Oscillopsia in Bilateral Vestibular Hypofunction: Not Only Gain But Saccades Too

Area of Science:

• Neuroscience
• Ophthalmology
• Vestibular System

Background:

• Bilateral vestibular hypofunction (BVH) causes oscillopsia, a disabling visual disturbance.
• The vestibulo-ocular reflex (VOR) impairment in BVH necessitates refixation saccades for head movement compensation.

Purpose of the Study:

• To investigate the relationship between saccadic strategies and the perception of oscillopsia in BVH patients.
• To identify predictors of oscillopsia in individuals with impaired VOR.

Main Methods:

• Patients with BVH were categorized into two groups based on video head impulse test (vHIT) gain values.
• Binary logistic regression (BLR) was employed to identify variables predicting oscillopsia.
• Saccade synchrony was measured using the PR score.

Main Results:

• The PR score, reflecting saccade synchrony, emerged as the strongest predictor of oscillopsia.
• A PR score cutoff of 0.518 demonstrated high diagnostic accuracy (86.6% sensitivity, 84.2% specificity).
• Higher PR values (less synchronized saccades) correlated with increased proneness to oscillopsia.

Conclusions:

• Nonsynchronized saccades, indicated by higher PR scores, are associated with oscillopsia in BVH patients, irrespective of vHIT gain.
• The PR score is proposed as a valuable metric for assessing compensatory mechanisms in BVH.