Viral Conjunctivitis

Viral conjunctivitis is the commonest infectious conjunctivitis, accounting for about 75 percent of acute conjunctivitis.

• Adenovirus (serotypes 3, 4, 7, 8, 19, 37) is the most frequent cause.
• Other viruses: herpes simplex virus, varicella zoster virus, enterovirus 70 and coxsackievirus A24 (acute haemorrhagic conjunctivitis), measles, rubella, mumps, Epstein-Barr virus, molluscum contagiosum, and SARS-CoV-2 (rare).
• Highly contagious; incubation 5 to 12 days, shedding up to 14 days.

• Watery discharge, redness, foreign body sensation, burning, usually bilateral with sequential involvement.
• Follicular reaction on the inferior tarsal conjunctiva, tender preauricular lymphadenopathy, lid swelling, sometimes subconjunctival haemorrhages and pseudomembranes.
• History of upper respiratory tract infection or sore throat, and a sick contact.
• Photophobia and blurred vision signal corneal involvement (subepithelial infiltrates at 1 to 2 weeks).
• Herpes simplex: unilateral, with vesicles, dendritic keratitis.
• Enteroviral: abrupt onset with massive subconjunctival haemorrhages, heals in 5 to 7 days.

• Clinical diagnosis; point-of-care adenoviral antigen test (rapid immunoassay) when available.
• PCR of conjunctival swab for adenovirus, herpes simplex, varicella zoster in atypical or severe cases.
• Fluorescein staining for epithelial keratitis, and slit lamp examination of the cornea.
• Pseudomembranes: examine by lid eversion. Check for HSV or VZV signs (vesicles, dermatomal rash).

• Self-limited over 1 to 3 weeks. Supportive: cold compresses, preservative free lubricants every 2 to 4 hours.
• Antibiotics are not indicated unless bacterial superinfection.
• Remove pseudomembranes under topical anaesthetic with a cotton bud or forceps and apply topical steroids (prednisolone acetate 1 percent or fluorometholone 0.1 percent three or four times daily, tapered over 2 to 3 weeks) for membranes or subepithelial infiltrates reducing vision. Steroids may prolong viral shedding and risk exacerbating herpes, so exclude herpetic disease first.
• Povidone iodine 0.6 percent with dexamethasone 0.1 percent drops have been used in severe adenoviral disease.
• Herpes simplex conjunctivitis or keratitis: aciclovir 3 percent ointment five times daily or ganciclovir 0.15 percent gel five times daily until healing, then three times daily for 7 days; or oral aciclovir 400 mg five times daily for 7 to 10 days.
• Infection control: hand washing, no sharing of towels, avoid school or work for 7 to 14 days while red and weeping, disinfect instruments and tonometer tips (sodium hypochlorite 0.5 percent for 10 minutes).