In vivo measurements of epidermal thickness with optical coherence tomography and confocal laser scanning microscopy: a comparison of methods

Abstract

Two noninvasive optical techniques, optical coherence tomography (OCT) and confocal laser scanning microscopy (CLSM) were used to measure the thickness of the epidermis of volunteers. It was found that due to their different resolution and penetration behavior, these two techniques are sensitive to different markers of the epidermal-dermal boundary. In CLSM, the tops of the dermal papillae are clearly and individually visible, whereas in OCT the fibrous structures immediately below the basal cell layer show up most clearly. Image segmentation algorithms were devised for automatic epidermal thickness determination. Both techniques were applied in a study into the effects of ultraviolet irradiation on the thickness of the epidermis. After exposure to a cumulative does of 15.7 (+/- 1.0) personal minimal erythema doses over three weeks, the changes were so small that only CLSM was able to discern them, due to its superior resolution. On average, it was found that the epidermis increases in thickness by 3 micrometers (p=0.011), which could be attributed entirely to a thickening of the stratum corneum.