Practical applications of cutaneous colorimetry.

Dermatologists have long tried to quantify skin color and had few results until the advent of tristimulus colorimetry. With the Minolta colorimeter, quantification of skin color has become a simple matter: skin color can be measured rapidly, noninvasively, and reproducibly. The instrument, which can be used by paramedical staff, provides data that lend themselves for comparison, irrespective of where they are collected. The instrument has enabled definition of the range of physiologic values of skin color, and has revealed marked variations between exposed and nonexposed skin. Constitutional skin color characterizes an individual's phenotype better than facultative skin color and is highly indicative of vulnerability to sunlight. It is therefore a parameter for predicting the immediate and delayed response to light stimulation. On the practical level, colorimetric skin color values can be used to study pigmentation capacity, to program photochemotherapy, and to predict the risk of, and prevent, actinic cancer. Colorimetry can be used to quantify the intensity of erythema of spontaneous and experimental lesions. It has been used to monitor the efficacy of anti-inflammatory treatment of psoriasis and atopic dermatitis. It has also been used in the study of reactions induced by physical and allergic stimuli. Finally, colorimetry is useful in cosmetology for choosing appropriate sunscreens, for studying the effect of depigmentation products, and for determining the delicacy of detergents, and in any other situation that requires the measurement of parameters correlated with skin color that cannot be appreciated by visual observation.