What is my vision when wearing glasses?!
Question: What is my vision when wearing glasses!?
I mean what do they aim for, average vision, 20/20, or better!?
I presume there is some sort of standard!.
I'm in England, if there's a difference!.Www@Answer-Health@Com
I presume there is some sort of standard!.
I'm in England, if there's a difference!.Www@Answer-Health@Com
Answers:
20/20 is obsolete in the UK and anwhere else that uses metric measurments: Europe, Asia!.!.!. though it's still understood!.
The 20 refers to the test distance, 20ft, and the metric equivalent is 6 metres, 20/20 = 6/6, 20/40 = 6/12
The normal aim in refraction is to get each eye to its best focus!. More lens power does not give more vision!.!.!.
It's much more like tuning in a radio station!.
Having found the "best spot", the vision that results is not set by the power of the glasses, but the quality of the lens / eye / retina / nerve / brain system as a whole!.
If there's cataract, amblyopia or macular degeneration, for example, no Rx lens is going to produce 6/6!. The principle acuity limit isn't in the focal length error!.
Most healthy eyes, with appropriate correction if required, can achieve 6/6, many can do somewhat better, 6/5 or even 6/4 occasionally and 6/3 very rarely, but having 6/9 as best is normal for some people (but that would only be concluded when the possibility of problems had been considered, as in most cases 6/9 best acuity would mean something needed looking at!.)
6/6, 20/20 is just a very rough shorthand for "pretty good vision"!. It's not an ideal or a particular objective!. People vary too much!. 6/6 is not a solid safe, good, benchmark!.
Someone capable of 6/3 would not consider 6/6 "clear vision" at all, and they'd be right!.
And someone with 6/6 could have such severe glare difficulties from early cataract that they needed surgery!.
(Not theoretical: I've met both instances)Www@Answer-Health@Com
The 20 refers to the test distance, 20ft, and the metric equivalent is 6 metres, 20/20 = 6/6, 20/40 = 6/12
The normal aim in refraction is to get each eye to its best focus!. More lens power does not give more vision!.!.!.
It's much more like tuning in a radio station!.
Having found the "best spot", the vision that results is not set by the power of the glasses, but the quality of the lens / eye / retina / nerve / brain system as a whole!.
If there's cataract, amblyopia or macular degeneration, for example, no Rx lens is going to produce 6/6!. The principle acuity limit isn't in the focal length error!.
Most healthy eyes, with appropriate correction if required, can achieve 6/6, many can do somewhat better, 6/5 or even 6/4 occasionally and 6/3 very rarely, but having 6/9 as best is normal for some people (but that would only be concluded when the possibility of problems had been considered, as in most cases 6/9 best acuity would mean something needed looking at!.)
6/6, 20/20 is just a very rough shorthand for "pretty good vision"!. It's not an ideal or a particular objective!. People vary too much!. 6/6 is not a solid safe, good, benchmark!.
Someone capable of 6/3 would not consider 6/6 "clear vision" at all, and they'd be right!.
And someone with 6/6 could have such severe glare difficulties from early cataract that they needed surgery!.
(Not theoretical: I've met both instances)Www@Answer-Health@Com
They do aim for 20/20 (or 6/6 in Europe, I think, because of the metric system) because that is assumed to be average vision!.
If your vision is easily correctable to 20/15 and that correction doesn't cause strain, they'll do that!. The amount of correction they can achieve can vary between the two eyes as well; for example, in my right eye I can see 20/15 with glasses, and in my left eye it varies between 20/20 and 20/25--partly due to the degree of astigmatism in my left eye!.Www@Answer-Health@Com
If your vision is easily correctable to 20/15 and that correction doesn't cause strain, they'll do that!. The amount of correction they can achieve can vary between the two eyes as well; for example, in my right eye I can see 20/15 with glasses, and in my left eye it varies between 20/20 and 20/25--partly due to the degree of astigmatism in my left eye!.Www@Answer-Health@Com
They aim for 20/20!. However, some people cannot be corrected to 20/20 for whatever reason and others easily correct to 20/15 or better!.Www@Answer-Health@Com
It depends on the eye and how good the presciption is the goal is always at least 20/20 but it could be better or worse than 20/20!.Www@Answer-Health@Com
They want 20/20, if possible!.
It's universal!.Www@Answer-Health@Com
It's universal!.Www@Answer-Health@Com