Light TCA peels for skin rejuvenation: Effects on skin hydration, skin barrier function and skin elasticity

Abstract

With the aging of the American population, particularly those 76 million individuals known as the “baby boomers” starting to turn 50, a great deal of attention has been focused on “anti-aging” therapies, not only for general health purposes, but also for cutaneous aging. The aging process on the skin results in medical as well as cosmetic consequences.These aging effects of the skin are generally characterized as resulting from both an intrinsic process as well as an extrinsic process. Intrinsic aging refers to those processes that result purely from the passage of time. These effects generally start to become visible around age 30 to 35 and generally are subtle until more advanced years (generally over age 60) and are most easily visualized in non–sun-exposed areas of the skin. These effects include thinning of the epidermis, hypocellularity of the dermis, and a gradual decrease in numbers of dermal blood vessels, collagen, and elastic tissue. This results in pallor and fine wrinkles, with loss of elasticity and sagging of the skin.19Extrinsic aging is due primarily to the effects of environmental ultraviolet (UV) radiation. There are overwhelming epidemiologic and laboratory data to indicate that sun exposure is the single most important factor in causing extrinsic aging of the skin, hence, the terms photoaging and photodamage. For the average person, the vast majority of this sun exposure occurs during multiple brief exposures to the sun during daily normal activities, not in the pursuit of a tan.This chronic cumulative UV exposure results in the development of actinic keratoses, squamous cell carcinoma, basal cell carcinoma, and melanoma. UV light is considered a “complete carcinogen”: It not only initiates cancers through DNA mutations but also promotes their growth through the inflammatory processes associated with cumulative UV exposure.47 This has resulted in the annual appearance of greater than one million new cases of basal cell carcinoma and squamous cell carcinoma, as well as over 38,000 new cases of melanoma annually in the US population.21, 37 The additional effect of ozone depletion in the atmosphere has led to the conclusion that these skin cancers will become even more common. The United States Environmental Protection Agency estimates that 12 million additional cases of skin cancer and 210,000 additional skin cancer deaths will occur in the next 50 years from the currently existing amount of ozone depletion.13, 37 Should it worsen beyond the current levels, these additional numbers will escalate as well. The cost of treating these medically significant precancers and cancers is enormous and increasing, both as the population age increases and the ozone layer decreases, currently costing billions of dollars annually. One study of people over 50 years of age found that 100% had evidence of photodamage and 65% had significant damage, including actinic keratoses and skin cancers.3 Early recognition and effective treatment of photoaged or photodamaged skin will decrease the numbers of these lesions as well as the cost of treating them.In addition to the medically significant changes, the basic fact that cumulative sun exposure increases with age has led to the association of various signs of sun damage with chronological aging. It is these changes that often motivate the patient to seek medical evaluation, because they may be unaware of the significance of the visible changes associated with actinic keratoses and various skin cancers per se, but rather view them all as a sign of “premature aging,” at any age.Photodamage accounts for more than 90% of the unwanted changes in skin appearance of the sun-exposed areas. These changes include fine to coarse wrinkling, laxity, leathery and coarse skin texture progressing to atrophy in severe photodamage, irregular pigmentation, dry scaling and roughness of the skin surface, telangiectasia, and sallowness, as well as easy bruisability.19, 39, 49Solar elastosis causes the deposition of an abnormal, yellow, amorphous elastotic material in the upper dermis that replaces normal collagen and elastin and does not have the resiliency or structure of normal elastic tissue. The walls of the reduced numbers of blood vessels become thin and fragile, resulting in clinical purpura from mild trauma. The compromised maturation of keratinocytes and abnormal melanization of the epidermis result in irregular pigmentation as well as precancerous and cancerous epidermal cells.Facial skin aging has been associated with negative views of body image, self-esteem, and self-confidence.24, 25, 40, 41 As a consequence of all of these medical, cosmetic, and psychological factors, reversal of photoaging has become a frequent goal pursued by the public, the medical profession, and the cosmetic industry.