2.1. Study Design
headaches
A prospective single-centre randomized, double-blind, controlled trial investigated eyebrow position, electrical activity of the upper facial muscles, and headaches after upper blepharoplasties. The study protocol was approved by the institutional review board (METc2017/451), following the Declaration of Helsinki Ethical Principles for Medical Research Involving Human Subjects, and was registered in the Netherlands Trial Register (ID NL7886). Written informed consent was obtained from all the study participants.