We want to thank you for the time you took to read the article “Prevention of Corticosteroid-Induced Intraocular Pressure Elevation Using ISV-205”1 and to respond with questions. We also want to thank you for your kind words about the article.
Because of the lack of previous information regarding standard deviations or differences in intraocular pressure between treated and nontreated patients in large groups of steroid responders, we could not determine an accurate sample size for this study. Consequently, we determined the required sample size by using a statistical formula by Jacob Cohen.2 This formula is designed to estimate sample sizes when historical standard deviations, and differences, between treatment and nontreatment groups are not available.
Stewart WC. Preventing Steroid-Induced Glaucoma—Reply. Arch Ophthalmol. 2005;123(7):1018. doi:10.1001/archopht.123.7.1018-b