Anatomy & Education
Eyelid Anatomy
Eyelid Anatomy
The eyelid is a remarkably complex structure — five distinct tissue layers work together to protect the eye, distribute the tear film, and regulate the amount of light entering. Understanding this anatomy is the foundation for all oculoplastic procedures.
Overview
Each eye is protected by upper and lower eyelids (palpebrae). The eyelids meet at two corners — the medial canthus (near the nose) and the lateral canthus (toward the temple). The free margin of each lid is approximately 30 mm long and carries two to three rows of lashes (cilia).
The upper eyelid normally rests 1–2 mm below the superior limbus of the cornea. The lower lid rests at or just above the inferior limbus. Any deviation from these positions — whether drooping, turning in, or turning out — is a surgical indication that oculoplastic surgeons are trained to correct.
Eyelid Layers
From anterior (front) to posterior (back), the eyelid consists of five layers:
- 1Skin
The thinnest skin in the body — typically 0.5–1 mm. It contains fine hair follicles and sebaceous glands, and becomes redundant with age, contributing to dermatochalasis (hooded lids).
- 2Orbicularis Oculi
A circular muscle responsible for eyelid closure. The orbital portion closes forcefully (blink, squint); the preseptal and pretarsal portions perform gentle, reflex blinking. Paralysis of this muscle — as in facial nerve palsy — causes lagophthalmos (inability to close the eye).