.
6/9 vision, the ability to see at six metres what a (notionally)normal eye can see at nine metres is still, for example, comfortably within the driving standard minimum.
It depends a lot on pupil size, so there is no direct conversion, but someone not wearing their Rx of -0.50 to -0.75 might have 6/9
With plus lenses it's not so easy because, especially when young, people can compensate to some degree.
A teenager with +3.00 of more might still have 6/9 or better without their glasses, at least until they got tired.
And make it less simple (Sorry!) some people have eyes that can never get to 6/9 *whatever* glasses thay have:
Amblyopia, pseudopapilloedema, congential cataracts...
Less than perfect vision isn't always down to simply needing a spectacle Rx.
If you're young and meet the distance requirement, the near one of N5 won't be a problem.
It sounds like you see at about 2/3 of normal vision at a distance. There is some myopia (nearsightedness) and you might need glasses or contacts.
For example...you can see an object clearly at 3 feet, slightly blurry at 6 feet and really blurry at 9 feet.
EMT
If I'm wrong, let me know...but it seems you are nearsighted (just like millions of others).
us cellular is the worst phone company ever
keep posting over yahoo answers
bad
it means someone with 20/20 vision could see something at 30 feet away, but you would have to be 20 feet away to see it..
Hi...
20/20 is perfect vision so start from there
When a 'normal' person stands at 20 feet and can see a letter that is 5 degrees high, that's called a 20 foot letter. Since he is at 20 feet, the 20/20 letter.
If he moves back to 40 feet, and still sees that same 5 degrees, the letter will have to be twice as high (he's twice as far). When he stands at 20 feet, it's easy to see that twice as big 20/40 letter.
Same for 100 foot letter, it's larger, but still subtends that same 5 degrees. It's just 5 times bigger than the 20 foot letter.
But if a person stands at the 20 foot line, and the best he can see is the 100 foot letter, he sees 20/100.
The diopters of the correction is related to distance as well. The power of the lens system or lens is equal to 1/d where d is in meters.
If a lens focuses light a meter away, that's +1.00
half meter away, +2.00
third of a meter away, +3.00
quarter of a meter away, +4.00.
So someone who is nearsighted, and already too powerful and sees clearly an object about a third of a meter away, this person is +3.00 too powerful, so would need a -3.00 lens to move that focal point out to infinity, and be able to see clearly out there.
A rule of thumb is that each line onthe visual acuity chart corresponds to a .25D. So 20/20 being zero, 20/25 would be -0.25 and 20/30 would be -0.50. So if your vision is 20/20 with both eyes you would not require any type of correction for distance vision.
idk
Can anyone accurately tell what the following visions are if converted to something like +/-3.5
Distant Vision
6/9 (20/30) Corrected or uncorrected in each eye.
6/6 (20/20) both eyes
Near Vision
N5 at 30 – 50 cm
Thanks a million!
Answers: That looks like the entrance requirement for a career, but note that it *doesn't* care whether you wear glasses or contacts, or how strong they are, as long as your vision is fair to good in each eye, and good with the two eyes together,
I could make that standard, and my Rx hits -14.25 in the worst meridian of the worst eye.
6/9 vision, the ability to see at six metres what a (notionally)normal eye can see at nine metres is still, for example, comfortably within the driving standard minimum.
It depends a lot on pupil size, so there is no direct conversion, but someone not wearing their Rx of -0.50 to -0.75 might have 6/9
With plus lenses it's not so easy because, especially when young, people can compensate to some degree.
A teenager with +3.00 of more might still have 6/9 or better without their glasses, at least until they got tired.
And make it less simple (Sorry!) some people have eyes that can never get to 6/9 *whatever* glasses thay have:
Amblyopia, pseudopapilloedema, congential cataracts...
Less than perfect vision isn't always down to simply needing a spectacle Rx.
If you're young and meet the distance requirement, the near one of N5 won't be a problem.
It sounds like you see at about 2/3 of normal vision at a distance. There is some myopia (nearsightedness) and you might need glasses or contacts.
For example...you can see an object clearly at 3 feet, slightly blurry at 6 feet and really blurry at 9 feet.
EMT
If I'm wrong, let me know...but it seems you are nearsighted (just like millions of others).
us cellular is the worst phone company ever
keep posting over yahoo answers
bad
it means someone with 20/20 vision could see something at 30 feet away, but you would have to be 20 feet away to see it..
Hi...
20/20 is perfect vision so start from there
When a 'normal' person stands at 20 feet and can see a letter that is 5 degrees high, that's called a 20 foot letter. Since he is at 20 feet, the 20/20 letter.
If he moves back to 40 feet, and still sees that same 5 degrees, the letter will have to be twice as high (he's twice as far). When he stands at 20 feet, it's easy to see that twice as big 20/40 letter.
Same for 100 foot letter, it's larger, but still subtends that same 5 degrees. It's just 5 times bigger than the 20 foot letter.
But if a person stands at the 20 foot line, and the best he can see is the 100 foot letter, he sees 20/100.
The diopters of the correction is related to distance as well. The power of the lens system or lens is equal to 1/d where d is in meters.
If a lens focuses light a meter away, that's +1.00
half meter away, +2.00
third of a meter away, +3.00
quarter of a meter away, +4.00.
So someone who is nearsighted, and already too powerful and sees clearly an object about a third of a meter away, this person is +3.00 too powerful, so would need a -3.00 lens to move that focal point out to infinity, and be able to see clearly out there.
A rule of thumb is that each line onthe visual acuity chart corresponds to a .25D. So 20/20 being zero, 20/25 would be -0.25 and 20/30 would be -0.50. So if your vision is 20/20 with both eyes you would not require any type of correction for distance vision.
idk
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