Obtaining accurate, repeatable assessments of dermal characteristics is the key to many studies into the efficacy and impact of ingested and topical drugs affecting pigmentation. Spectral reflectance measurements offer an objective way to measure skin throughout dermatological studies, providing quantitative data on color and absorbance of skin. Ocean Optics modular products offer the flexibility to design a measurement system for a wide variety of dermal studies, both at and beyond visible wavelengths, from the UV to the near infrared.
By way of demonstration, we simulated the development of models for melanin and moisture in skin. We began by identifying which spectra make up the total reflectance spectrum of skin, then developed very simple models to report a “Melanin Index” and “Moisture Index” using just a few wavelengths each.
Melanin versus Hemoglobin: Two Important Contributors
Melanin is a dark pigment found in skin, contributing to skin tone and responsible for protection from solar radiation and the visible tanning of skin upon exposure to UV light. Surprisingly little is known about melanin, despite its key role in skin pigmentation. Melanin is the name for a group of insoluble biopolymers with various structures that have proven difficult to isolate and study1. Melanin exhibits an unstructured absorbance in the visible portion of the spectrum that falls off exponentially with increasing wavelength. Despite its lack of structure, melanin could potentially be quantified spectroscopically using chemometric analysis.
Hemoglobin and deoxyhemoglobin are iron-containing metalloproteins responsible for oxygen transport in the body, and as such are found co-located with melanin in tissue. The visible spectrum of hemoglobin exhibits characteristic peaks at ~540 nm and ~580 nm, while deoxyhemoglobin peaks at ~560 nm. A pulse oximeter uses the difference in th