Measurement of cutaneous erythema by means of photodensitometry: application to cutaneous photosensitivity

Abstract

We have developed a photodensitometry method to evaluate the intensity of cutaneous erythema objectively. The method measures the optical density of photographic slides of cutaneous erythema. It combines techniques used commonly but separately by investigators: diffuse transmittance spectroscopy (which is a variant of diffuse reflectance spectroscopy) and photography. We have used this method to study photosensitivity in 22 volunteers who received increasing doses of ultraviolet radiation to the back. Our work confirms the usefulness of an important parameter in photobiology: the regression slope of the curve representing the erythema index, a function of the logarithm of the dose applied.

Phototesting based on a divergent beam – a study on normal subjects

“…Over recent years, non-invasive, skin physiological techniques have increased the possibility of objectively measuring erythema, including the erythemal response to UVB. Reflectance spectrophotometry, polarized light photography, colorimetry, spectroradiometry, photoplethysmography and photodensitometry (10)(11)(12) are some of the techniques that make it possible to quantify UV-induced erythema and construct dose-response curves. Laser Doppler flowmetry (LDF) and Laser Doppler Perfusion Imaging (LDPI) have been used in this context and have shown themselves to be valuable tools (9,(13)(14)(15).…”