The Role of Chemical Peels and Other Superficial Resurfacing Procedures
Gary D. Monheit, M.D.
Associate Professor
Department of Dermatology
University of Alabama at Birmingham
Birmingham, Alabama

The explosion of interest in chemical peeling and laser resurfacing on the part of dermatologist has paralleled the general public’s interest in acquiring a youthful appearance by rehabilitating photoaged skin. The public’s interest has been further heightened by advertising for cosmetic agents, over the counter chemicals and treatment programs that have entered the general market of products meant to rejuvenate skin and erase the marks of sun damage and age. Most of these over the counter home do-it-yourself programs have been tried by patients and by the time they consult their plastic surgeon, cosmetic surgeon, or dermatologist, they are ready for a more definitive procedure performed with either chemical peeling or laser resurfacing. It is the obligation of the physician to analyze the patient’s skin type, degree of photoaging skin, and thus prescribe the correct facial rejuvenation procedure that will give the greatest benefit for the least risk factors and morbidity. The cosmetic surgeon should have available for his consumer the options of medical or cosmoceutical topical therapy, dermabrasion, chemical peeling, and lasers available for selective skin destruction and resurfacing. Each of these techniques maintains a place in the armamenteria of the cosmetic surgeon to provide the appropriate treatment for each individual patient and his specific problem.

The approach to photoaging skin has expanded beyond a one-stage procedure to now include preparatory medical therapy and post-treatment cosmoceutical topical therapy to maintain results and prevent further photodamage. Thus, the dermatologist’s office has become not only a surgical treatment session, but also an educational setting for skin protection and care and a marketplace for the patient to obtain the necessary topicals for skin protection. It is up to the dermatologist, cosmetic surgeon, plastic surgeon to fully understand the nature of skin and sun damage, protective techniques available, and active agents that work as cosmoceutical preparations. Having available multiple procedures to solve these problems will make his patients better candidates for the right procedure to restore and rehabilitate their skin.

Chemical peeling involves the application of a chemical exfoliant to wound the epidermis and dermis for the removal of superficial lesions and improve the texture of skin. Various acidic and basic chemical agents are used to produce the varying effects of light to medium to deep chemical peels through differences in their ability to destroy skin. The level of penetration, destruction and inflammation determines the level of peeling. The stimulation of epidermal growth through the removal of the stratum corneum without necrosis consists of light superficial peel. Through exfoliation, it thickens the epidermis with qualitative regenerative changes. Destruction of the epidermis defines a full superficial chemical peel inducing the regeneration of the epidermis. Further destruction of the epidermis and induction of inflammation within the papillary dermis constitutes a medium depth peel.1 Then, further inflammatory response in the deep reticular dermis induces new collagen production and ground substances which constitutes a deep chemical peel. These have now been well classified and usage has been categorized for various degenerative conditions associated with photoaging skin based on levels of penetration. The physician, thus, has tools capable of solving problems that may be mild, moderate or severe with agents that are very superficial, superficial, medium depth, and deep peeling chemicals. The physician must choose the right agent for each patient and condition.

Indications and Patient Selection
Analyzing the patient with photoaging skin must take into account skin color and skin type as well as degree of photoaging. Various classification systems have been available and I would like to present a combination of three systems that would simplify and help the physician define the right program or therapeutic procedure for his patient. The Fitzpatrick skin type system classifies degrees of pigmentation and ability to tan using a graded I through VI. It prognosticates sun sensitivity, susceptibility to photodamage, and ability for facultative melanogenesis (one’s intrinsic ability to tan).2 In addition, this system classifies skin as to its risk factors for complications during chemical peeling. Fitzpatrick divides skin types I through VI, taking into account both color and reaction to the sun. Skin type I and II are pale white and freckled with a high degree of potential to burn with sun exposure. Three and four can burn but usually is an olive to brown coloration. Five and six are dark brown to black skin that rarely ever burns and usually does not need sunscreen protection (Table I). The patient with type I or II skin with significant photodamage needs regular sunscreen protection prior to and after the procedure. He, though, has little risk for hypopigmentation or reactive hyperpigmentation after a chemical peeling procedure. The patient, though, with type III through VI skin has a greater risk for pigmentary dyschromia – hyper or hypopigmentation, after a chemical peel and may need pre and post-treatment with both sunscreen and bleaching to prevent these complications.3 Pigmentary risks are generally not a great problem with very superficial and superficial chemical peeling, but may become a significant problem with medium and deep chemical peeling.

