Visible light. Part I: Properties and cutaneous effects of visible light

Approximately fifty percent of sunlight reaching the Earth’s surface is visible light (400–700 nm). Other sources of visible light include lasers, light-emitting diodes (LEDs), and flash lamps. Photons from visible light are absorbed by photoreceptive chromophores (e.g., melanin, heme, and opsins), altering skin function by activating and imparting energy to chromophores. Additionally, visible light can penetrate the full thickness of the skin and induce pigmentation and erythema. Clinically, lasers and light devices are used to treat skin conditions by utilizing specific wavelengths and treatment parameters. Red and blue light from LEDs and intense pulsed light (IPL) have been studied as anti-microbial and anti-inflammatory treatments for acne. Pulsed dye lasers are used to treat vascular lesions in adults and infants. Further research is necessary to determine the functional significance of visible light on skin health and wellness without confounding the influence of ultraviolet and infrared wavelengths.