Anatomy of the eye lid

An eyelid is a thin skin fold that covers and protects the anterior aspect of the eye ball.

Parts of the eye lid

Horizontal furrow/sulcus is a horizontal groove dividing the eye lid into orbital part(overlying the bonny socket) and tarsal part (overlying the anterior eye ball).

Palpebral aperture is an elliptical space between the upper and lower eye lid. It measures 10-11mm vertically at the centre and about 28-30mm horizontally with an eye open.

Canthi are two peripheral points at which the upper and lower eye lids meet, with medial canthus being about 2mm higher than lateral canthus.

The eye lid margins forming a junction between the skin layer and palpebral conjunctiva. The Anterior eye lid margin contains lines of eye lashes whereby Posterior eye lid margin contain lines of Meibomian gland orifices.

Layers of the eyelid

Skin and subcutaneous tissue, superficial layer with the subcutaneous tissue lacking fat.

Orbicularis oculi, consisting of the concentric bands of muscle surrounding the eyelid. It has the following parts:

• Palpebral part located over the tarsal plate which gently closes the eyelids.
• Lacrimal part located over the lacrimal apparatus which is involved in the drainage of tears.
• Orbital part located over the orbit which tightly closes the eyelids.

Tarsal plates are dense connective tissue providing mechanical support to each eyelid. They contain Meibomian glands which open into posterior eye ld margin.

Levator apparatus are extra ocular muscles located only on the upper eye lid consisting of levator palpebrae superioris and superior tarsal muscles which facilitate opening of the eyelids.

Palpebral Conjunctiva is a part that forms the inner most lining of the eyelid.