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000000Ć1150Ć839 IOLMaster 11.02.2004
How to adjust the measuring marks
Ask the patient to look at the yellow fixation light. If the patient cannot
see the fixation light instruct him or her to look straight ahead into the
instrument.
Note:
The peripheral infrared measuring marks are invisible to the
patient. (However in a darkened room an attentive observer may
perceive the measuring marks as faint red dots when looking into
the projectors of the keratometer.)
When aligning the instrument, take care that
all the six peripheral
measuring marks
are visible and that they are lying as concentric as
possible to the two auxiliary circles on the display. By varying the diĆ
stance between patient and instrument,
optimally focus
the images
of the six peripheral measuring marks on the display. The images of the
measuring marks should be circular or ellipsoid.
To improve the reflectivity of the cornea it is advisable to ask the patient
to close and open the eyes several times. In this way, the tear film is
replenished and imaging of the measuring marks improved.
As a reminder, an appropriate message will appear below the video
image when you activate the keratometer mode.
Fig. 54 Optimally aligned instrument (without crosshairs and auxiliary circles;
the central fixation point is distinctly fainter than the six peripheral
measuring points)
Image of fixation point
(irrelevant for the
measurements)
Explanation:
Depending on the reflectivity of the cornea the display monitor image
of the central fixation point may be barely visible. This is insignificant for
the calculation of the corneal curvature. Most important is sharp focusĆ
sing of the peripheral marks.
Tips for keratometer measurement
