Quantitative measurement of upper eyelid movements.

A simple and noncontact method for recording upper eyelid movement by means of a solid state image sensor has been developed. Physiological parameters of blink and lid movements during gaze change were studied in 30 normal subjects. Maximum velocity against lid displacement was analyzed. Electromyography (EMG) of the levator palpebrae as well as orbicularis oculi muscles was conducted and vertical eye movement was recorded by electrooculography (EOG). The maximum lid velocity both for upward and downward gaze change was measured; it was always faster in the downward than in the upward gaze. The duration of lid movement during upward gaze change was about 70 msec longer than that of the vertical saccadic eye movement. By EMG, a pulse-step discharge has been well known to occur in the superior rectus muscle but it was never seen in the levator palpebrae muscle in the present observation. The maximum lid velocity of downward spontaneous blink showed two-phase distributions: phase 1 with an initial flat phase in small displacement and phase 2 with a steep phase in large displacement. By EMG, only the pretarsal portion of the orbicularis muscle discharged at the initial phase; preseptal as well as pretarsal orbicular muscle discharges were noted in the second phase. The simplicity of this technique would permit its wide clinical application.