No abstract

Lasers are used in the minimalistic or non-invasive diagnosis and treatment of skin disorders.Less laser light reaches the deeper skin layers in dark skin types, due to its higher epidermal melanin concentration compared to lighter skin. Laser-tissue interaction modelling software can correct for this by adapting the dose applied to the skin. This necessitates an easy and reliable method to determine the skin's type. Non-invasive measurement of the skin's melanin content is the best method. However, access to samples of all skin types is often limited and skin-like phantoms are used instead. This study's objective is to compare experimentally measured absorption features of liquid skin-like phantoms representing Skin Types I to VI with a realistic skin computational model component of ASAP®. Sample UV-VIS transmittance spectra were measured from 370 to 900 nm and compared to simulated results from ASAP® using the same optical parameters. Results indicated non-monotonic absorption features towards shorter wavelengths, which may allow for more accurate ways of determining melanin concentration and expected absorption through the epidermal layer. This suggests possible use in representing optical characteristics of real skin. However, a more comprehensive model and phantoms are necessary to account for the effects of sun exposure.4

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 2 cutaneous melanin and erythema, but this is complex and has been mostly used for light-tomedium pigmented skin. Handheld reflectance spectrophotometers, such as the Mexameter® 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. 503 participants comprised 68.5% self-identified Black African, 9.9% Indian/Asian, 18.4% White and 2.9% Coloured. The majority of Black African (45%), Indian/Asian (34%) and Coloured 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 colour in Black skin given sun-related health risks in vulnerable groups in Africa.

No abstract