Detection of VOR dysfunction during the gaze stabilization test: Does target size matter?

Area of Science:

• Ophthalmology
• Neurology
• Vestibular System

Background:

• The Gaze Stabilization Test (GST) assesses vestibulo-ocular reflex (VOR) dysfunction by measuring target recognition decline with head velocity.
• Optimal optotype size for GST above static visual acuity remains undefined.

Purpose of the Study:

• Determine the optimal optotype size for the GST in individuals with unilateral vestibular dysfunction (UVD) and healthy controls.
• Evaluate optotype sizes 0.2 and 0.3 logMAR above static visual acuity (ΔlogMAR).

Main Methods:

• Eight UVD subjects and 19 healthy controls underwent the standard GST protocol.
• Maximal head velocity during fixation on 0.2 and 0.3 ΔlogMAR optotypes was recorded.
• Sensitivity, specificity, and ROC AUC analyses identified optimal head velocity cutoffs.

Main Results:

• The 0.2 ΔlogMAR optotype showed a significant difference in maximal head velocity between UVD and control groups (p=0.032).
• 0.2 ΔlogMAR yielded higher sensitivity (75% vs. 63%) and accuracy (86% vs. 80%) in detecting UVD.
• Positive likelihood ratios were substantially higher for 0.2 ΔlogMAR (10) compared to 0.3 ΔlogMAR (6.3).

Conclusions:

• The 0.2 ΔlogMAR optotype is significantly more effective for identifying UVD and detecting VOR dysfunction.
• Using 0.2 ΔlogMAR during GST may improve VOR dysfunction detection and serve as a baseline for rehabilitation therapy.