Visible-light optical coherence tomography platform for the development of novel atopic dermatitis treatment

Atopic dermatitis is a chronic, relapsing inflammatory skin disease, which has one of the highest prevalence rates in the world. It is widely believed to be driven by deficiencies in the skin barrier layer, which is provided by the stratum corneum. The stratum corneum thickness determines the absorption rate of topical treatments and may correlate with its barrier function of preventing allergen penetration. Here we demonstrate a free-space, portable Fourier domain visible-light optical coherence tomography (OCT) system to study the stratum corneum thickness (5-15 mu m typically) in non-palmar human skin. We use a supercontinuum laser source, optimized for emission in the 500-700 nm range and achieve axial resolution of similar to 1 mu m in tissue (for the refractive index n = 1.55 of the stratum corneum). Our system has similar to -85 dB sensitivity at an A-scan rate of 125 kHz and about 1 mW of optical power onto the skin. High-quality B-scans from various human skin sites are obtained, with a clearly resolved stratum corneum layer presenting as a hypoechogenic dark layer, similar to that found in palmar skin with traditional OCT systems.