THE EFFECT OF PHENYLEPHRINE ON MULLER MUSCLE - A BLEPHAROGRAM STUDY OF EYELID MOTION

Purpose: The blepharogram technique is used to study the effect of a d rug on blinking. The authors show that ocular instillation of phenylep hrine, a stimulant of Muller muscle of the eyelid, accelerates the up phase of the blink. Methods: Motion of a tiny search coil glued to the eyelid moving in a weak magnetic field modifies an induced alternatin g current which is amplified and used to display the position of the u pper eyelid in degrees on the ordinate of a graph with time in millise conds on the abscissa. The graph is called a blepharogram. Blepharogra m studies and individual blink analysis show the effect of phenylephri ne on eyelid motion (blinking). Results: Instillation of phenylephrine accelerated the up phase of the blink in ail ten experimental subject s. In 65% of subjects, phenylephrine also produced or increased newly described N and M blepharogram patterns. Conclusion: This is the first instrumental detection of the effect of a pharmacologic agent on eyel id motion. The blepharogram technique provides insight into eyelid phy siology and can be used to study any neuromuscular condition that affe cts eyelid motion.