The Glogau system classifies severity of photodamage, taking into account the degree of epidermal and dermal degenerative effects.4 The categorization is I through IV, ranging from mild, moderate, advanced and severe photodamaged skin. These categories are devised for therapeutic intervention. Category I in young individuals or minimal degree photodamage should be treated with light chemical peeling and medial treatment. Category II and III would entail medium depth chemical peeling while category IV would need those modalities listed plus cosmetic surgical intervention for gravitational changes (see Table II).

Monheit and Fulton have devised a system of quantitating photodamage and have developed numerical scores that would fit into corresponding rejuvenation programs.5 In analyzing photodamage, the major categories include epidermal color with skin lesions and dermal with textural changes. Dermal changes include wrinkles, crosshatched lines, sallow color, leathery appearance, crinkly thin parchment skin, and the pebblish white nodules of milia. Each of these is classified, giving the patient a point score, 1 through 4. In addition, the number and extent of lesions are categorized from freckles, lentigenes, telangiectasias, actinic and seborrheic keratoses, skin cancers, and senile comedones. These also are added in a classification system 1 through 4 and the final score results are tabulated. A total score of 1 through 4 would indicate very mild damage and the patient would adequately respond to a five-step skin care program including sunscreen protection, retinoic acid, glycolic acid peels and selective lesional removal. A score of 5 through 9 would include all of the above plus repetitive superficial peeling agents program such as glycolic acid, Jessner’s solution, or lactic acid peels. A score of 10-14 would include medium depth chemical peeling, and a score of 15 or above would include deep chemical peeling or laser resurfacing. The patient thus could understand during the consultation his degree of photodamage and the necessity for an individual peeling program. (See Table III)

The chief indications for chemical peeling are associated with the reversal of actinic changes such as photodamage, rhytides, actinic growths, pigmentary dyschromias, and acne scars.8 The physician thus can use his classification systems to quantitate and qualitate the level of photodamage and prescribe the appropriate chemical peeling combination.

Superficial chemical peeling
Superficial chemical peeling is truly an exfoliation of the stratum corneum or the entire epidermis to encourage regrowth with less photodamage and a more youthful appearance. It usually takes repetitive peeling sessions to obtain maximal results. These agents have been broken down into very superficial chemical peels, which will remove the stratum corneum only, and superficial chemical peels that will remove stratum corneum and damaged the epidermis also. It is to be noted that the effects of superficial peeling on photoaging skin is subtle and will not produce a prolonged or very noticeable effect on dermal lesions such as wrinkles and furrows. Agents used include: trichloroacetic acid 10 – 25 %, Jessner’s solution, glycolic acid 40 – 70 %, and salicylic acid-betahydroxy acid.9 (Table IV) Each of these agents has its own characteristics and methodology and a physician must be thoroughly familiar with the chemicals, methods of application, and the nature of healing. The usual time for healing is from one to four days depending on the chemical and its strength.

Very light peeling agents include low concentrations of glycolic acid, 10% trichloroacetic acid, and 20% salicylic acid, a betahydroxy acid. Glycolic acid is an alpha hydroxy acid derived from organic products and pH dependent to produce a superficial chemical peel through Keratolysis. Its intensity is dependent on concentration ranging from 10%-70%.

Salicylic acid, called a beta hydroxy acid molecule, is a salicylate derivative in ethanol solution used in concentrations 20%-40%. Jessner’s solution is a combination of these chemicals – resorcinol, salicylic acid and lactic acid. It is used as a superficial chemical peel for photoaging skin. Lactic acid is an alpha hydroxy acid useful in this combination.

TCA is the most versatile of all peeling agents as its concentration correlates directly with the depth of penetration and thus the degree of destruction within the skin. The concentration is usually compounded in a weight per volume measurement. It is important to distinguish this from the volume per volume formulation as the concentrations do not correlate. Most of the medical literature concerning TCA peeling uses a weight per volume measurement. TCA is usually standardized as an aqueous solution though it has been formulated as cream or paste. The author feels there is no distinct advantage to these formulations.

