The Conjunctiva

The inner surfaces of the eyelids and the outer surface of the eyeball are lined by a special type of epithelium, the conjunctiva. This epithelium is a stratified columnar type containing goblet cells, and is partly responsible for producing the moisture that covers the surface of the eye and allows the eyelids to slide open and close easily. The conjunctiva grades into the stratified squamous epithelium of the cornea at the corneal margin, and into the stratified squamous epithelium of the integument at the margins of the eyelids. The portion on the surface of the eyeball is referred to as the bulbar conjunctiva, while that on the inner surfaces of the eyelids is the tarsal conjunctiva.

The bulbar and tarsal conjunctiva are continuous, the one reflecting onto the other at the inner margins of the eyelid. Because the conjunctiva is richly supplied with blood vessels, it can be used as a route of administration for some drugs which are quickly absorbed across moist membranes. Its exposure to the open environment also makes it susceptible to inflammation.

 

















Left: The reflection of the bulbar and tarsal conjunctiva, forming a "pocket" around the eye. Right: Goblet cells in the conjunctival epithelium, whose secretions are important in keeping the eye moist.