
Premium content
Access to this content requires a subscription. You must be a premium user to view this content.

poster
Novel Ambulatory Event Capture Device: Characterization of Non-Pathologic Nystagmus
Introduction: The objective is to develop a proof-of-concept smartphone-based eye-tracking algorithm to assess non-pathologic optokinetic (OKN) nystagmus in healthy participants. Current videonystagmography (VNG) is typically restricted to in-office use, and advances in ambulatory or portable vestibular diagnostic devices would yield immense public health benefits.
Methods: Healthy participants (n=39) without a history of dizziness or vertigo were recruited for this prospective comparison study. A smartphone attached to a custom head stabilization device illuminated by a white LED circuit was used to record nystagmus induced with a 30 frames/sec OKN stimulus over a 30-second period. A centroid tracking algorithm ("VertiScope") was created and optimized to detect slow-phase velocity (SPV) of horizontal nystagmus in a diverse subject cohort in a variety of lighting conditions. A cohort of subjects measured in ideal lighting conditions (n=16) underwent standard VNG for comparison of nystagmus recordings with our novel VertiScope algorithm.
Results: Non-pathologic nystagmus was measured across multiple lighting conditions, with high signal-to-noise ratios (SNR) and mean SPV of 22.53+/-5.16 deg/sec. Nystagmus SPV was not significantly different between the device and standard VNG system (t= -0.5, p=0.6). Lighting conditions produced SNRs of 49.28 (dark), 48.90 (backlit), 51.33 (side-lit), 55.65 (outdoor lighting), and 58.42 (ideal). VertiScope SPV was not significantly different when compared against quantitative facial metrics for all participants.
Conclusions: Here, we demonstrate the feasibility of a novel oculography device and in the detection of non-pathologic nystagmus in healthy subjects. Future applications of this device include: obtaining real-time measurements of nystagmus during an acute vertigo attack in patients with vestibular disorders; testing patients unable or unwilling to present to a specialized vestibular laboratory; efficiently repeating testing overtime; and improving accessibility of vestibular testing.