There are multiple definitions:

1. vestibulo-ocular reflex(English)

   • its gain is defined as the instantaneous eye velocity divided by inverted head velocity
   • CANVAS, VVOR, aUVL, GEN, HIT, NHP, SP, VN, DVA, GST, NVD, VSVOR, VSR, VCR
   • Neurology, Ophthalmology, Reflex
   • https://doi.org…000000000000215
   • https://doi.org…000000000003316
   • https://doi.org…res.2006.02.008
   • https://doi.org…2/jn.00626.2015

2. vestibulo-ocular response(English)

   • calculated as the ratio of the area under the eye velocity curve, to the area under the head velocity curve, during the head impulse. Normal VOR gain is close to 1.0. Patients with unilateral vestibular loss (UVL) have a reduced VOR gain during the head turn to their affected ear (usually less than 0.7) and so their slow phases do not compensate for head turn, with the result that their eyes move with the head, and they need to make corrective saccades for head impulses toward their affected ear, thus identifying the side of loss
   • UVL, BVL
   • Ratio-based metric, Ophthalmology, Reflex
   • https://doi.org…neur.2017.00258