Diffuse Reflectance Spectroscopy Versus Mexameter super( registered ) MX18 Measurements of Melanin and Erythema in an African Population

Melanin provides protection against excess exposure to solar ultraviolet radiation (UVR) and related adverse health effects. Diffuse reflectance spectroscopy (DRS) can be used to calculate cutaneous melanin and erythema, but this is complex and has been mostly used for light-to-medium pigmented skin. Handheld reflectance spectrophotometers, such as the Mexameter super( registered ) MX18, can also be used. We compared DRS-calculated melanin and erythema values with Mexameter melanin and erythema index values to understand how these techniques/measurements correlate in an African population of predominantly deeply pigmented skin. Five hundred and three participants comprised 68.5% self-identified Black African, 9.9% Indian/Asian, 18.4% White and 2.9% Colored. The majority of Black African (45%), Indian/Asian (34%) and Colored (53%) participants self-identified their skin as being "brown." Measured melanin levels increased with darker self-reported skin color. DRS-calculated and Mexameter melanin values demonstrated a positive correlation (Spearman rho = 0.87, P < 0.001). The results from both instruments showed erythema values were strongly correlated with their own melanin values. This finding is considered spurious and may result from the complexity of separating brown and red pigment when using narrowband reflectance techniques. Further work is needed to understand melanin, erythema and color in Black skin given sun-related health risks in vulnerable groups in Africa. Melanin provides protection against excess sun exposure. Diffuse Reflectance Spectroscopy (DRS) is used to calculate melanin and erythema, but has mostly been used for light-to-medium pigmented skin. We compared DRS-calculated melanin and erythema values with a handheld reflectance Mexameter melanin and erythema values to understand how these techniques/measurements correlate among Africans with predominantly deeply pigmented skin. DRS-calculated and Mexameter melanin values demonstrated a positive correlation. Both instruments' results showed that erythema values were strongly correlated with their own melanin values. Further work is needed to understand melanin, erythema and color in Black skin, given sun-related health risks posing vulnerable groups in Africa.