Tretinoin 1% has also been used as a chemical peeling agent [22,23]. The efficacy of tretinoin peels was compared with glycolic acid peels in the treatment of melasma in dark skinned patients . In a split face study of ten Indian women, 1% tretinoin was applied to one half of the face, while 70% glycolic acid was applied to the opposite side. Peels were performed weekly. Significant improvement occurred on both sides as assessed by photographs and a Modi-
fied Melasma Area and Severity Index Score. However, there were no significant differences between the tretinoin peeled side and the gly-colic acid treated areas. Side effects despite the weekly frequency of peel applications were minimal throughout the 12-week study.
TCA peels were first described by Roberts in 1926. Many consider TCA the gold standard by which other peels are measured. Concentrations of 10-30% are used for superficial peeling. TCA precipitates epidermal proteins, causing sloughing and necrosis of the treated area. The extent of damage is concentration dependent. In contrast to glycolic acid, Jessner's solu tion, and salicylic acid, there is a substantially smaller window of safety when TCA peels are applied to skin types IV-VI. The frequency of post-peel hyperpigmentation is significantly more common in dark skin. Therefore, the author only uses TCA peels in patients recalcitrant to glycolic acid, salicylic acid, or Jessner's peels (Fig. 13.5a, b). TCA peels are cautiously used in darker-skinned patients. Indications include wrinkles, photodamage, stubborn pigmentation, and scarring.
In a histometric, immunohistochemical and ultrastructural study, TCA peeling in concentrations of 10, 20 and 30% were compared with dermabrasion in nine dark-skinned patients (Fitzpatrick's IV and V) with photodamage . Both procedures induced increasing amounts of types I and III collagen. However,
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