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A Deeper Look at Sun Damage

By: Jennifer Wild, DO
Posted: February 28, 2011, from the March 2011 issue of Skin Inc. magazine.

The one aspect of the esthetic industry that will never change is the fact that everyone’s skin ages. There will always be a need for the correction of the visible signs of aging and, although there are now numerous treatment options available, the first step in treating any skin concern is determining what is happening within the dermis and epidermis that is causing the symptoms. It is well known that ultraviolet (UV) rays from the sun are the No. 1 cause of visible aging, hence the popular term “sun damage.” By identifying the breakdown that occurs when the skin is exposed to the sun’s damaging rays and which ingredients can be used to limit or repair this breakdown, more deliberate treatment and product choices can be made.

Understanding sun-driven changes

External factors, such as sunlight, are responsible for many of the visible changes that take place in the skin. Although some minor alterations would occur regardless of a client’s amount of sun exposure, research indicates that up to 85% of visible aging is due to external factors.1 Client complaints regarding this damage are plentiful, and developing an understanding of how and when these changes take place will assist greatly in treatment. The following are among the most common presentations of cutaneous sun damage.

Deep wrinkling. This is not associated with the normal—or intrinsic—aging process; fine lines are normal, deep wrinkles are not. The sun’s UVA rays penetrate deeply into the dermis and cause the breakdown, disorganization and cross-linking of collagen. Cross-linking refers to what occurs when collagen fibers break down and fuse back together in a crisscross pattern. This process leads to reduced support and structure and, in the end, deep wrinkling. In addition, collagen and elastin breakdown is accelerated by an overproduction of matrix metalloproteinase (MMP) enzymes. Important MMP include collagenase and elastase, which break down collagen and elastin, respectively. Studies have found that MMP are increased within minutes of UV exposure, making any time spent outdoors potentially destructive to the skin.2

Coarsening. This refers to keratinization of the skin, or the abnormal buildup of keratinocytes. Coarsening is responsible for the dull, thickened and rough-textured appearance often seen in more mature clients. Many refer to coarsening as an orange peel or leatherlike appearance. UVA and UVB radiation can cause an overproduction of epidermal cells, and stratum corneum thickness can double as a result of repeated sun exposure. This obvious, rough-textured appearance only occurs in certain cases of sun damage.

Dehydration. This is common in nearly all cases of sun damage. Dehydration of the skin involves a lack of water moisture. Many incorrectly believe that sebum production decreases with age. In fact, the dryness that is common in clients with aging skin is due to a decrease in the skin’s natural moisturizing factor (NMF). A drop in NMF levels occurs naturally with age, but is worsened by environmental exposure. Even the smallest disruption in this hydrating group of substances can significantly decrease surface moisture levels, and slow the desquamation and cell turnover process. Additionally, hyaluronidase, which is another MMP responsible for the degradation of hyaluronic acid, increases in response to the inflammation caused by UV rays and free radical damage. Clients suffering from sun damage may experience a thickened, dry stratum corneum that appears flaky, dull and rough. This dryness can be exacerbated by improper cleansing and moisturization practices, or the regular use of inherently drying ingredients, such as alcohol or glycolic acid.