Instruction Manual Easygraph
Page 39
7.5.2.6.1 Vertical Decentration
The large map at the top left shows vertical
decentration calculated according to a Fourier
analysis of height data. Combining the spherical
component with the vertical decentration component
(both generated from height data) makes it possible
to depict the development and different degrees of
severity of keratokonus.
In normal and astigmatic eyes as well as in near-
central keratoconus this display mode yields
perfectly closed rings. In the transition to
keratoconus the rings gradually open up due to the
concomitant decentration, finally taking on the shape
of an inverted omega in the center.
Example:
Normal eye Astigmatic eye
Possible KK Possible KK Incipient KK Incipient KK
Stage 1 KK Stage 1-2 KK Stage 2 KK
Stage 2-3 KK Stage 3 KK Stage 3-4 KK Stage 4 KK
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