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8. Problem solving
2. The measurement prism does not touch the cornea or too much force has been applied
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Cause:
If the patient pulls his/her head back even
slightly, the pulses will become irregular and
measuring prism contact with the eye will
become intermittent. If the patient pulls his/
her head even further back, the fluorescein
semi-circles will completely disappear.
Correction:
If possible, use a band to hold the patient’s
head in place.
Cause:
If during measurement the slit lamp is moved
forward toward the patient or the patient moves
toward the slit lamp, the sensor arm will be pushed
into contact with a stop spring. The applanation
surface will be too large. The image will not change
when the measurement drum is rotated.
Correction:
Retract the slit lamp until regular pulses and a
correspondingly smaller applanation surface
are obtained. This is the correct measurement
position, in which variations in pressure
will not cause immediate variations in
the applanation surface.
