Biomedical Engineering Reference
In-Depth Information
62.00 D
58.00 D
4.00 D
B
Position #1
62.25 D
57.75 D
4.50 D
Position #2
61.75 D
58.25 D
3.50 D
C
Position #1
0.50 D
Position #2
0.50 D
Figure 9-14.
A.
Image formation in uncorrected with-the-rule mixed astigmatism.
B.
Image formation when this eye views through a crossed-cylinder lens positioned
so that the vertical meridian is positive (position 1) and negative (position 2).
C.
After
correction of the astigmatism (and any spherical refractive error), the amount of image
blur is the same whether the crossed-cylinder lens is in position 1 or 2. Note that the
sequence of the (line) images reverses when the crossed cylinder is flipped.
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