The lower eyelid is composed of very thin skin, a small tarsal plate, and muscles that close (protractors) and open (retractors) the lid. The shape of the lower eyelid is determined by the attachment of the medial and lateral canthal tendons as well as the tone and contraction of the OOM. The lateral canthal angle is usually positioned 1 to 2 mm above the medial canthal angle. The infratarsal crease of the lower eyelid is variable, but is often most noticeable at the inferior border of the short lower eyelid tarsal plate.
