Effect of topical Phenylephrine on the upper eyelid crease position.

Phenylephrine test not only affects the eyelid position but also the eyelid crease height. We show a significative decrease in eyelid crease height to a symmetrical level with the contralateral lid in all patients that had a positive Phenylephrine test result. This effect is probably due to a posterior lamella shortening secondary to Müller's muscle contraction and suggests that the eyelid crease is not only determined by the projections of levator aponeurosis, but also by the entire force vector of the upper eyelid retractors.