Continuing with our series on the function of the eye we will move on to the conjunctiva. The conjunctiva is the clear, thin membrane that covers part of the front surface of the eye and the inner surface of the eyelids and has two segments.
Bulbar conjunctiva. This section of the conjunctiva covers the anterior part of the sclera (or the “white” of the eye). The bulbar conjunctiva stops at the junction between the sclera and cornea and it does not cover the cornea.
Palpebral conjunctiva. This section covers the inner surface of both the upper and lower eyelids. The bulbar and palpebral conjunctiva are continuous and thanks to that feature it is impossible for a contact lens (or anything else) to get lost behind your eye.
The primary functions of the conjunctiva are:
- Keeping the front surface of the eye moist and lubricated.
- Keeping the inner surface of the eyelids moist and lubricated so they open and close easily without friction or causing eye irritation.
- Protecting the eye from dust, debris and infection-causing microorganisms.
The conjunctiva has many small blood vessels that provide nutrients to the eye and lids. It also contains special cells that secrete a component of the tear film to help prevent dry eye syndrome.
A number of conditions can affect the conjunctiva. Among the more commonly known conjunctival problems are:
Conjunctivitis. Also called pink eye, this is inflammation of the conjunctiva. It can have several causes.
Injected conjunctiva. This is a red eye caused by dilation of blood vessels in the conjunctiva. It can have many causes.
Conjunctival hemorrhage. This is bleeding from a small blood vessel on the front surface of the eye, over the sclera. Because the leaking blood spreads out under the conjunctiva, it causes the white of the eye to appear bright red. More accurately called a subconjunctival hemorrhage, this type of red eye is harmless and typically resolves on its own within a couple weeks.
Conjunctival lymphoma. This is a tumor of the front surface of the eye that usually appears as a salmon-pink, “fleshy” patch. Conjunctival lymphomas typically are hidden behind the eyelids and painless; therefore they may be present for quite some time before they are discovered — especially in people who don’t have routine comprehensive eye exams. If you have a growth on your eye that resembles this description of a conjunctival lymphoma, immediately see an ophthalmologist who can evaluate it and perhaps perform a biopsy to determine the proper treatment.
Conjunctival hemangioma. This is a benign (noncancerous) tumor of tiny blood vessels that creates a red, blood-filled sac in the conjunctiva. Large conjunctival hemangiomas can be surgically removed if they cause irritation.
For more information on how other parts of the eye works be sure to check out our other articles available on Schmidt’s Optical and Hearing™.