Sample size
diabetic, CMT
To have a power of 90% to detect a 30 μm difference of CMT in 12 weeks, we needed 50 subjects in each group. It was based on the assumed standard deviation of 0.26 which was obtained in the pilot phase of this study. The probable attrition of up to 30% and type one error of 0.05 were also considered. Fifty-eight diabetic patients having the eligibility criteria were enrolled in each group due to overcome the possible loss of follow-up.