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3.9.1.7
Ocular counter roll
Side mounted/front mounted/top mounted goggle with camera with cover removed can be used for this test.
If user wants to use VORTEQ™ IMU sensor for the test, they can perform the test using either by side
mounted or top mounted goggles as they are compatible for attaching the sensor. Ensure that the patient is
seated in the upright position. Before starting the test, the clinician will need to enter 'Calibration' and then go
to 'Torsion Calibration' to establish the iris signature. The test will then have the patient hold his/her head in
the center, then roll the head to the left and hold, and then roll to the right and hold. When the test is
performed along with the VORTEQ™ IMU, the user is facilitated with additional 3D head model to track the
head movement. Please refer to additional information document for detailed description.
3.9.1.8
Rotary chair tests
The VisualEyes™ system with the optional rotary chair can perform additional tests, including Sinusoidal
Harmonic Acceleration (SHA), Step Test, VOR Suppression and Visual VOR. Rotary chair testing is
completed with the goggle cover on or in the booth enclosure for vision-denied testing. The rotary chair is set
in the upright position to perform the rotary tests. Ensure that the foot brake is disengaged if using the
System 2000 reclining chair. Alerting tasks should be administered during the SHA and Step tests to prevent
the patient from suppressing the nystagmus.
Sinusoidal Harmonic Acceleration (SHA)
Sinusoidal Harmonic Acceleration is a vision-denied test. In this test, the patient is rotated in a sinusoidal
pattern alternating from left to right at octave frequencies from 0.01 Hz to 0.64 Hz for System 2000 and Orion
chairs and 0.01 Hz to 0.32 Hz for the Nydiag 200 rotary chair. Gain, phase and (a)symmetry graphs are
displayed, along with tracings for eye velocity and eye position.
Velocity Step Test
The Velocity Step Test is vision-denied test. This involves rotating the patient in one direction at a constant
velocity for several seconds, then stopping the chair while recording continues. The same process is
completed in the opposite direction. The four steps are then observed for gain, time constants and
(a)symmetry. Step tests are performed at 50⁰/second and 180⁰/second by default, and 100⁰/second as a
standard option. In addition, there are options to test at velocities between 10 and 200⁰/second. To include
spontaneous nystagmus correction, a spontaneous nystagmus sub test can be added to the step test to
provide a baseline nystagmus value. Eye velocity and eye position tracings are displayed.
VOR Suppression
The VOR Suppression test can be performed in the same manner as SHA except that the fixation light within
the goggles is illuminated so that the patient can fixate on the target during rotation to suppress the
response. The goggle cover must be on with reclining chairs and off when the test is performed inside the
light-tight booth of Orion/System 2000 AT/C. Visual VOR is also like SHA but is not vision-denied. The
patient is instructed to focus on a target on the TV with the reclining chair and a projector screen or stationary
optokinetic drum stripes (laser) on the booth wall with Orion/System 2000 AT/C. Visual VOR is typically
performed only at 0.32 Hz.
The Orion/System 2000 AT/C chairs include the subjective visual vertical test for measuring otolith function.
During the test, the goggles are removed from the chair and the patient's head is strapped to the head
support. In the static SVV test, the patient establishes a static visual vertical value by rotating the laser line to
orient the line with the patient's perceived vertical. In the dynamic SVV test (this can be done only with
Auto-Traverse chair), the chair rotates at 300 dps while the chair is aligned at the center axis. The chair is
then moved 4 cm to the left, back to center, then 4 cm to the right, and then the chair is returned to center
and slowed down to a stop. The patient must adjust the laser line at each chair position using the SVV
remote to perceived vertical.
D-0134090-A – 2022/11
VisualEyes™ - Instructions for Use - EN
Page 84
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