Patients with chronic bilateral vestibular hypofunction may suffer from a visual instability during head movement called oscillopsia. Visual consequence of vestibular deficit can lead to a severe impairment of their quality of life. However, correcting saccades during rapid head movement, called covert-saccades, have been more recently identified. These saccades, which occur during the head movement in patients with vestibular hypofunction, present a very short latency. They could compensate for the lack of vestibular-ocular reflex and greatly decrease oscillopsia and visual impairment. The objective of this study is to evaluate the potential functional benefice of these compensatory movements in a population of 20 patients with chronic bilateral areflexia, in a cross-sectional study.

Inclusion Criteria:

• Bilateral Vestibular Hypofunction (BVH) with at least two of the tree following criteria

  • Mean peak slow phase velocity of 5°/s or less in bilateral bithermal (30 and 44°C) caloric irrigations
  • Pathologic Head-impulse test
  • VOR gain of <0.25 on rotatory chair tests

• Disorder present for over 6 month

• Comprehension of the experiments instructions

• Patient consent

Exclusion Criteria:

• Corrected Visual Acuity lower than 5/10
• Other conditions leading to oscillopsia or ataxia
• Oculomotor palsy, ocular instability in primary position
• Cervical rachis pathology with instability
• Cochlear Implants
• Non-stabilized medical disease
• Pregnant women
• Patients under tutelage