Objective: While vocal fold vibration along the medial surface plays an important role in voice production, its visualization is often difficult from a superior view using endoscopy. This study aims to investigate three-dimensional vocal fold vibration dynamics in the coronal plane in healthy volunteers using optical coherence tomography (OCT) imaging to provide a more quantitative assessment of vocal fold biomechanics and identify potential gender differences in vocal fold vibration.

Methods / Design: Twelve participants (1:1 male to female ratio) underwent awake, transoral imaging using a custom-built, hand-held swept-source rigid laryngoscope equipped with optical coherence tomography (OCT) technology housed in a 3D-printed body. Phonation was captured during sustained vowel /i/ production at modal pitch in each healthy volunteer. A novel algorithm was employed to reconstruct the vocal fold vibratory cycle in the coronal plane from the OCT data. Six dynamic metrics were extracted from each video reconstruction, including: closed quotient; angle at closure; medial surface vertical thickness; vertical displacement; mucosal peak; and amplitude of lateral excursion. Data were categorized by gender, and applicable metrics were stratified into right vocal fold (RVF) and left vocal fold (LVF) regions. Independent t-tests were performed to assess gender differences for each metric.

Results: Closed quotient, angle at closure, medial surface vertical thickness, vertical displacement, mucosal peak, and amplitude of lateral excursion could be successfully extracted and measured from OCT data in all subjects. Significant gender differences were found in vocal fold medial surface vertical thickness (p = 0.015), with males exhibiting consistently greater vertical thickness than females. No significant gender differences were detected in closed quotient, angle at closure, vertical displacement, mucosal peak, and amplitude of lateral excursion in either vocal fold region.

Conclusions: OCT imaging of the vocal folds can be successfully performed in normal subjects during phonation to visualize vocal fold vibration and sub-surface anatomy in the coronal plane.