The Anatomy of the Conjunctiva

The clear tissue covering the white of the eyes protects the eye

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The conjunctiva is the clear tissue that covers the white part of the eye and the inside of the eyelids. A healthy conjunctiva is necessary for the eye to function normally, as it helps to create a suitable environment for the cornea, which is responsible for focusing most of the light that enters the eye. It helps protect the eye by keeping out foreign objects and microorganisms. It also helps maintain the tear film.

Anatomy

The conjunctiva is divided into three segments: the bulbar conjunctiva, the palpebral conjunctiva, and the fornix conjunctiva.

The bulbar conjunctiva covers the anterior part of the sclera (the white of the eye). It does not cover the cornea.

The palpebral conjunctiva covers the inner surface of the upper and lower eyelids. The bulbar and palpebral conjunctiva are both continuous, making it impossible to lose a contact lens behind your eye.

The fornix conjunctiva forms the junction between the bulbar and palpebral conjunctivas. Its flexibility allowing the eyelids and eyeball to move freely.

Function

The primary function of the conjunctiva is to keep the front surface of the eye moist and lubricated. It also keeps the inner surface of the eyelids moist and lubricated, making them able to open and close easily without causing eye irritation. Another job of the conjunctiva is to protect the eye from dust, debris, and microorganisms that could cause infection.

Because it contains many small blood vessels, the conjunctiva is able to provide important nutrients to the eye and eyelids. It also contains special cells that work with the tear film to help prevent dry eye syndrome.

Associated Conditions

Several conditions can affect the normal functioning of the conjunctiva. Because the surface of the eye is exposed, it is susceptible to many problems including infection, trauma, allergic reactions, and dryness. Following are common conjunctival disorders:

Conjunctivitis

Conjunctivitis, also known as pink eye , is inflammation or infection of the conjunctiva. Some forms (bacterial, viral) are highly contagious. Other forms may be triggered by an allergy or exposure to harsh chemicals. Symptoms can be persistent and include redness, itching, tearing, discharge, and more.

Injected Conjunctiva

Injected conjunctiva is bloodshot eyes. The eyes appear red because of the dilation of blood vessels in the conjunctiva. Bloodshot eyes can be caused by dry air, sun exposure, dust, foreign body, allergies, infection, or trauma. Symptoms can include redness, pain, burning, and itching.

Conjunctival Hemorrhage

A subconjunctival hemorrhage is bleeding of the eye. Bleeding inside the eye can result in a tiny speck of redness or a large area of red blood. If you have ever experienced a subconjunctival hemorrhage, you know that the condition can be alarming. The hemorrhage will look like a patch of bright, red blood on the white part of your eye. A subconjunctival hemorrhage is usually harmless, with the visible blood resulting from a simple broken blood vessel. 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 usually resolves on its own within a couple weeks.

Conjunctival Lymphoma

A conjunctival lymphoma is a tumor that usually appears as a painless, salmon-pink, “fleshy” patch on the eye. Conjunctival lymphomas are usually hidden behind the eyelids and are painless. They are typically discovered during a routine comprehensive eye exam. If you notice a growth on your eye, immediately see an ophthalmologist. A biopsy will determine the proper treatment.

Conjunctival Hemangioma

A conjunctival hemangioma is a congenital malformation of a clump of blood vessels that develops on the white part of the eye. A conjunctival hemangioma is usually benign, but should be examined annually. If a patient desires, it can be surgically removed for cosmetic reasons or if it causes irritation.

Conjunctivochalasis

Conjunctivochalasis (CCh) is a common age-related disorder of the conjunctiva. It is characterized by the presence of folds of the conjunctiva that typically develop between the eyeball and the eyelids. The folds are commonly found along the lower lid margin and interfere with the normal distribution of tears. The condition may lead to dry eye disease. Treatment may include tear substitutes, lubricants, corticosteroids or antihistamine drops. For more advanced symptoms, treatment may involve surgical conjunctival resection and amniotic membrane transplantation.

Chemosis

Sometimes the conjunctiva becomes inflamed and swollen. This condition is referred to as chemosis. Symptoms include watery eyes, excessive tearing, eye itchiness, and double or blurred vision. The following are some of the most common causes of chemosis:

  • Allergies: Irritation is the primary cause of chemosis. Many people suffer from seasonal allergies or allergic reactions to pets, and often develop eye irritation. Animal dander and pollen can make your eyes water, appear red, or develop a discharge. This condition is called allergic conjunctivitis.
  • Infections: Bacterial or viral infections often lead to conjunctivitis. These infections can make the eyes red, itchy, and watery. Although the infections are contagious, the actual symptoms of chemosis cannot be transmitted alone.
  • Eye surgeries: Surgery to the eyes or eyelids often leads to the development of chemosis. Symptoms typically only last a couple of days and are treated with eye drops, cold compresses, or temporary eye patching.
  • Hyperthyroidism: Hyperthyroidism is a disorder of the thyroid gland that leads to the overproduction of hormones in the thyroid. This condition can cause chemosis and also lead to eye problems such as bulging of the eyes, eye puffiness, and retraction of the eyelids.
  • Excessive rubbing: Simply touching, rubbing, or scratching the eyes is a common cause of chemosis. Rubbing the eyes is discouraged as doing so will increase irritation and possibly cause eye damage.

Treatment for chemosis depends on the cause but eye doctors generally recommend the lubricating eye drops, cold compresses, eye patching, corticosteroids, anti-inflammatory medications, antihistamines, adrenaline or epinephrine, or antibiotics. Conjunctivoplasty is another treatment option that involves making a small incision into the conjunctiva and then removing the excess membrane. This procedure may be recommended in cases of prolonged swelling and irritation.

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Additional Reading
  • Kanski, Jack J, and Brad Bowling. Clinical Ophthalmology—A Systematic Approach. Seventh Edition. Elsevier Saunders, 2011.