Background Adenoviruses are the most common cause of ocular viral infection worldwide. Conjunctivitis and keratoconjunctivitis caused by adenoviruses are highly contagious. Adenovirus is a non-enveloped, double-stranded DNA virus comprised of 53 serotypes. Unlike many enveloped viruses which can be more easily inactivated, adenoviruses are resilient to disinfection and are long lasting on fomites. The ocular infection generally begins unilaterally and, in many cases, spreads to both eyes. It may cause epidemics and endemics, being most commonly spread in the summer or winter. Epidemics are common in day care centers, schools and the military and have been spread in the offices of eye care professionals. Patients may have painful conjunctival membranes and palpable preauricular adenopathy. Subsequent subepithelial corneal infiltrates can cause light sensitivity, reduced vision and lead to irregular astigmatism. The differential diagnosis includes herpes simplex, Chlamydia and enteroviral infection.