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Instruction Manual Easygraph
Applications of the height display method
The conventional method of imaging keratoconi by
means of sagittal or tangential radii is prone to
artificial distortion. For example, it not infrequently
leads to an inaccurate location of the apex position.
Clinical findings in conjunction with
fluo images show that images based on height data
yield more accurate results. The conus apex is
always located at the end of the loop-like bulge of
the contour lines. In the fluo image the apex is
located somewhat closer to the loop due to the tilt of
the lens on the eye.
Right eye
Left eye
Representation based on
sagittal radii
The hour-glass shape in the center
is an artifact inherent to the display
method. In the right eye the apex
appears to be located inferior and
nasal, while in the left eye it
appears to be located inferior.
Representation based on
height data
In both eyes the apex position
appears to be located temporal
towards the lower pupillary margin.
This is in agreement with clinical
findings (ophthalmoscopy in
regressive light) and the fluo
image.
Representation based on
tangential radii
Same problem as with sagittal
radii; nevertheless, often yields
more intuitive results.
Simulated
fluo image
Right eye: lens contact in the
apical area temporal and inferior to
the pupillary margin as well as
nasal and superior. Left eye: lens
contact around the temporal/
inferior temporal pupillary margin
as well as nasal between 9 and 10
o´clock.