TCA destroys epidermis and partial dermis through keratocoagulation and protein precipitation, producing a white coating referred to as frosting. The degree of whitening or frosting can be correlated to penetration of the TCA within the epidermis and related to the depth of the peel. Level I frosting has the appearance of erythema with a streaky white frosting, which indicates superficial penetration. Level II frosting is a white enamel color with no erythema. Level III indicates the deepest penetration and is usually found with full medium depth peels through the epidermis with superficial dermal destruction.9

It is important to note that TCA applications are cumulative increasing penetration and peel depth with more quantity applied, even in low concentrations. Overcoating will always produce a deeper peel so that once the desired level of frosting is obtained, no further acid should be applied. Ten to twenty percent trichloroacetic acid will produce a light whitening or frosting effect on the skin with a result of sloughing of the upper one-third of the epidermis. Before this peel, the skin is prepared by washing the face thoroughly and using acetone, which removes surface oils and excessive stratum corneum. The trichloroacetic acid is applied evenly with either saturated 2 x 2 gauze, or a sable brush and it usually takes fifteen to forty-five seconds for the frosting to become evident. This would be categorized as a level I frosting with the appearance of erythema and streaky whitening on the surface. Level II and III frosting is seen in medium-depth and deeper peels. (Fig I) The patient experiences stinging and some burning during the procedure, but very rapidly this subsides and the patient then can resume normal activities. There is erythema and resulting desquamation which can last anywhere from one to three days. Sunscreens and light moisturizers are permitted and care is minimal in this superficial chemical peel.

Repetitive superficial TCA peels are useful for treatment of dyschromias and superficial skin lesions such as lentigines, ephelids, and thin seborrheic keratoses as well as fine surface texture. TCA as a superficial peel is best used in aqueous form with a concentration of 15%-25%. The peel should be repeated in 2-4 weeks and accompanied by home skin care products such as glycolic acid emollients, ascorbic acid to peel preparations and retinoids.

My favorite peel for photoaging is the Jessner’s solution peel. It is an inflammatory peel causing keratinocytes of the epidermis as well as inflammation. It causes mild erythema and peel for 2-4 days and should be repeated monthly. Jessner’s solution is a combination acid – escharotic which has been used for over one hundred years in the treatment of hyperkeratotic skin disorders. (Table V) It has been used as part of acne treatment for the removal of comedones and inflammatory acne activity. Its use as a superficial peeling agent performs as an intense keratolytic agent. The application is similar to superficial TCA application with wet gauze, sponges, or a sable brush, producing an erythema with blotchy frosting. Tentative applications are done on an every-other-week basis and the levels of Jessner’s solution coatings can be increased with repetitive applications. The visual endpoint produces a predictable outcome with epidermal exfoliation and regrowth. The superficial Jessner’s peel is a relatively inflammatory peel and thus useful for mild photoaging textural changes. It, though, can produce post inflammatory hyperpigmentation, which limits its usefulness for melasma and dyschromias. This usually occurs within two to four days and is treated with mild cleansers, moisturizing lotion, and sunscreen protection.

Alphahydroxy acids
Alphahydroxy acids, specifically glycolic acid, have become the wonder drug of the early 90’s with promises of skin rejuvenation with home use and topical therapy. Hydroxy acids are found in foods such as glycolic acid as naturally present in sugar cane, lactic acid in sour milk, malic acid in apples, citric acid in fruits, and tartaric acid in grapes. Lactic acid and glycolic acid are widely available and can be purchased for physician use. Glycolic acid is found in unbuffered concentrations of twenty to seventy percent for use as a superficial chemical peel. Weekly or biweekly applications of twenty to seventy percent unbuffered glycolic acid treatments have been used for wrinkles by applying the solution to the face with a cotton swab, a sable brush, or saturated 2 x 2 gauze. The time of application is critical for glycolic acid, as it must be rinsed off with water or neutralized with 5% sodium bicarbonate after two to four minutes. Mild erythema may occur for an hour with slight stinging and minimal result in scaling. Superficial wrinkle reduction and removal of benign keratoses have been reported from repeated applications of these peeling solutions.10

Many proprietary forms of glycolic acid have emerged on the marketplace with novel approaches to limit the burning and stinging such as buffering the acid and altering the pH and pKa. Though many of these prepackaged treatments are elegant and simple to use, the physician should be concerned over the efficacy as the peel is pH dependent. The strength of the product is dependent on available free acid, which is limited with buffers and higher pHs. I find it most practical to use concentration as the parameter for patient comfort and begin with 20% glycolic acid peels and gradually work up to the more potent concentrations of 50 and 70% as the patient tolerates the procedure. Using the generic product makes the peel reproducible and comparable with the percentage glycolic acid refined in the medical literature. Using proprietary peels that are buffered or esterified, the pH is greatly changed and though the patient may be more comfortable, the product may not have the same results as similar generic concentrations. As a pH dependent peel, I find the generic forms more reliable. If there is a question about efficacy, always ask what the pH is for equivalent results.

