The estimate of approximately 320 to 350 screenings to find approximately 80 RPS positive subjects was based on previous studies documenting approximately 25% prevalence of adenoviral conjunctivitis among patients with acute conjunctivitis. The estimated mean time to viral eradication of 7.0 days for the placebo was based on a placebo arm of a previous study evaluating the safety and efficacy of cidofovir in the treatment of viral epidemic keratoconjunctivitis and the estimated mean time to viral eradication of 5.5 days was based on assumed clinically significant decrease of 1.5 days compared to the placebo arm.