For detecting and statistically securing correlations between the iris of a test subject and his state of health, a data bank with images of the iris of M test subjects is established by means of the following method steps: obtaining an image of the iris (iris chart) of the M test subjects by opto-electronically scanning-in the pixels with defined color values in a predeterminable grid, conversion and storage of the M scanned-in iris charts in M data sets, each with a.times.b data fields of a value corresponding to the color value of the associated pixel, standardization of the M data sets in such a way that a standard value, which can be predetermined by a rule for computing, is formed for each data field and represents the normal color value of the associated pixel, forming a standard data set (DQ) from the mean values standardized in this way, which constitutes an iris chart with the statistical normal state of the iris of the M test subjects, and storing the standard data set (DQ) in a first section of a data carrier. Standardization permits a statistically unequivocal association (if present) between specific illnesses and corresponding deviations of the iris image from a normal state. This can be used for a computer-controlled iris diagnosis.