Improving the cosmetic appearance of photoaged skin with glycolic acid

Abstract

In part, the appearance of prematurely aged skin is caused by a thickened stratum comeum resulting from increased comeocyte cohesion. 1 Long-term UV radiation exposure also degrades collagen in the dermis, and excessive amounts of abnormal elastic fibers also tend to accumulate within the dermis of photodamaged skin. 2 Popular magazines have vigorously promoted the benefits of o~-hydroxy acids (AHAs) in reversing the adverse effects of the sun on the skin. Glycolic acid (GA) is a chemical exfoliant and was formerly employed in industry for metal cleaning and electroplating.* GA in low concentrations decreases corneocyte cohesion by promoting exfoliation of the outer layers of the stratum comeum. 3, 4 This is especially relevant because most pigmentation alterations associated with photodamage can be attributed to thickening of the stratum comeum. Although the outer stratum comeum is thinned by treatment with topical AHAs, Ditre et al.5 demonstrated a significant increase in overall epidermal thickness that appeared to be secondary to augmented synthesis of glycosaminoglycans and collagen. In addition, they also found significant reversal of basal cell atypia, dispersal of melanin pigmentation, and a return to a more normal rete pattern. These findings corroborate those of Van Scott and Yu, 6 who found that GA stimulated the synthesis of new collagen. Repeated and regular applications of GA to the face have been shown to diminish fine facial wrinkles significantly. 7 Physical exfoliation with a Loofah sponge or