Overview
Conjunctivitis is inflammation of the conjunctiva, the clear membrane covering the white of the eye and the inner eyelids. It causes redness, discharge, and discomfort. The most common forms are bacterial (sticky eye), viral (watery, highly contagious), and allergic. Most cases are self-limiting and resolve without specific treatment.
How common is it?
Conjunctivitis is one of the most common eye conditions, accounting for approximately 1 to 2% of all GP consultations. Viral conjunctivitis is most prevalent in winter; allergic in spring and summer. Bacterial conjunctivitis is more common in children.
Causes and risk factors
Infective conjunctivitis is caused by bacteria or viruses spread by direct contact with secretions. Allergic conjunctivitis is triggered by allergens.
Common risk factors
- Viral: adenovirus (most common), herpes simplex virus, enterovirus — spreads readily by hand contact
- Bacterial: Staphylococcus aureus, Streptococcus pneumoniae, Haemophilus influenzae; in neonates and young adults: Neisseria gonorrhoeae, Chlamydia trachomatis
- Allergic: seasonal (pollen) or perennial (dust mite, animal dander)
- Chemical or irritant: chlorine, contact lens solutions, cosmetics
- Dry eyes or blepharitis
Symptoms
- Redness of the white of the eye
- Discharge: purulent and sticky (bacterial), watery (viral), mucoid and ropy (allergic)
- Crusting of eyelids, especially on waking
- Itching (predominant in allergic conjunctivitis)
- Gritty or burning sensation
- Photophobia in severe cases or if cornea is involved
- Preauricular lymph node enlargement in viral conjunctivitis
When to see a doctor
See a doctor urgently for vision change, severe pain, photophobia, copious purulent discharge in a newborn (gonococcal — an emergency), or contact lens-associated red eye. These may indicate more serious conditions.
Diagnosis
Clinical diagnosis. Conjunctival swabs for neonates (gonococcal and chlamydial), and for persistent or severe cases. Skin prick testing or specific IgE for allergic conjunctivitis if needed.
Treatments
Watchful waiting (viral and mild bacterial)
Most cases of infective conjunctivitis resolve spontaneously within 1 to 2 weeks. Regular cleaning of eyelids with cooled boiled water on a clean cotton pad, and not sharing towels.
Antibiotic eye drops
Chloramphenicol eye drops (available OTC) or fucidic acid gel for bacterial conjunctivitis. Shorten duration by 1 to 2 days. Indicated if symptoms are severe or persistent, or in the immunocompromised.
Allergic conjunctivitis treatment
Antihistamine eye drops (olopatadine, ketotifen) or sodium cromoglicate for mild cases. Oral antihistamines if systemic allergic symptoms coexist. Cold compresses reduce discomfort.
Self-care and lifestyle
- Wash hands frequently and thoroughly, especially after touching the eyes
- Do not share towels, pillowcases, or eye cosmetics
- Remove contact lenses and do not wear until infection resolves
- Cold compresses to reduce swelling and discomfort
Prevention
Hand hygiene is the most effective prevention for infectious conjunctivitis. Minimising allergen exposure reduces allergic conjunctivitis frequency.