Conjunctivitis

Conjunctivitis is inflammation of the conjunctiva, the thin transparent membrane that covers the white of the eye and the inner surface of the eyelids. When this membrane becomes inflamed, the small blood vessels within it dilate, causing the eye to appear red or pink. It is one of the most common eye conditions in the world.

Common symptoms include redness of the eye, a gritty sensation, tearing, itching, and discharge that sometimes crusts the eyelids during sleep. Vision is usually not significantly affected, but if vision deteriorates or severe pain and light sensitivity develop, this suggests that the infection has spread to other structures such as the cornea (the clear front part of the eye).

Types and causes

Conjunctivitis is classified according to its cause. Viral conjunctivitis typically accompanies a cold or flu, and its discharge is watery and spreads easily. Bacterial conjunctivitis produces a thick discharge that is yellow or greenish. Allergic conjunctivitis results from pollen, dust, or mites, usually affects both eyes, and is accompanied by intense itching. There is also conjunctivitis caused by chemical irritants, smoke, or contaminated water.

Transmission and prevention

Viral and bacterial conjunctivitis spread through direct contact—touching the eye with contaminated hands, towels, bedding, or shared eye makeup or equipment. For this reason, regular and thorough hand washing with soap, avoiding rubbing the eyes hard, and not sharing towels are the most important preventive measures. Children at school are sometimes advised to remain home until the discharge resolves.

Diagnosis and treatment

Diagnosis is made through medical examination and patient history; an eye care instrument is used to ensure the cornea is unharmed. Occasionally, a sample of the discharge is examined under a microscope. Viral conjunctivitis typically resolves on its own within a week or two, and treatment involves eye irrigation, cleaning, and artificial tears to reduce discomfort. Bacterial conjunctivitis responds to antibiotic medications, either as drops or ointment. Allergic conjunctivitis is managed with antihistamine medications and avoidance of the allergen.