Infectious Conjunctivitis: Types, Treatment and Preventing Spread

Conjunctivitis — inflammation of the membrane covering the white of the eye and the inside of the eyelids — is one of the most common reasons people seek eye care. Most cases are viral and self-limiting, but distinguishing infectious from allergic, and viral from bacterial or chlamydial, determines both treatment and whether the patient needs to be isolated. Acute haemorrhagic conjunctivitis, epidemic keratoconjunctivitis and trachoma are the infectious types that drive outbreaks, and the Chinese expert consensus on clinical prevention and control sets out how they should be identified, managed and contained.

Telling them apart

Viral conjunctivitis is the commonest: watery discharge, gritty sensation, redness, often starting in one eye and spreading to the other within days, frequently with a recent cold or sore throat and with tender pre-auricular lymph nodes. Acute haemorrhagic conjunctivitis is a dramatic variant with subconjunctival bleeding and rapid onset, caused most often by enterovirus or coxsackievirus, and it spreads explosively. Epidemic keratoconjunctivitis, usually adenovirus, is more severe: intense redness, tearing, light sensitivity, a membranous surface, and — after a week or two — corneal infiltrates that can blur vision for weeks or months. Bacterial conjunctivitis produces thick yellow-green discharge that crusts the lids shut, especially on waking, usually in one eye. Chlamydial (trachoma or inclusion conjunctivitis) is chronic, with follicles on the inner lid and, in trachoma, scarring that can eventually cause blindness after repeated infections. Allergic conjunctivitis itches intensely, is watery, and occurs in both eyes with a seasonal or exposure history — it is not infectious.

What treatment helps

Viral conjunctivitis is self-limiting over one to three weeks and has no specific antiviral for routine use: cold compresses, lubricants and strict hygiene are the treatment. Topical steroids are sometimes used for severe adenoviral keratitis under ophthalmological supervision, but inappropriate steroid use prolongs viral shedding and worsens corneal involvement — never use leftover steroid drops for a red eye. Bacterial conjunctivitis is usually mild and self-limiting, but topical antibiotics shorten the illness and reduce transmission; they are prescribed when discharge is significant or the case is severe. Chlamydial infection requires systemic antibiotic treatment — and, in trachoma-endemic settings, public health measures — because topical treatment alone does not eradicate it.

Infection control

This is where the consensus is most emphatic. Infectious conjunctivitis is highly contagious through hands, towels, shared eye drops, contaminated instruments and swimming water. Measures include: frequent handwashing; not sharing towels, pillows, cosmetics or eye drops; avoiding contact lenses during infection and discarding the current pair and case; staying away from work, school and swimming pools during the contagious period — typically until discharge resolves, and longer for adenoviral disease; and, in clinics, separating suspected cases, using single-use instruments or rigorous sterilisation, and disinfecting surfaces and tonometer tips between patients.

When to seek urgent care

A red eye with significant pain, marked light sensitivity, reduced vision, a cloudy or white cornea, a fixed irregular pupil, severe headache with nausea, or contact lens wear should be assessed urgently — these suggest keratitis, uveitis or acute glaucoma rather than simple conjunctivitis. Newborns with conjunctivitis need urgent assessment, because neonatal chlamydial or gonococcal infection can threaten sight.