Corneometrie

Corneometrie is a non-invasive analytical technique used to assess the hydration level of the stratum corneum, the outermost layer of the skin. It relies on a handheld device called a corneometer, which measures the skin’s dielectric properties, primarily capacitance. These properties correlate with the water content in the superficial epidermis, so higher capacitance indicates greater skin hydration. The measurement is typically expressed in arbitrary units on a scale that is commonly near 0 to 100.

Principle and methodology

The corneometer probes the dielectric constant of the skin surface. Because water has a high dielectric constant, changes in water content cause measurable changes in capacitance. For reliable results, the skin area is acclimatized to room conditions before measurement, the skin is clean and free of lotions, and the probe is applied with a standardized, light pressure to avoid compressing the stratum corneum. Multiple readings are usually taken and averaged. Environmental factors such as temperature and relative humidity can significantly influence results.

Applications

Corneometry is widely used in cosmetics research and dermatology to evaluate moisturizers, serums, and other topical formulations. It is employed in clinical trials to monitor skin dryness in conditions such as xerosis and dermatitis and to compare the efficacy of products intended to improve skin hydration. Because it provides a rapid, non-invasive measure of surface hydration, it is often used alongside other modalities like transepidermal water loss (TEWL) for a more comprehensive assessment of skin barrier function.

Limitations

Results are reported in relative, device-specific units rather than absolute water content, and readings are sensitive to environmental conditions and probe pressure. Depth of measurement is limited to the superficial stratum corneum, and proper standardization is required to compare results across sessions or investigators.

See also: transepidermal water loss, skin hydration, corneometer.

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