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Eye Care Archive (Expert Forum)
what prescription is legally blind?
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what prescription is legally blind?
by shanw413, Dec 07, 2005 12:00AM
I was wondering if it was possible to see what your vision is by your prescription. My prescription is -7.5, I know I'm not 20/20! Is there any way to say what I am?
Doctor's Answer
by Forum-OD-MP, Dec 07, 2005 12:00AM
"legally blind" in my state (Texas) is defined as having worse than 20/70 vision with the BETTER eye thru the best possible rx. in other words, even with the best glasses or contacts on, your "good" eye is still not 20/70. people tell me all the time that without their glasses on they are "legally blind". thats not possible. the definition of legally blind assumes you are wearing the best possible rx.
of course it is certainly possible to be worse than 20/70 w/o your glasses or contacts on. if you really are -7.50, then you are certainly worse than 20/70 at distance (but i'm sure you read 20/20 if the print is close enough!). so what is your actual acuity... who knows? 20/1000? thats just a guess. here's how we do it in our office:
if you cant read the largest letter on our screen (20/400) at 20 feet, then i walk toward you holding up fingers. as soon as you can tell how many fingers i'm holding up, then i write that distance down in the chart. so if you correctly identified the number of fingers i was holding up at 3 ft, then i write "counting fingers at 3 ft". most rx's over say -4.00 cant read the 20/400 letters w/o squinting.
there are of course more scientific ways, and someone could certainly quantify your uncorrected vision by showing you big enough letters. but what would the point be, really? just the shock factor, i guess. unless you are a "low vision" patient (people with permanent vision loss who ARE legally blind and are worse than 20/70 in both eyes WITH their glasses on), then it doesnt really matter exactly how "bad" your vision is w/o glasses. some professions require that you be a certain acuity w/o glasses...like fire fighters and police officers have to be 20/200 w/o glasses or contacts. you are not 20/200 with -7.50. again you are more like 20/1000.
of course it is certainly possible to be worse than 20/70 w/o your glasses or contacts on. if you really are -7.50, then you are certainly worse than 20/70 at distance (but i'm sure you read 20/20 if the print is close enough!). so what is your actual acuity... who knows? 20/1000? thats just a guess. here's how we do it in our office:
if you cant read the largest letter on our screen (20/400) at 20 feet, then i walk toward you holding up fingers. as soon as you can tell how many fingers i'm holding up, then i write that distance down in the chart. so if you correctly identified the number of fingers i was holding up at 3 ft, then i write "counting fingers at 3 ft". most rx's over say -4.00 cant read the 20/400 letters w/o squinting.
there are of course more scientific ways, and someone could certainly quantify your uncorrected vision by showing you big enough letters. but what would the point be, really? just the shock factor, i guess. unless you are a "low vision" patient (people with permanent vision loss who ARE legally blind and are worse than 20/70 in both eyes WITH their glasses on), then it doesnt really matter exactly how "bad" your vision is w/o glasses. some professions require that you be a certain acuity w/o glasses...like fire fighters and police officers have to be 20/200 w/o glasses or contacts. you are not 20/200 with -7.50. again you are more like 20/1000.
Problem is, is that the eyesight of the witness is assumed and the defence team who is representing the witness wont expect me to ask ... for some reason ...
but i need to know that if the witness is 60 years old and its dark out...what could they have that they wouldnt be able to see a traffic light if they werent wearing glasses or the glasses were broken. a red light.
completly hard to find anything definative..please help..
if its the 14 ...dont reply.