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Definition of legally blind/low vision, and other questions (self.Blind)
submitted by der3009
As I understand it, to be legally blind in the US, a person's best corrected vision in the better eye must be 20/200 or worse **OR** a visual field of 20 degrees in diameter. Low vision in the US seems to be looser at 20/70 or worse **OR** 40 degree field in the better eye.
With these definitions in mind, I have a few questions:
1. Why are they testing use of a single eye at a time and not single eyes AND binocular vision?
2. Why do these definitions not take into account individuals with monocular vision or have only 1 eye? (someone with a 40 degree field only in 1 eye, clearly has worse vision than someone with 35 degree vision in both eyes individually).
3. Why do these definitions not take into account the grey area between these minimums? For example, someone with a 45 degree field of vision and 20/65 visual acuity would not be considered low vision. However, it seems obvious to me that this individual has worse vision than someone else with a 20/20 40 degree VF.
Edit: edited example in question 3 from 20/195 to 20/65 to better fit my question.
With these definitions in mind, I have a few questions:
1. Why are they testing use of a single eye at a time and not single eyes AND binocular vision?
2. Why do these definitions not take into account individuals with monocular vision or have only 1 eye? (someone with a 40 degree field only in 1 eye, clearly has worse vision than someone with 35 degree vision in both eyes individually).
3. Why do these definitions not take into account the grey area between these minimums? For example, someone with a 45 degree field of vision and 20/65 visual acuity would not be considered low vision. However, it seems obvious to me that this individual has worse vision than someone else with a 20/20 40 degree VF.
Edit: edited example in question 3 from 20/195 to 20/65 to better fit my question.
jrs12 3 points 4y ago
There is a lot that goes into these questions. There is certainly gray area when it comes to definitions where people could use help, but get left behind because of how the definition of legal blindness is written.
We typically say 20/200 in the better eye after correction because if one eye was 20/20 and the other eye was 20/1000, your brain learns to use the good eye and your binocular vision is most likely to be 20/20. That doesn't mean you won't have problems with depth perception and visual fields, but it does mean you would be able to do things like read small print.
Both eyes need to be affected for legal blindness because we have found that many people function just fine with one good eye. Again, that doesn't mean you don't experience problems, but many people can get by very well with no vision in one eye and perfect corrected vision in the other.
You can't really get into comparing people regarding whose vision is better and whose is worse. The legal definitions are only there to decide who gets money, who can't drive, and who gets certain services. People with vision better than 20/70 can still get driver's licenses in restricted capacities. They can still read print with some accommodations. They may not need canes to travel. People with vision worse than 20/200 are much more all over the board. They may or may not use a cane, braille, or other unique systems that a person with 'better' vision might not need. It all comes down to what people need to perform their major life functions.
We typically say 20/200 in the better eye after correction because if one eye was 20/20 and the other eye was 20/1000, your brain learns to use the good eye and your binocular vision is most likely to be 20/20. That doesn't mean you won't have problems with depth perception and visual fields, but it does mean you would be able to do things like read small print.
Both eyes need to be affected for legal blindness because we have found that many people function just fine with one good eye. Again, that doesn't mean you don't experience problems, but many people can get by very well with no vision in one eye and perfect corrected vision in the other.
You can't really get into comparing people regarding whose vision is better and whose is worse. The legal definitions are only there to decide who gets money, who can't drive, and who gets certain services. People with vision better than 20/70 can still get driver's licenses in restricted capacities. They can still read print with some accommodations. They may not need canes to travel. People with vision worse than 20/200 are much more all over the board. They may or may not use a cane, braille, or other unique systems that a person with 'better' vision might not need. It all comes down to what people need to perform their major life functions.
der3009 [OP] 0 points 4y ago
I don't understand why you can't compare vision. As you said, there is definitely a grey area where people get left behind. If a person, like someone in example 3, needs services, accommodations, or monetary compensation; they won't be able to get any assistance since they are locked out of the system. It doesn't necessarily come down to what they need, rather if they fit the definition. I feel like there needs to be a way to show that an individual who may not fit the definition exactly, still meets the criteria.
theawesomeaquarist 0 points 4y ago
Basically they are just guidelines and anyways vision loss doesn't effect people in the same way
der3009 [OP] 1 points 4y ago
But that's my point. They aren'tjust guidelines, they are strict, steadfast definitions. And someone with worse vision than someone else who fits the definition, wont get the assistance needed.
theawesomeaquarist 0 points 4y ago
I am confused
Why do you want to know this?
Why do you want to know this?
Duriello 3 points 4y ago
I have no answer to your questions, but I'd like to add that, based on my experience, an acuity like 10% isn't even nearly as disabling as a 50% contrast perception, and yet only visual acuity and vision field are considered almost everywhere.
Here in Portugal we have a disability table which, in most cases, multiplies a person's remaining ability by a disability coefficient and subtracts the result from the remaining ability to get a final disability score, and this table does consider monocular vision to be worse than binocular vision. So according to Portuguese law I have a 99% disability score because I'm totally blind (95% for 5% or less acuity in both eyes and 80% for 10 degrees or less vision field in both eyes).
Here in Portugal we have a disability table which, in most cases, multiplies a person's remaining ability by a disability coefficient and subtracts the result from the remaining ability to get a final disability score, and this table does consider monocular vision to be worse than binocular vision. So according to Portuguese law I have a 99% disability score because I'm totally blind (95% for 5% or less acuity in both eyes and 80% for 10 degrees or less vision field in both eyes).
der3009 [OP] 1 points 4y ago
Could you link this table?
Duriello 2 points 4y ago
Sure, it's $1. Beware, the document is huge and is in Portuguese.
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