Table 6: Average difference between melasma and healthy skin.

Parameter Relative difference STD

Melanin 2.06 0.097
Epidermis thickness 1.12 0.016
Haemoglobin concentration 1.18 0.037
Oxygenated haemoglobin 0.92 0.012
Dermis thickness 1.09 0.041

STD: standard deviation.