title: Sample size calculations for ophthalmologic studies.
abstract: Sample size calculations are shown for some common ophthalmologic study designs in which two treatments are to be compared. Included are the following three designs: 1, only one eye per subject; 2, both eyes, with each eye assigned to a different treatment; and 3, both eyes undergoing a common treatment. Continuous and binary outcomes are considered. The correlation between eyes is accounted for in the computations using a simple correction factor. For design 3, the formulas allow for a mixture of single-eye and double-eye eligible subjects. A computer program that performs the calculations is available.
authors.affiliation: Department of Preventive Medicine, University of Southern California School of Medicine, Los Angeles 90033.
authors.forename: W J
authors.initials: WJ
authors.lastname: Gauderman
authors.forename: W E
authors.initials: WE
authors.lastname: Barlow
mesh_terms: D006801:Humans; D009885:Ophthalmology / Q000379:methods*; D012107:Research Design; D012984:Software; D013223:Statistics as Topic; D015348:Vision, Binocular; D015349:Vision, Monocular