Depth Penetration of Light into Skin as a Function of Wavelength from 200 to 1000 nm

Abstract

An increase in the use of light‐based technology and medical devices has created a demand for informative and accessible data showing the depth that light penetrates into skin and how this varies with wavelength. These data would be particularly beneficial in many areas of medical research and would support the use and development of disease‐targeted light‐based therapies for specific skin diseases, based on increased understanding of wavelength‐dependency of cutaneous penetration effects. We have used Monte Carlo radiative transport (MCRT) to simulate light propagation through a multi‐layered skin model for the wavelength range of 200–1000 nm. We further adapted the simulation to compare the effect of direct and diffuse light sources, varying incident angles and stratum corneum thickness. The lateral spread of light in skin was also investigated. As anticipated, we found that the penetration depth of light into skin varies with wavelength in accordance with the optical properties of skin. Penetration depth of ultraviolet radiation was also increased when the stratum corneum was thinner. These observations enhance understanding of the wavelength‐dependency and characteristics of light penetration of skin, which has potential for clinical impact regarding optimizing light‐based diagnostic and therapeutic approaches for skin disease.

NRF2 in dermatological disorders: Pharmacological activation for protection against cutaneous photodamage and photodermatosis

“…The average thickness (forearm dorsal) of the skin layers is shown on the left which varies with age, sex, BMI, solar exposure, and anatomical site [ 15 , 16 ]. The wavelength-dependent penetration depth into the skin is represented in %, by color scale, and size [ 11 , 12 ]. All illustrations were created with Bioredner program.…”

“…Both UVA and UVB radiation are capable of penetrating the human skin, albeit to different depths [ 11 , 12 ]. Penetration of UVR is wavelength- and location-dependent and may alter throughout the body, age, sex and BMI [ 12 ].…”

“…The higher energy, but low abundant UVB radiation, penetrates the stratum corneum and epidermis. Conversely, UVA reaches deeper into the dermal layer [ 11 ]. In general, approx.…”

“…Thus, only low UVB flux reaches the stratum basale in the epidermis, and only about 10% of the UVA radiation reaches the dermis ( Fig. 1 ) [ 11 ]. Hence, the skin provides a highly efficient barrier against UVR.…”

Progress on carbon dots and hydroxyapatite based biocompatible luminescent nanomaterials for cancer theranostics

“…Most of the conventional FL imaging probes operate in the ultraviolet-visible (UV–vis) range, a short wavelength region where most biological tissues absorb and scatter light resulting in tissue autofluorescence, low tissue penetration, and a low signal-to-background ratio [11] . The degree of scattering in the bio tissue is inversely proportional to the wavelength of light.…”