Hmmm, are you referring to Angular Magnification present in glasses
that are worn, such as in this snippet, comparing glasses to contact
lenses?
~
Image distortion caused by an optical system such as glasses and
contact lenses is due to a concept known as "angular magnification".
Angular magnification is defined as "(the visual angle subtended by
the image produced by the system) divided by (the visual angle
subtended by the object without the system). An eye with refractive
error (nearsighted or farsighted) can be though of as a normal eye
with an "error lens" added at the position of the crystalline lens of
the eye. An additional lens then placed either 5mm anterior to the
crystalline lens on the cornea (a contact lens), or placed about 17mm
anterior to the crystalline lens in a glasses frame will then correct
the refractive error introduced by the "error lens". For example, an
eye with no crystalline lens will require a glasses lens of about
+12.00 diopters to correct the vision. The same eye will require a
contact lens power of +14.00 diopters (being 12mm closer to the eye),
and an intraocular lens power of about +15.00 diopters (if the
intraocular lens is placed 5mm inside the cornea). Thus, the eye is
deficient in power by -15.00 diopters.
~
-AI
[Maybe there is an optician out there that knows this in their head] |
