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Is there a ratio for diopters of correction and eye length? (self.Blind)
submitted by GTbuddha
All of the time people ask me what is worth with my eyes. I'm a -30.0 in both eyes. I was explaining to a new friend that I'm very near sighted because of my eyes being so long.
He is a math, numbers, logic kind of guy. So he is curious how diopters of power translates into actual eye length. Can anyone help me out?
For example how long is a normal adult eye? Per 10.0 diopters an eye is 1/4 inch longer or something like that. Or is it a logarithmic scale?
He is a math, numbers, logic kind of guy. So he is curious how diopters of power translates into actual eye length. Can anyone help me out?
For example how long is a normal adult eye? Per 10.0 diopters an eye is 1/4 inch longer or something like that. Or is it a logarithmic scale?
Miscsubs123 2 points 2y ago
Yes, approximately each 1mm extra length beyond 23mm gives -3.00 dioptres. So your -30 roughly means your eyeball is 10mm longer than average.
GTbuddha [OP] 1 points 2y ago
Cool thanks!
DrLuobo 1 points 2y ago
Not an eye doctor but I know a few things about vision and lenses...
Dioptres are just reciprocal length, so 1 is 1 / 1 metre. For vision correction this has to do with the focal point, or where the image from your lens is formed. Since your eyes are too long/myopic the image from your lens is being "focused" somewhere in front of your retina instead of on the retina.
The axial length of an adult eyeball is about 23-25mm. A change of 1mm length corresponds to needing about 3D of correction. If we assume your eye is perfect except for the axial length, that would mean your eye is 10mm (about 0.4") too long.
But, that's a big assumption. Things like the curvature, the lens accommodation, and other factors besides length can impact it too. A change of 1mm in the radius of curvature (eye is "flatter" than it should be) also needs correction of 3D. So without knowing more, I don't think it's possible to say exactly.
Dioptres are just reciprocal length, so 1 is 1 / 1 metre. For vision correction this has to do with the focal point, or where the image from your lens is formed. Since your eyes are too long/myopic the image from your lens is being "focused" somewhere in front of your retina instead of on the retina.
The axial length of an adult eyeball is about 23-25mm. A change of 1mm length corresponds to needing about 3D of correction. If we assume your eye is perfect except for the axial length, that would mean your eye is 10mm (about 0.4") too long.
But, that's a big assumption. Things like the curvature, the lens accommodation, and other factors besides length can impact it too. A change of 1mm in the radius of curvature (eye is "flatter" than it should be) also needs correction of 3D. So without knowing more, I don't think it's possible to say exactly.
GTbuddha [OP] 2 points 2y ago
Thanks for your information. This is very helpful.
DrLuobo 1 points 2y ago
Sure, no problem. Glad I could help.
[deleted] 1 points 2y ago
[deleted]
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