[Measurement of spontaneous blinks with a high-speed blink analyzing system]

In order to analyze spontaneous blink kinematics easily and circumstantially, we developed a new method using an intelligent vision system (IVS) camera with a 1 KHz sampling rate, and evaluated the efficacy of this system.

Eleven healthy male volunteers were examined after obtaining informed consent. Eyelid movements in the primary eye position were recorded with an IVS camera twice, for 30 seconds each. Data of upper lid position and lid movement were plotted every 1 msec by image processing of the recorded images. Thereafter blink duration and maximum blink velocity in every spontaneous blink were calculated.

Thirty-nine instances of complete lid-closure type and seventy of incomplete lid-closure type of spontaneous blinks were observed. The average duration of the down-phase, the up-phase, and the total blink were the same for both types; about 100 msec., 220 msec., and 320 msec. respectively. The average down-phase maximum velocity was about 180 mm/sec. in complete lid-closures and 120 mm/sec. in incomplete lid-closures. The average up-phase maximum velocity was about 60 mm/sec. in complete lid-closures and 45 mm/sec. in incomplete lid-closures. Blink amplitude and the maximum velocity achieved during lid closing and opening were strongly correlated and exhibited a linear relationship (r = 0.85, r = 0.73 p < 0.0001).

This new, non-invasive system is an easy to use measuring method for blink kinematics and is highly reliable and very useful.