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3.7.2 Torsion calibration
Tests that include torsional tracking (e.g. Advanced Dix Hallpike, Ocular Counter Roll, and Lateral Head Roll)
will need to perform a torsion calibration before use. For these tests, a Torsion calibration button will be
present in the calibration screen (
). Clicking this will open the Torsion Calibration screen.
Figure 3.7-4
Figure 3.7-4: Torsion calibration button
Have the patient look straight ahead, then click on the Auto Detect button. The software will select an iral
segment with good contrast to track rotation. The tracking area can be adjusted using the sliders below the
eyes.
If the torsion tracker is to be utilized in the dark with dilated pupils, it is very important to perform the torsion
calibration in the dark with dilated pupils. If possible, ask the patient to look slightly up – this will make the iris
more visible.
The white circle (tracking area) must never be filled out by the pupil. This will lead to unstable torsional
tracking (
).
Figure 3.7-5
Figure 3.7-5: Adjusting the tracking area in the Torsion Calibration screen
Once the adjustments have been made, click on the Set Reference button. The crosshair will now show a
circle with a crosshair. Confirm that the torsion angle is responding to the patient's eye movements. If not,
adjust the tracking area and click on Set Reference to update. To return to the calibration settings, click on
the Close button (
).
Figure 3.7-6
Figure 3.7-6: Torsion crosshairs with reference area selected in the Torsion Calibration screen
D-0134090-A – 2022/11
VisualEyes™ - Instructions for Use - EN
Page 75
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