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8. Measurement procedure
8.4 Using the instrument / taking a measurement
8.4.1 Instructions to the patient
• The patient’s head must be firmly positioned on the chin rest
and the forehead rest. If necessary, a band may be used to
hold the head still.
• Ask the patient to look straight ahead. If necessary, use a
fixation target to keep the eyes still.
• We recommend occasionally reminding the patient during the
examination, to keep his / her eyes wide open. If necessary,
the examiner may use the tips of his fingers to hold the lids
open, taking care not to exert pressure on the eye.
• When elevating the lids, the angle between the microscope
and the lighting unit must be reduced to about 10° so
that the light beam passes through the body of the prism. In
this position it should be possible to obtain an image with no
reflections.
• Immediately before measurement, ask the patient to close
his / her eyes for a few seconds, in order to ensure that the
cornea be sufficiently wetted by the lacrimal fluid containing
the fluorescein solution.
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