Skin erythema assessment techniques.

Skin erythema may present owing to many causes. One of the common causes is prolonged exposure to sunrays. Other than sun exposure, skin erythema is an accompanying sign of dermatologic diseases, such as psoriasis and acne. Quantifying skin erythema in patients enables the dermatologist to assess the patient's skin health. Quantitative assessment of skin erythema has been the focus of several studies. The clinical standard for erythema evaluation is visual assessment; however, this standard has some deficiencies. For instance, visual assessment is subjective and ineffectual for precise color information exchange. To overcome these limitations, in the past three decades various methodologies have been developed in an attempt to achieve objective erythema assessments, such as diffuse reflectance spectroscopy and both optical and nonoptical systems. This review considers the studies published during the past three decades and discusses the performance, the mathematical tactics for computation, and the limited capabilities of erythema assessment techniques for cutaneous diseases. The achievements and limitations of the current techniques in erythema assessment are presented. The advantages and development trends of optical and nonoptical methods are presented to make the reader aware of the present technological advances and their potential for dermatological disease research.