Impact of Long-Wavelength UVA and Visible Light on Melanocompetent Skin

Abstract

The purpose of this study was to determine the effect of visible light on the immediate pigmentation and delayed tanning of melanocompetent skin; the results were compared with those induced by long-wavelength UVA (UVA1). Two electromagnetic radiation sources were used to irradiate the lower back of 20 volunteers with skin types IV-VI: UVA1 (340-400 nm) and visible light (400-700 nm). Pigmentation was assessed by visual examination, digital photography with a cross-polarized filter, and diffused reflectance spectroscopy at 7 time points over a 2-week period. Confocal microscopy and skin biopsies for histopathological examination using different stains were carried out. Irradiation was also carried out on skin type II. Results showed that although both UVA1 and visible light can induce pigmentation in skin types IV-VI, pigmentation induced by visible light was darker and more sustained. No pigmentation was observed in skin type II. The quality and quantity of pigment induced by visible light and UVA1 were different. These findings have potential implications on the management of photoaggravated pigmentary disorders, the proper use of sunscreens, and the treatment of depigmented lesions.

Melasma: A comprehensive update

“…A recent study revealed that visible light can produce significant pigmentation in normal skin, a finding that may be important in the pathogenesis of melasma. 3 With the currently available data, a broadspectrum UVA-and UVB-protective sunscreen with an SPF of at least 30 along with a physical block, such as titanium dioxide or zinc oxide, should be used by CAPSULE SUMMARY d Topical treatment of melasma includes hydroquinone, retinoids, chemical peels, and many other less well studied compounds. The evidence for improvement with laser therapy is mixed with a significant potential for worsening.…”

Phototherapy for sclerosing skin conditions

“…In addition, UVA1-induced pigmentation was dose dependent, leading the authors to suggest that intermittent low pulsed doses might be more effective than prolonged higher doses. Mahmoud et al demonstrated that UVA1 can induce pigmentation in patients with skin types IV-VI, but not with skin type II [34]. The results of studies to date investigating the effect of skin pigment on UVA1 efficacy present an interesting paradox in which clinical experience indicates efficacy across skin types but in vitro studies demonstrate abrogation of antisclerotic activity.…”

Challenges in photoprotection: Introduction

“…1 Furthermore, generation of cyclobutane-pyrimidine dimers has been shown to occur even after exposure to UVR has ended 2 ; this has been termed ''dark cyclobutane-pyrimidine dimer formation,'' and is associated with the presence of melanin, especially pheomelanin.…”