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 drug on blinking. The authors show that ocular instillation of phenylephrine, 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 alternating current which is amplified and used to display the position of the upper eyelid in degrees on the ordinate of a graph with time in milliseconds on the abscissa. The graph is called a blepharogram. Blepharogram studies and individual blink analysis show the effect of phenylephrine on eyelid motion (blinking). Results: Instillation of phenylephrine accelerated the up phase of the blink in ail ten experimental subjects. 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 eyelid motion. The blepharogram technique provides insight into eyelid physiology and can be used to study any neuromuscular condition that affects eyelid motion.