Videonystagmography to assess blinking

Background In order to measure blinking, we developped a dynamic device consisting of a CCD camera connected to a videonystagmography machine. We developed an artificial pupil that allowed the camera to track movements of the upper eyelid. Methods Blinking parameters were measured in eight healthy volunteers, studying spontaneous blinking (SB) and voluntary blinking (VB) responses. Closing time, opening time, closing speed, vertical amplitude, horizontal amplitude and frequency of spontaneous blinking were recorded. Results In SB, opening time (0.21 +/- 0.04 s) was significantly longer than closing time (0.10 +/- 0.02 s) (< 0.0001). Mean closing speed was 87 +/- 26 m/s in SB and 168 +/- 59 m/s in VB. Mean vertical amplitude was 9.1 +/- 2.2 mm. Mean vertical amplitude was lower in SB (9.1 +/- 2.2 mm) than in VB (12.3 +/- 1.9 mm) (< 0.001). Mean horizontal amplitude was also lower in SB (2.7 +/- 0.9 mm) than in VB (3.8 +/- 0.9 mm) (< 0.05). Frequency of SB was 18.4 +/- 3.4 per minute. Conclusions Computer-assisted video acquisition provides real-time measurement of eyeblink dynamics. On healthy volunteers, this method enables accurate measurement of opening and closing responses as well as associated horizontal movement, and enables differentiating spontaneous and voluntary blinking.