Related Experiment Videos
Vertical dynamic visual acuity in normal subjects and patients with vestibular hypofunction
Michael C Schubert1, Susan J Herdman, Ronald J Tusa
1Department of Rehabilitation Medicine, Emory University, 1441 Clifton Road NE, Atlanta, GA 30322, U.S.A. michael_schubert@emory.org
Summary
A new test reliably measures visual acuity during active vertical head movement. However, this measure did not correlate with subjective oscillopsia reports, suggesting movement predictability plays a role.
Area of Science:
- Ophthalmology
- Neuroscience
- Vestibular Science
Background:
- Oscillopsia, the sensation of visual instability, significantly impacts quality of life.
- Assessing visual acuity during head movements is crucial for understanding vestibular and visual system interactions.
- Current methods for evaluating oscillopsia lack objective measures during dynamic tasks.
Purpose of the Study:
- To evaluate the reliability and diagnostic accuracy of a novel computerized test measuring visual acuity during active vertical head movement.
- To investigate the relationship between objective measures of visual acuity during head movement and subjective reports of oscillopsia.
Main Methods:
- A prospective, clinical study was conducted in a tertiary referral center.
- Participants included normal subjects and patients with various vestibular disorders (unilateral/bilateral vestibular hypofunction, nonvestibular dizziness).
- Visual acuity during active vertical head movement was measured using a computerized test; oscillopsia was assessed via a visual analog scale.
Main Results:
- The active vertical head movement test demonstrated high reliability in both normal subjects (ICC=0.89) and patients (ICC=0.94).
- Age significantly affected head movement performance, with older individuals exhibiting reduced visual acuity during movement.
- Subjective oscillopsia reports did not correlate with objective measures of visual acuity during the active head movement test.
Conclusions:
- The computerized active vertical head movement test is a reliable tool for assessing visual acuity during dynamic head motion.
- Age-related decline in neuronal function may contribute to reduced performance on this test.
- The lack of correlation between objective and subjective measures may stem from the predictable nature of the test movements versus real-world scenarios like walking.