A Prospective Study of Melanin Index in Those With Fitzpatrick Skin Phototypes I-VI

The "gold standard" method of assessing skin pigmentation is spectrophotometry; however, even as early as 1961 the potential for confounding by dilatation of blood vessels was recognized. (Monash 1961) Manual compression was used to express the blood from the field being measured. The red reflectance captured by reflectance spectrophotometer introduced an uncontrollable variable when measuring the tanning /pigmentation response of skin tone/color. Room temperature induced increased or decreased blood flow through the skin, which altered the findings by spectrophotometer. Other potentially confounding variables that changed blood flow were: recent exercise, and the flushing/blushing for emotional reasons. Since these conditions were difficult to reliably control on the sun exposed extremities, spectrophotometry was not a practical method to assess change in melanin over time as an outcome measure for efficacy of sun protection.

Digital imaging with videodermatoscopy utilizing a portable device that is supported by a laptop computer, provides a high resolution digital image for analysis. (EasyScan) As described by Yamamoto et al (2008), applying the Image J freeware to quantify the pigmentation in the digital image holds promise as a practical objective method to reliably assess skin tones based on the melanin content in a non invasive manner. With standardization, the software and hardware may quantify the constitutive pigment in the sun protected skin as the melanin index.