A computer analysis of reflex eyelid motion in normal subjects and in facial neuropathy

Objective. To demonstrate how computerized eyelid motion analysis can quantify the human reflex blink. Design. Seventeen normal subjects and 10 patients with unilateral facial nerve paralysis were analyzed. Background. Eyelid closure is currently evaluated by systems primarily designed to assess lower/midfacial movements. The methods are subjective, difficult to reproduce, and measure only volitional closure. Reflex closure is responsible for eye hydration, and its evaluation demands dynamic analysis. Methods. A 60Hz video camera incorporated into a helmet was used to analyze blinking. Reflective markers on the forehead and eyelids allowed for the dynamic measurement of the reflex blink. Eyelid displacement, velocity and acceleration were calculated. The degree of synchrony between bilateral blinks was also determined. Results. This study demonstrates that video motion analysis can describe normal and altered eyelid motions in a quantifiable manner. Conclusions. To our knowledge, this is the first study to measure dynamic reflex blinks. Eyelid closure may now be evaluated in kinematic terms. This technique could increase understanding of eyelid motion and permit more accurate evaluation of eyelid function. Dynamic eyelid evaluation has immediate applications in the treatment of facial palsy affecting the reflex blink.