The peel is uneven in that there is no visible endpoint. It is a time-dependent peel which must be neutralized to stop the reaction.

Salicylic acid peeling or as commonly called, the ß-Hydroxy Acid peel, is unique in that it is a lipophilic agent formulated in ethanol. It is a non-inflammatory superficial peeling agent creating Keratolysis of the epidermal cells and sebaceous glands. Used as a 20-30% solution, it produces a white color, which is not a true frosting but rather a precipitation of salicylic acid crystals.

This peel is especially useful in the treatment of active acne, comedones and pores. Its lipophilic character targets sebaceous glands, pores and comedones with active crystals penetrating the skin surface. (Fig II) The peel will produce mild desquamation with little erythema and healing within 1 to 3 days. The effect in pores may continue for 5-7 days as penetrant crystals remain active with the pilosebaceous units. This superficial peel is the least inflammatory and thus can be used safely on those patients with darker skin. It is also an effective adjunct agent used for melasma because there is little risk of post inflammatory hyperpigmentation. It is also a very effective peel for acne, comedones and pores because of its lipophilic constitution. The peel produces a frosting which is the result of crystal precipitation. This splotchy frosting is the endpoint. It does not require neutralization though cool water soaks will add to patient comfort. It can be purchased from a chemical supply house in generic form such as Dermatologica Lab Supply, Council Bluffs, Iowa, or as a proprietary peel package called The Beta Lift.

Preparation for the peel includes the daily use of retinoic acid up to six weeks prior to the peeling event.11 There are available various strengths of retinoic acid on the market, and one must use a weaker formulation for sensitive skin and a stronger formulation for significant photodamaged skin. The preparation Renova has been approved by the FDA for the treatment of photoaging skin and wrinkles. It is more adept for usage with aging skin as the retinoid is suspended in a moisturizing vehicle. It is available in 2 concentrations: .02% and .05%. The more irritating Retin A acne preparations should be avoided because of irritation. Other OTC “retinol” products are in cosmetics and moisturizers but of less clinical value than the prescription drug.

A retinoid dermatitis may ensue a week or two weeks after initiation of the agent. One should not perform a peeling procedure with retinoid dermatitis present as the inflamed skin may develop problems with healing or even post operative complications. The dermatitis should subside by decreasing treatment so that the skin does not appear inflamed when the chemical peel is performed.12 The use of tretinoin prior to a chemical peel will enhance peel solution absorption and promote an even and uniform peel.13

Superficial chemical peels can be used for comedonal acne and post inflammatory erythema or pigmentation from acne, treatment for mild photoaging skin – Glogau I & II, and the treatment of melasma.

To treat melasma effectively, the skin must be pretreated and post treated with sunscreen, hydroquinone 4 to 8 %, and retinoic acid. Hydroquinone is a pharmacologic agent that blocks the enzyme tyrosinase from developing melanin precursors for the production of new pigment. Its use essentially blocks new pigment as the new epidermis is healing after a chemical peel. It is thus necessary to use when peeling for the treatment of pigmentary dyschromias and also when using chemical peels in type III – VI Fitzpatrick’s skin, the skin type most prone to developing pigmentary problems.14

When using superficial chemical peels, the physician must understand that repetitive peeling will not summate into medium depth or deep peels. A peel that does not effect the dermis will have very little effect on textural changes that originate from dermal damage. The patient must understand this preoperatively so that he will not be disappointed with his results. On the other hand, repetitive peeling procedures are necessary for maximal benefits to be obtained with superficial chemical peeling. These are timed weekly or every other week for a period of six to eight chemical peels and enhanced by the appropriate cosmoceutical agents. The ease of the procedure with little down-time makes these “lunch time” chemical peels a favorite with the baby-boomers who will not take time off.

