Conjunctivitis
Inflammation of the conjunctiva causing red or pink eye.
Conjunctivitis, commonly called pink eye, involves inflammation of the conjunctiva, the thin, clear membrane lining the inner eyelids and covering the white part of the eye. This inflammation causes the eye to appear pink or reddish, often accompanied by pain, a burning or scratchy sensation, and itching. The affected eye may water excessively or produce a discharge that can cause the eyelids to stick together, particularly after sleep. Swelling of the sclera may also occur. Itching is more prominent in allergic cases. The condition can affect one or both eyes.
In adults, the most frequent infectious cause is viral, while in children, bacterial infections are more common. Viral conjunctivitis often coincides with symptoms of a common cold, such as a sore throat or upper respiratory infection. Both viral and bacterial forms spread easily among people. Allergies to pollen or animal hair are another frequent cause. Diagnosis is typically based on signs and symptoms; occasionally, a sample of discharge is cultured to identify the pathogen.
Prevention relies partly on handwashing. Treatment depends on the underlying cause. Most viral cases have no specific treatment and resolve on their own. Bacterial infections also often clear without intervention, though antibiotics can shorten the illness. People who wear contact lenses or whose infection stems from gonorrhea or chlamydia require treatment. Allergic conjunctivitis can be managed with antihistamine or mast cell inhibitor eye drops.
In the United States, three to six million people experience acute conjunctivitis annually, typically improving within one to two weeks. If vision loss, significant pain, light sensitivity, signs of herpes, or symptoms persisting beyond a week occur, further evaluation is needed. Newborns with conjunctivitis, known as neonatal conjunctivitis, also require specific treatment.
- field
- Medicine (Ophthalmology)
- known_for
- Inflammation of the conjunctiva causing red or pink eye
- common_causes
- Viral (adenoviruses), bacterial (Staphylococcus, Streptococcus), allergies, chemical irritants
- affected_population
- 3–6 million acute cases per year in the United States
- typical_duration
- 1–2 weeks
Lore & Background
Conjunctivitis is identified by inflammation of the conjunctiva, which manifests as irritation and redness of the eye. The eye appears pink or reddish due to the dilation of small blood vessels. Patients may experience pain, a burning or scratchy sensation, or itchiness; itching is more common in allergic cases. The affected eye may produce excess tears or become stuck shut in the morning, and swelling of the sclera can occur. The condition can affect one or both eyes. Viral conjunctivitis, which accounts for the majority of adult cases, typically presents with a fine, diffuse pinkness and a watery discharge, often accompanied by symptoms of a common cold, sore throat, or pre-auricular lymph node swelling. Microscopic examination may reveal numerous lymphoid follicles on the tarsal conjunctiva and sometimes a punctate keratitis. Bacterial conjunctivitis, more common in children, usually causes a rapid onset of redness, eyelid swelling, and a sticky, opaque discharge that is greyish or yellowish, leading to crusting and lids sticking together; a gritty sensation may be so localized that patients feel a foreign body is present. Some bacterial infections produce membranes or pseudomembranes covering the conjunctiva. Allergic conjunctivitis results from histamine release by mast cells, causing redness, conjunctival swelling, itching, and increased tearing. Diagnosis is often based on signs and symptoms, and a slit lamp examination can improve accuracy, with examination of the inner eyelid conjunctiva being more diagnostic than that of the scleral surface.
Reader's Guide
Conjunctivitis is a common condition that affects millions annually, with viral causes accounting for approximately 80% of adult cases and bacterial causes responsible for about 70% of childhood cases. While most cases resolve without specific treatment, antibiotics can shorten bacterial infections, and antihistamines or mast cell inhibitor drops are used for allergic cases. Prevention partly relies on handwashing. The condition typically resolves in one to two weeks, but further diagnosis and treatment may be required if visual loss, significant pain, sensitivity to light, or signs of herpes occur, or if symptoms do not improve after a week. Neonatal conjunctivitis may also require specific treatment.
Did You Know?
- Between three and six million people get acute conjunctivitis each year in the United States.
- Approximately 80% of conjunctivitis cases in adults are due to viruses, with 65% to 90% of those caused by adenoviruses.
- Allergic conjunctivitis affects 15% to 40% of the population.
- Bacterial conjunctivitis in children is responsible for about 70% of cases, commonly caused by Staphylococcus aureus, Streptococcus pneumoniae, and Haemophilus influenzae.
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