Elucidating the contribution of Rayleigh scattering to the bluish appearance of veins

Abstract

The bluish appearance of veins located immediately beneath the skin has long been a topic of interest for biomedical optics researchers. Despite this interest, a thorough identification of the specific optical processes responsible for this phenomenon remains to be achieved. We employ controlled in silico experiments to address this enduring open problem. Our experiments, which are supported by measured data available in the scientific literature, are performed using first-principles models of light interaction with human skin and blood. Using this investigation approach, we quantitatively demonstrate that Rayleigh scattering caused by collagen fibrils present in the papillary dermis, a sublayer of the skin, can play a pivotal role in the bluish appearance of veins as suggested by previous works in this area. Moreover, also taking color perception aspects into account, we systematically assess the effects of variations in fibril radius and papillary dermis thickness on the coloration of veins under different illuminants. Notably, this assessment indicates that Rayleigh scattering elicited by reticulin fibrils, another type of fibril found in the papillary dermis, is unlikely to significantly contribute to the bluish appearance of veins. By strengthening the current understanding of light attenuation mechanisms affecting the appearance of skin and blood, our investigation contributes to the development of more effective technologies aimed at the noninvasive measurement of the physiological properties of these tissues.

Intense pulsed light for the treatment of pigmented and vascular disorders and lesions: A review

“…In this type of scattering, structures such as chromophores smaller in magnitude than the wavelength of the light being emitted have a more prominent scattering effect at the blue end of the visible spectrum. 53,54 Scattering leads to less absorption by targeted chromophores and less light penetration to deeper layers of the skin. This explains why red light is able to penetrate 4-5 mm below the skin, while blue light is only able to penetrate 1 mm below the skin.…”

“…It has been suggested that Rayleigh scattering accounts for the blue coloration of veins. In this type of scattering, structures such as chromophores smaller in magnitude than the wavelength of the light being emitted have a more prominent scattering effect at the blue end of the visible spectrum 53,54 . Scattering leads to less absorption by targeted chromophores and less light penetration to deeper layers of the skin.…”

Fast and precise image generation of blood vessels embedded in skin

“…Leeuwen et al postulated that the Rayleigh scattering of skin has a major influence on the typical bluish color of veins. 3 By comparing Figs. 9(c) and 9(d), one can clearly see that even a λ −1.5 dependency of μ 0 s ðλÞ leads to a bluish appearance of the vessel.…”

“…Recently, it was postulated that Rayleigh scattering in the skin has a major impact on the bluish appearance of blood vessels. 3 Studies of other authors focused on related topics, for example, the multiple influences on the color appearance of skin, such as melanin concentration as well as different melanin types, the oiliness of skin or the blood concentration in skin. 4,5 Besides the interests to render skin correctly, diagnostics methods, such as the evaluation of erythema for different skin types, efficient port wine stain treatment, or forensic applications, where the colors of bruises are studied, also benefit from the understanding of light propagation in human skin.…”

Appearance Modelling of Living Human Tissues

“…More specifically, both models compute the corresponding Rayleigh scattering coefficient as a function of the fibril's radius and then adjust the direction of light propagating in this tissue accordingly. These features proved to be essential for the identification of the biophysical mechanisms responsible for the bluish appearance of cyanotic skin [BVC17] and subcutaneous veins [SRVL18].…”