After standardized training, 6 raters independently rated 21 patients with mild to severe melasma
once daily over a period of 2 days to determine intrarater and interrater reliability. Validation was
performed by comparing the MASI with the melasma severity scale. The darkness component of the MASI
was validated by comparing it with the difference between mexameter scores for affected versus adjacent
normal-appearing skin. The area component of the MASI was validated by comparing it with the area of
each section of the face determined by computer-based measurement software.