D-0126440-A – 2020/08
VisualEyes™ 515/525 Instructions for Use - US Page 29
A spontaneous nystagmus test can also be performed as a caloric subtest, which is recommended when
spontaneous nystagmus is present in the caloric position. When spontaneous nystagmus is detected, the
average SPV value can be used to correct the caloric summary by toggling the Spontaneous Correction
option in the left menu panel.
If the wrong ear or wrong temperature was tested by mistake, a message will appear at the end of the subtest
asking if the wrong test was performed. Options for switching to the appropriate ear or temperature will be
available when this message appears. This change is only available upon completing the test and cannot be
changed thereafter.
Caloric tests can display the eye position tracings, pods diagram and optional bar graph or Freyss diagram or
Claussen graph or Haid stoll graph or total amplitude or result table. Unilateral weakness, directional
preponderance and cumulative slow phase velocity information will be present in the upper right corner of the
summary screen.
4.7.12 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 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.
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 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 in order to suppress the
response. Goggle cover is on all reclining chairs and goggle cover is always left off when the test is
performed inside the light tight booth of Orion/System 2000 AT/C Chair. Visual VOR is also like SHA but is
performed with the goggle cover removed even for reclining chair. The patient is instructed to focus on a
target on the TV for reclining chair, a projector screen or stationary OKN drum stripes (laser) on the booth
wall for Orion/System 2000 AT/C chair. 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 to the left 4 cm, back to center, then to the right 4 cm, 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.
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