Rationale:

• Superficial punctate keratitis is a common clinical feature of viral conjunctivitis (adenoviral more than picornaviral) and is associated with photophobia, foreign body sensation, and occasionally severe pain.
• Short incubation period (<24 h), rapid onset of symptoms (<5 h), and bilateral infection are common clinical features of picornavirus (enteroviral and coxsackievirus) infection, whereas incubation period and onset of symptoms is longer in adenoviral infection.
• Conjunctivitis caused by adenoviruses or picornaviruses is highly contagious.
• Muscle weakness may be associated with picornaviral conjunctivitis.
• Itching is more common in allergic conjunctivitis but may present in viral conjunctivitis.
• HSV may present without skin leasions in an identical way to adenovirus 4% to 5% of the time.

Evidence:

• Historical features associated with viral conjunctivitis are discussed in review articles (1; 2) and in book chapters about diseases of the outer eye (3; 4).
• A review of virologic and clinical studies of 478 patients with acute follicular conjunctivitis in Japan concluded that it is difficult clinically to differentiate HSV conjunctivitis from adenoviral conjunctivitis. There may be a biological difference between HSV strains causing keratitis and conjunctivitis (5).

Comments:

• A history of contact lens use or rheumatologic disease can suggest a more serious underlying pathology. Studies suggest that it is often difficult to differentiate viral from bacterial or allergic disease by the clinical exam. Clinical accuracy of about 40% to 70% compared to laboratory confirmation has been shown (6; 7; 8; 9).