Conjunctivitis (Pink Eye): A Clinical Overview

Conjunctivitis, or pink eye, can be caused by viruses, bacteria, allergens, contact lens use, chemicals, fungi and certain diseases. This overview for health care providers covers the three most common kinds.

Causes

Viral. Causes include adenoviruses (one of the most common), rubella virus, rubeola (measles) virus, herpesviruses including herpes simplex virus, varicella-zoster virus (which also causes chickenpox and shingles), Epstein-Barr virus (which also causes infectious mononucleosis), and picornaviruses such as coxsackievirus A24 and enterovirus 70, which has caused outbreaks in other countries.

Bacterial. Many species can cause it, including Haemophilus influenzae, Streptococcus pneumoniae, Moraxella catarrhalis, Chlamydia trachomatis, Staphylococcus aureus, Moraxella lacunata, Neisseria gonorrhoeae and Neisseria meningitidis.

Allergic. This is the body's reaction to substances such as pollen from trees, plants, grasses and weeds; dust mites; animal dander; molds; contact lenses and lens solution; and cosmetics. It is common in people with other allergic conditions such as hay fever, asthma and eczema.

How it spreads

Signs and associated conditions

Depending on the virus, viral conjunctivitis can come with:

• respiratory infections such as a cold or flu
• pharyngoconjunctival fever: conjunctivitis with fever and sore throat, most often from adenovirus serotypes 3, 4 and 7
• epidemic keratoconjunctivitis (EKC): a more severe form, commonly from adenovirus serotypes 8, 19 and 37. It inflames the conjunctiva and cornea, can cause vision loss, spreads by direct contact, and has been linked to equipment used in eye exams
• acute hemorrhagic conjunctivitis: often associated with large epidemics worldwide, especially in tropical and subtropical regions, most commonly from enterovirus 70, coxsackievirus A24 and adenoviruses
• herpetic keratoconjunctivitis: linked to herpes simplex virus and blister-like skin lesions, and may affect only one eye
• rubella and measles: conjunctivitis can accompany these rash illnesses, usually with rash, fever and cough

Bacterial conjunctivitis overlaps in its signs with viral and allergic conjunctivitis, which can make it hard to diagnose. Typical signs are a red eye; pus-filled discharge that mats the eyelids together; chemosis; decreased vision; and eyelid swelling and pain.

Treatment

Most acute infectious conjunctivitis in adults is viral and clears on its own, without antimicrobials. Antiviral medicine may be used for more serious forms, such as those caused by herpes simplex or varicella-zoster virus.

Contact lens wearers with bacterial conjunctivitis are at higher risk of bacterial keratitis. They should remove their lenses, be treated with topical antibiotics and see an ophthalmologist promptly.

Counseling patients

• Advise patients with viral or bacterial conjunctivitis and signs of illness throughout the body to stay home, especially if they cannot avoid close contact with others. Students who cannot avoid close contact should not attend school.
• Patients can return to work or school with a clinician's approval, once any needed treatment has started.
• Patients with viral conjunctivitis should wash their hands often, use their own towels and avoid close contact with others.

Sources

• Centers for Disease Control and Prevention, "Clinical Overview of Pink Eye (Conjunctivitis)." https://www.cdc.gov/conjunctivitis/hcp/clinical-overview/index.html
• CDC, "Types of Bacterial Conjunctivitis": https://www.cdc.gov/conjunctivitis/hcp/clinical-overview/bacterial-types.html; "Preventing Epidemic Keratoconjunctivitis": https://www.cdc.gov/conjunctivitis/hcp/infection-control-ekc/index.html
• The source's "Neisseria gonorrhea," "Neisseria meningitides" and "Pharyngoconjunctivial" are corrected here to Neisseria gonorrhoeae, Neisseria meningitidis and pharyngoconjunctival.