The authors of this article thoroughly explain the anatomical basis of upper eyelid asymmetry and the impact it may have on blepharoplasty. The eyelid is divided into three different areas (brow fat span, tarsal plate show and margin reflex distance) in order to measure and characterise the key contours. The presence of eyelid ptosis will reduce the margin reflex distance and increase both the tarsal plate show and the brow fat span; ptosis repair normalises these parameters and may sometimes spare skin resection in the upper eyelid. In case of symmetrical tarsal plate show and unilateral eyelid ptosis, asymmetrical skin resection of the upper lid will be necessary to achieve symmetry. The authors advocate for the posterior approach Müller muscle conjunctival resection for the treatment of minor ptosis (up to 2mm). Eyebrow asymmetry will normally improve with ptosis repair; contralateral ptosis may appear after unilateral ptosis treatment. This is a very interesting article for any surgeon with an oculoplastic practice.