Fig. 4.

Patient #10 with bilateral VOR loss. The left panels show the eye and head velocity during head impulses to the left (top) and right (bottom) recorded with ICS Impulse goggles. Note how during head impulses towards either side the eyes do not move as quickly as the head. Then, subsequent corrective eye movements (catch-up saccades) compensate for the deficient VOR response during the HIT. These corrective eye movements appear as spikes that occur during the head movement (“covert” saccades) and afterwards (“overt” saccades). Note that the testing is performed sequentially, so some differences may be real; others, however, may be artifactual (e.g., iPhone “wiggly” eye traces from 100–200 ms, likely from noisy measurement). HIT, head impulse test; VOR, vestibulo-ocular reflex.