title: A new gyro-based method for quantifying eyelid motion.
abstract: OBJECTIVE
  We present an innovative method to quantify the eyeblink by using a miniature gyroscopic sensor (gyro), which is applied on the upper eyelid. Electrical Stimulation (ES) of the facial nerve is a promising technology to treat dysfunctional eyelid closure following facial paralysis. We used the new gyro-based method to evaluate the biomechanics of both the spontaneous and the ES-induced eyeblink, and to identify the best ES protocol.
  
  
  METHODS
  During blinking, eyelids rotate about the axis passing through the eye canthi, thus we propose to use a gyro for measuring the angular velocity of the upper eyelid (ωe  ). The angular displacement of the eyelid (θe  ) was calculated by integrating the ωe signal. Two indices were derived from θe: 1) the eyelid angular displacement during eye closure (C), calculated as the peak value of θe ; 2) the eyelid closure duration (D), calculated as the time interval between zero signal and the peak value of θe. In a healthy volunteer we used this method to quantify both the spontaneous eyeblink and the blinks elicited by different ES patterns.
  
  
  RESULTS
  For the spontaneous eyeblink, indices C = 14.0 ± 1.8° and D = 94.0 ± 10.8 ms were computed. By comparing C and D indices for spontaneous and ES cases, trains of 10 pulses with a frequency ranging from 200 Hz to 400 Hz proved to induce the most effective and natural-like eyeblinks.
  
  
  CONCLUSIONS
  The new gyro-based method proved to be a valuable tool to provide dynamic and real-time quantification of eyelid motions. It could be particularly useful for evaluating the effective and natural-like eyeblink restoration provided by ES.
authors: Biomedical Technology Unit, University of Bologna, 40138 Bologna, Italy. emanuela.marcelli@unibo.it
authors: Emanuela
authors: E
authors: Marcelli
authors: Paolo
authors: P
authors: Cavallari
authors: Alice
authors: A
authors: Frigerio
authors: Giacomo
authors: G
authors: Colletti
authors: Federico
authors: F
authors: Biglioli
authors: Roberta
authors: R
authors: Fanti
authors: Gianni
authors: G
authors: Plicchi
authors: Laura
authors: L
authors: Cercenelli
mesh_terms: D001767:Blinking / Q000502:physiology*; D004558:Electric Stimulation; D004576:Electromyography; D005143:Eyelids / Q000503:physiopathology*; D005154:Facial Nerve / Q000503:physiopathology*; D005158:Facial Paralysis / Q000175:diagnosis* / Q000503:physiopathology; D006801:Humans