The photon-counting pulses generated by the APD are fed to a photon-counting board of a RHK controller (RHK Technology) system for time-intermittency PL (or blinking) measurement.
As an example, driver head localisation, point of gaze detection and eye blink rate measurement is considered for which the design of a dash-board-mountable automotive stereovision camera system is presented.
The Optalert system allows for measurements of blink duration and eye closure time [ 18, 25].
Repeated measurement analysis was performed on blink frequency (60 consecutive measurements of 2 min each) and one questionnaire with 10 questions was administered at six different times.
Eye-blink and saccade measurement, for instance, is one of the techniques that may be employed to measure a driver's state of vigilance and to detect the onset of sleep [10, 16].
For this subject, there were no blinks during the measurement without and with the scleral lens.
Measurements that were contaminated by patient blinking or unstable fixation were excluded, and one non-contaminated measurement for each eye was used in the final analysis.
Both tests were assessed after asking the subjects to blink a couple times and the measurements were performed three times to obtain a more reliable value.
The tear film was measured for 6 s after a complete blink, using a short measurement time to avoid reflex tearing.
Subjects were asked to blink prior to the measurement.
