Evaluation d’une nouvelle technologie colorimétrique pour la distinction et la mesure de la pigmentation et de l’érythème cutanés

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Evaluation d’une nouvelle technologie colorimétrique pour la distinction et la mesure de la pigmentation et de l’érythème cutanés

Evaluation of a novel colorimetric technology for discrimination and measurement of cutaneous pigmentation and erythema

Baquié Mathurin¹, Kasraee Behrooz²

^{1 Geneva, Switzerland}

^{2 Scientis Pharma SA, Geneva, Switzerland}

Quantification of skin pigmentation by colorimeters is currently feasible. However, reproducibility and specificity of present devices is still limited. As a major inconvenience, alterations in skin erythema can bias melanin values measured by such devices.
In this study, Dermacatch® (Colorix, Switzerland), a new colorimeter with a novel technology for image capture and analysis (covering the entire visible light spectrum) has been compared with Mexameter® (Courage-Khazaka, Germany), the established narrow-band reflectance spectrophotometer.
Extended analysis with color charts showed better reproducibility of results with Dermacatch®. With the latter, melanin and erythema indexes increased proportionally and linearly to the darkening and reddening of each tested color type respectively; while Mexameter showed some linearity only for limited wavelenghts.

In vivo, skin pigmentation and erythema were artificially modulated on 12 volunteers. Six squares (4cm² each) on the lower back were exposed to increasing UVB doses of 450, 600 and 750 nm. Measurements (repeated 10 times) performed on days +2, +7 and +14 with both colorimeters indicated that…
… Dermacatch® was more sensitive, with more reproducible values for both pigmentation and erythema. The melanin values corresponding to increasing UVB doses were proportionally less linear with Mexameter®.
To analyze the potential bias of erythema on melanin values, the lower back treated or not with UVB was exposed to the vasodilator methylnicotinate and the vasoconstrictor clobetasol propionate. Measurements before and after treatments showed that…
…Dermacatch could much more specifically discriminate pigmentation from erythema.