Susan Taylor, MD, FAAD, provides an overview of sun-caused skin damage.
Susan Taylor, MD, FAAD: This is DermView, understanding damage from sunlight and advances in sun protection. I’m Dr Susan Taylor, the Brunette Johnson Endowed Professor of Dermatology of the Perelman School of Medicine at the University of Pennsylvania. Let’s begin.
To provide an overview of the damage to the skin by sunlight, we need to divide it into the types of sunlight that we receive here on Earth. First, there’s UV-B. UV-B skin damage causes sunburn and it can also lead to skin cancer. We know that DNA oxidation produces the generation of reactive oxygen species. This can also lead to photo ageing as well as hyperpigmentation, and we can’t forget about immune suppression. When we think of UV-A1 skin damage, we know that UV-A penetrates more deeply into the dermis and this leads to DNA damage, photo ageing, and immune suppression. We sort of lump UV-A and UVB- damage together. We think of first- and second-degree sunburn, wrinkles, uneven skin tone, freckles, lentigines and problems like a melasma, for example. Then, there are preskin cancers, actinic keratosis, squamous cell and basal cell carcinomas, and melanoma. When we think of UV-A1 and visible light, the damage that occurs is a little bit different and we think in particular, of visible light, with the blue light rays. UV-A1 and visible light produces reactive oxygen species, and it causes oxidative stress that can lead to redness or erythema of the skin that only lasts a couple of hours. But what really happens is that pigmentation or hyperpigmentation can occur, and that hyperpigmentation is long lasting. Hyperpigmentation from visible light is further exacerbated or aggravated by UVA1 and all of this can lead to photo ageing.
Free radicals can produce all kinds of damage to the skin. Free radicals that are produced by visible light can lead to temporary erythema or redness of the skin. More importantly, it can lead to long lasting hyperpigmentation of the skin. It can help cause disorders of pigmentation and exacerbate them as well. We find as clinicians that visible light prevents our medications from being as effective as they could be.
Transcript Edited for Clarity