Convergence vestibulo-ocular reflex in unilateral vestibular hypofunction: Behavioral evidence in support of a novel gaze stability exercise

Tzu Pu Chang, Michael C. Schubert

Research output: Contribution to journalArticlepeer-review


Background and Purpose: Convergence of the eyes during head rotation increases the gain (eye velocity/head velocity) of the vestibuloocular reflex (VOR). We sought to know whether convergence would increase the VOR gain (mean + SD) in unilateral vestibular hypofunction (UVH).

Methods: Vestibulo-ocular reflex gain during ipsi- and contralesional horizontal head rotation at near (15 cm) and far (150 cm) targets was measured in 22 subjects with UVH and 12 healthy controls. Retinal slip was estimated (retinal slip index [RSI]) as the difference between ideal VOR gain (no retinal slip) and the actual VOR gain.

Results: Convergence did not significantly enhance VOR gain for ipsilesional rotation (mean difference, 0.04; 95% confidence interval [CI], −0.01 to 0.09), near viewing (0.77 ± 0.34) versus far viewing (0.72 ± 0.29), yet the VOR gain during contralesional rotation was greater for near viewing (1.20 ± 0.23) than for far viewing (0.97 ± 0.21; mean difference, 0.23; 95% CI, 0.13-0.32). In the 36% of subjects with recovery of their ipsilesional VOR gain, the vergence effect trended to recover (far VOR gain: 1.06 ± 0.17 vs near VOR gain 1.16 ± 0.21; mean difference, 0.10; 95% CI, −0.02 to 0.22). Ipsilesional head rotation induced greater retinal slip for near (RSI = 0.90 ± 0.34) targets than for far targets (RSI = 0.35 ± 0.29; mean difference, 0.56; 95% CI, 0.51-0.61).

Discussion and Conclusions: The convergence-mediated VOR gain enhancement is preserved during contralesional but impaired during ipsilesional head rotation. Recovery of ipsilesional passive VOR gain does not equate to restored convergence enhancement, although it did increase ∼10%. These data suggest head motion viewing near targets will increase retinal slip, which warrants consideration as a gaze stability exercise for subjects with UVH.

Original languageEnglish (US)
Pages (from-to)3-11
Number of pages9
JournalJournal of Neurologic Physical Therapy
Issue number1
StatePublished - Jan 2021


  • Convergence
  • Gaze stability
  • VOR
  • Vestibular hypofunction
  • Video head impulse test

ASJC Scopus subject areas

  • Physical Therapy, Sports Therapy and Rehabilitation
  • Rehabilitation
  • Clinical Neurology


Dive into the research topics of 'Convergence vestibulo-ocular reflex in unilateral vestibular hypofunction: Behavioral evidence in support of a novel gaze stability exercise'. Together they form a unique fingerprint.

Cite this