Objective determination of skin phototypes in healthy children by diffuse reflectance spectroscopy

The clinical method of evaluating the color of the skin based on visual assessment is subjective and thus inaccurate. The objective determination of skin phototypes and levels of melanin in the skin is important for diagnosing the pigment disorders and also for adequate photoprotection. Diffuse reflectance spectroscopy (DRS) is a non-invasive, precise and objective method for quantifying the melanin levels.

The aim of this study is to assess the characteristic DRS spectrum of healthy skin in children and to detect the differences between them based on age, gender and skin phototype.

Skin pigmentation was measured by DRS in 73 children patients with experimental spectrophotometer UM-ES600. The amount of melanin is quantified from the obtained DRS spectra by proposed melanin quantification angle α obtained by comparing the reflectance properties of skin sample and universal depigmented sample (albino skin).

We evaluated spectroscopic characteristics of children's healthy skin depending on age, gender and phototype. The value of melanin quantification angle α grew proportionally from phototype I to phototype IV, without any correlation to age or gender. We confirmed a clear association between clinical determination of Fitzpatrick's skin phototypes and objective data collected by DRS and related angle α.

Our proposed index quantifies the difference in melanin levels in healthy children skin and also for different skin phototypes. The proposed method and melanin quantification angle α can further be used for the objectification of the progress of pigmentary diseases or for monitoring the effect of their therapy (Tab. 5, Fig. 4, Ref. 29).