Conjunctiva of the eye

Conjunctiva definition

An important structure on the surface of the eye is one you can’t easily see — it’s called 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. The anatomy of the conjunctiva has two main segments:

Bulbar conjunctiva – This portion of the conjunctiva covers the anterior part of the sclera (the “white” part of the eye). The bulbar conjunctiva stops at the junction between the sclera and cornea; it does not cover the cornea.

Palpebral conjunctiva – This portion covers the inner surface of both the upper and lower eyelids. (Another term for the palpebral conjunctiva is tarsal conjunctiva.)

The bulbar and palpebral conjunctiva meet and form a small pocket called the conjunctival sac. The folded tissue where they connect is called the conjunctival fornix.

This anatomy forms one continuous lining, which makes it impossible for a contact lens (or anything else) to get lost behind your eye.

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Conjunctiva function

The primary functions of the conjunctiva are:

• Keep the front surface of the eye moist and lubricated.
• Keep the inner surface of the eyelids moist and lubricated so they open and close easily without friction or causing eye irritation.
• Protect 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 called mucin that helps with the prevention of dry eye syndrome.

Conjunctiva problems

A number of disorders can affect the conjunctiva. Among the more common conjunctival problems are:

Conjunctivitis – Sometimes called pink eye, this is inflammation of the conjunctiva. It can have several possible causes, including viruses, bacteria and allergies. The recommended treatments for conjunctivitis (if needed) depend on the type, severity and other factors.

Conjunctival pallor – This is an unhealthy pale appearance to the palpebral conjunctiva that can be a sign of anemia.

Conjunctival injection – This is red eye caused by dilation of blood vessels in the conjunctiva. It can have many causes.

Conjunctival cyst – This is a thin-walled clear sac in the conjunctiva that contains clear fluid. It resembles a small, clear blister on your skin. A conjunctival cyst or sac can occur as a result of an eye infection, inflammation or other 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 usually harmless and typically resolves on its own within a couple weeks.

Conjunctival lymphoma – This is a conjunctival tumor that usually appears as a salmon-pink, “fleshy” patch. Conjunctival lymphomas tend to be 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, it is recommended to see an ophthalmologist or optometrist immediately for a diagnostic evaluation.

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.

Conjunctival nevus – This is a common, benign growth in the bulbar conjunctiva. Research shows that conjunctival nevi (plural of nevus) are the most common growth that occurs on the surface of the eye.

A conjunctival nevus can range in color from yellow to dark brown and can darken or lighten with time. In most cases, no treatment is needed for a conjunctival nevus, but if a nevus is growing in size, it can be surgically removed.

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Conjunctival melanoma – This is an elevated, dark or relatively clear cancerous growth in the bulbar conjunctiva. Conjunctival melanomas are uncommon but are very serious. The cancer cells from a conjunctival melanoma can infiltrate the rest of the eye and spread via the lymphatic system or bloodstream to the lungs, liver, brain and bones.

In some cases, a conjunctival melanoma can arise from a benign conjunctival nevus. To be safe, if you notice any type of growth or dark spot on your eye, or an unusual appearance to your conjunctiva, see your eye doctor immediately for an evaluation.

Conjunctivochalasis – Conjunctivochalasis (CCh) is a condition in which the clear outer layer that covers the white part of the eye (the conjunctiva) loosens, creating wrinkles and folds. This can cause a range of symptoms that include discomfort, dry eyes and blurred vision. It is most commonly found in older populations.

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