The effect of eye opening and closing on the result of facial wrinkle assessment.

Background/purpose: Since there is no standard protocol that specifies the opening or closing of eyelids in wrinkle assessment, the eyelid position of subjects at the time of assessment varies from study to study. This study aimed to reveal the effect of eye opening and closing on the result of wrinkle assessment. The study also attempted to analyze the age-, site-, and ethnicity-dependent variations in the effect.