The primary evaluation variable is the proportion of present or new cases of endocrine ophthalmopathy. The null-hypothesis is that there is no differences between the two treatment alternatives according to this proportion (H0:pi 1 = pi 2). The number of patients in each group when performing a two-side significance test on the 5% level for different demands on power and different values in the given proportions of the hypothesis is shown in a separate diagram. With 72 patients in each group there is 80 % chance (power) to get significant results if the real difference is 0.2. The hypothesis is tested with Mantel Haenzels test and further analyses performed with logistic regression which take into consideration the effect of prognostic factors.