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10.3 Astigmatism on the posterior cornea
This 4 Maps Selectable display
(Figure 61)
shows only a small amount of anterior (astig. 1.1 D) but a
larger amount of posterior astigmatism (a more defined astigmatic pattern). However, because the
posterior cornea contributes a much smaller amount to the overall refractive state of the eye, the
posterior astigmatism reads only 0.4 D, in spite of a fairly well defined astigmatic pattern.
DIAGNOSIS - normal cornea with posterior astigmatism
Figure 61: 4 Maps Selectable showing posterior astigmatism
10 Screening for refractive surgery
