Early Ocular Response to Visual Motion in Patients With Persistent Postural-Perceptual Dizziness

Area of Science:

• Neuroscience
• Ophthalmology
• Vestibular Science

Background:

• Persistent postural-perceptual dizziness (PPPD) is linked to visual dependency and altered responses to visual motion.
• Oculomotor responses are crucial for maintaining stable vision during self-motion or environmental motion.

Purpose of the Study:

• To investigate early eye movement responses, specifically ocular following responses (OFRs), to large-field visual motion in PPPD patients.
• To compare OFRs and suppression efficacy between PPPD patients and healthy controls across varying visual field stimulation.

Main Methods:

• Recorded eye movements in 30 PPPD patients and 29 healthy controls viewing horizontal motion stimuli.
• Analyzed OFR velocity and suppression efficacy across different central visual field sizes (5° to 42° radius).
• Assessed visual dependency using the dynamic subjective visual vertical.

Main Results:

• Both groups showed robust OFRs to central visual motion, increasing with stimulus size.
• PPPD patients exhibited significantly higher eye velocity than controls when the central visual field was stationary and the periphery moved.
• Healthy controls demonstrated superior suppression of OFRs during peripheral stimulation compared to PPPD patients.

Conclusions:

• PPPD patients show impaired ability to suppress eye movements during peripheral visual motion, leading to increased retinal slip.
• This oculomotor abnormality may exacerbate dizziness and discomfort in visually complex environments for PPPD patients.
• Greater visual dependency in PPPD patients correlated with larger OFR magnitudes.