Thirty eight viral positive culture subjects per treatment group yields 90% power to detect a statistically significant difference in time of viral eradication between ganciclovir gel 0.15% and placebo (hypromellose gel) assuming: (1) a mean time to viral eradication of 7.0 days in the placebo group and 5.5 days in the ganciclovir group, (2) an estimated standard deviation of 2.0 days for both groups, and (3) using a two-sided α = 0.05 (two sample comparison of means).