M.W. Johns, A.J. Tucker. The Amplitude-Velocity Ratios for Eyelid Movements During Blinks: Changes with Drowsiness.
Introduction
The ratio of amplitude to maximum velocity (AVR) of eyelid closure during blinks has previously been shown to increase with drowsiness and to predict lapses in performance of a vigilance task (Johns, 2003). At that time, the AVR was calculated as the change of position of the eyelids during a blink, from eyelids open to eyelids closed, in uncalibrated units (A), divided by the maximum change of position (delta-A) per 10 msec. These two variables are known to be highly correlated in alert subjects (Evinger et al, 1991). Their ratio (AVR) has the dimension of time. This gives a measure of the relative velocity of eyelid movements which does not depend on calibration of the measurements of amplitude or velocity in absolute units (e.g., mm and mm/sec), so long as those measurements for each movement are made at the same time and under the same circumstances.
AVRs for eyelid movements show promise as a method for monitoring and quantifying the drowsy state.
