[Standard designs of epidemiological studies and their characteristics in ophthalmology]

This text gives an overview on standard epidemiological study designs and their main advantages and limitations concerning clinical and economical aspects, of performance. Ophthalmological examples are used to illustrate the design characteristics of cross-sectional, cohort and case control studies. These designs are compared by the fictitious planning of an epidemiological study to assess the prophylactical relevance of intraocular antibiotics against post-cataract endophthalmitis; general practical hints for the designing of epidemiological studies are given.