Characterization of Optokinetic Nystagmus in Healthy Participants With a Novel Oculography Device

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 portable vestibular diagnostics would yield immense public health benefits.

Methods: Healthy participants (n=30) 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 60-second period. A centroid tracking algorithm was created and optimized to detect slow-phase velocity (SPV) of horizontal nystagmus in a diverse subject cohort in a variety of lighting conditions. Nystagmus recordings were compared to those obtained from a standard Neurokinetics VNG system.

Results: Non-pathologic nystagmus was measured across multiple lighting conditions, with high signal-to-noise ratios (SNR) and mean SPV of 25.3+6.7 deg/s. Nystagmus SPV was not significantly different between the device and standard VNG system (t= -0.5, p=0.6). Non-ideal lighting conditions produced SNRs of 2.2 (dark), 43.3 (backlit), 90.4 (side-lit), 98.6 (outdoor lighting), and 116.7 (fluorescent).

Conclusions: Here, we demonstrate the feasibility of a novel oculography device 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.