(See also Overview of Conjunctivitis.)
Conjunctivitis may accompany the common cold and other systemic viral infections (especially measles, but also chickenpox, rubella, and mumps). Localized viral conjunctivitis without systemic manifestations usually results from adenoviruses (up to 90% of viral conjunctivitis) and sometimes enteroviruses or herpes simplex virus (1.3 to 4.8% of viral conjunctivitis).
Epidemic keratoconjunctivitis usually results from adenovirus serotypes Ad 5, 8, 11, 13, 19, and 37 and tends to cause severe conjunctivitis. Adenoviruses can also be identified by genotypes. Genotype HAdV-D is associated with conjunctivitis and HAdV-D53 and HAdV-D54 have been associated with epidemic keratoconjunctivitis. Pharyngoconjunctival fever usually results from serotypes Ad 3, 4, and 7. Outbreaks of acute hemorrhagic conjunctivitis, a rare conjunctivitis associated with infection by enterovirus type 70, have occurred in Africa and Asia. Ebola virus and SARS-CoV-2 infections (which are associated with the highly contagious and potentially fatal Ebola hemorrhagic fever and COVID-19, respectively) can manifest with bilateral conjunctival hyperemia, tearing, and systemic symptoms. Caution and appropriate personal protective equipment should be used when examining patients with conjunctivitis, systemic symptoms, and travel from high-risk regions.
After an incubation period of about 5 to 12 days, conjunctival hyperemia, watery discharge, and ocular irritation usually begin in one eye and spread rapidly to the other. Follicles may be present on the palpebral conjunctiva. A preauricular lymph node is often enlarged and painful. Many patients have had contact with someone with conjunctivitis, a recent upper respiratory infection, or both.
In severe adenoviral conjunctivitis, patients may have photophobia and foreign body sensation due to corneal involvement. Chemosis may be present. Pseudomembranes of fibrin and inflammatory cells on the tarsal conjunctiva, focal corneal inflammation, or both may blur vision. Even after conjunctivitis has resolved, residual corneal subepithelial opacities (multiple, coin-shaped, 0.5 to 1.0 mm in diameter) may be visible with a slit lamp for up to 2 years. Corneal opacities occasionally result in decreased vision and significant halos and starbursts.
Diagnosis of conjunctivitis and differentiation between bacterial, viral, and noninfectious conjunctivitis (see table Differentiating Features in Acute Conjunctivitis) are usually clinical; special tissue cultures are necessary for growth of the virus but are rarely indicated. Nucleic acid amplification tests (NAAT) and other rapid, office-based immunodiagnostic tests, can be useful especially when the inflammation is severe and other diagnoses (eg, orbital cellulitis) must be ruled out. Features that may help differentiate between viral and bacterial conjunctivitis can include purulence of ocular discharge, presence of preauricular lymphadenopathy, and, in epidemic keratoconjunctivitis, chemosis. Patients with photophobia are stained with fluorescein and examined with a slit lamp. Epidemic keratoconjunctivitis may cause punctate corneal staining. Secondary bacterial infection of viral conjunctivitis is very rare. However, if any signs suggest bacterial conjunctivitis (eg, purulent discharge), cultures or other studies may be useful.
Differentiating Features in Acute Conjunctivitis
Viral conjunctivitis is highly contagious, and transmission precautions must be followed.
To avoid transmitting infection, physicians must
Patients should do the following:
Eyes should be kept free of discharge and should not be patched. Small children with conjunctivitis should be kept home from school to avoid spreading the infection.
Viral conjunctivitis is self-limiting, lasting 1 week in mild cases to up to 3 weeks in severe cases. It requires only cool compresses for symptomatic relief. However, patients who have severe photophobia or whose vision is affected may benefit from topical corticosteroids (eg, 1% prednisolone acetate 4 times a day). Corticosteroids, if prescribed, are usually prescribed by an ophthalmologist. Herpes simplex keratitis must be ruled out first (by fluorescein staining and slit-lamp examination) because corticosteroids can exacerbate it. Topical cyclosporin A eye drops are overall less effective but are helpful if corticosteroid drop use is limited by adverse effects.
Most viral conjunctivitis is a highly contagious infection caused by adenoviruses or enteroviruses.
Features that may help differentiate between viral and bacterial conjunctivitis can include purulence of ocular discharge, presence of preauricular lymphadenopathy, and, in epidemic keratoconjunctivitis, chemosis.
Diagnosis is usually clinical.
Treatment is usually cool compresses and measures to prevent spread.