Superficial chemical peels are used in concert with other non-invasive procedures to produce safe and effective results with little or no downtime. These complementary procedures include:
1. Cosmoceutical agents – retinoids, glycolic acid lotions, bleaching agents and home care exfoliants will enhance the results from a solitary peel and maintain the results. An appropriate sunscreen is very important. There are many other materials that have various claims of rejuvenating photoaging skin such as ascorbic acid, vitamin E, copper peptides and other antioxidants. The jury is still out on whether these are truly efficacious.
2. Skin fillers will augment deeper rhytids and atrophic tissue so that peels can then refine the surface. Using collagen, cosmoplast or hyaluronic acid products will smooth deeply wrinkled skin which peels cannot change.
3. Botox is used for the relaxation of dynamic wrinkles, especially in the glabella, forehead and crow’s feet. Injected prior to medium or deep peeling procedures will enhance the final results. Immobilizing the dynamic wrinkle will further lighten the dermal collagen remodeling in these areas producing a better peeling result.

Peeling will not correct granulation changes or problems with excessive skin. If a patient has a need for rhytidectomy or blepharoplasty, these procedures should precede the peel procedure.

Other alternative resurfacing procedures are currently available for rejuvenating photoaging skin. Non-ablative laser subsurfacing is a conservative method for regenerating dermal collagen without destroying the epidermis. It will thus control damage to the dermis, spare epidermal damage and create thermal contracture and collagen remodeling without epidermal destruction. These lasers either target water with wavelengths from 1300 to 1450 or are flash lamp vascular lasers at 585 nm. wavelength. The 1320 Nd:YAG laser has had more objective studies to document positive results. These are conservative results on photoaging skin that require multiple treatments and maintenance therapy. It is most successful in treating fine lines on eyelids and crow’s feet. These lunchtime procedures will produce very conservative results and not very helpful for more advanced photoaging skin. Fine lines and crêpe eyelid skin can be improved with a 1320 Nd:YAG non-ablative laser. The products are numerous but fall into the following categories:

Product	Type/Wavelength	Target	Special Features
Smooth Beam Candela	Diode/1450	Water	Protective Cooling
CoolTouch CoolTouch Corp	1320 Nd:YAG	Water	Protective Cooling
Quantum SR Lumenis	IPL Broadbeam	Pigmented vessels	Non-coherent pulsed light
N-Lite Medical Alliance	595 pulsed laser	Vessels	Vascular photothermolysis
Thermacool	Infrared 1064-1540	Water, Collagen	Radiofrequency system

Each of these systems is different in technology and application and thus requires training and instruction. The tissue lightening effect of these procedures may produce results on eyelids with early blepharochalasis those patients not yet ready for blepharoplasty. They may also be used as a skin adjunctive procedure after blepharoplasty.

Intense pulsed light is a non-laser light source with a broadband of absorption producing conservative yet safe treatment for vascular and pigmentary sequellae of photoaging. Fewer than six treatments at three week intervals will destroy lentigenes and ephelides, clear rosacea flushing and photoaging, telangiectasias and have a mild effect on fine lines and pores. Its effect is noted on mottled coloration such as seen with poikiloderma and weathered skin. This procedure also depends on repetitive treatments and needs maintenance follow up treatments for lasting results.

Microdermabrasion is a specific treatment for correcting the rough texture of photoaging skin. Aluminum oxide crystals are blown onto the skin surfaced in a closed system with suction. This exfoliates the stratum corneum and upper epidermis. It produces a similar injury pattern as a very superficial chemical peel but creates the damage with mechanical rather than a chemical burn. There is less inflammation but also less visible results. The patient finds the tactile texture of the skin is greatly improved with a smoothness superficial lasers and/or peels do not fully achieve. This procedure is a repetitive lunchtime treatment which must be repeated and is used in combination with other resurfacing procedures.

Superficial chemical peeling thus is one of the available cosmetic procedures used in concert to produce results that are greater than it can produce alone. It is best to present a package of treatment modalities that are a treatment plan for changing skin surface. These include:
1. Cosmoceutical agents and sunscreens
2. Superficial chemical peeling
3. Lasers – vascular and non-ablative
4. Intense pulsed light
5. Microdermabrasion
6. Botox
7. Dermal filling agents – collagen or hyaluronic acid products
With patients demanding no downtime treatments with results that will reverse photoaging skin, it is the physician’s obligation to have available appropriate treatment. Though chemical peeling is the cornerstone for all cosmetic skin resurfacing, the other treatment modalities should be available. It is the responsibility of the treating physician to have a thorough knowledge of all of these tools to give each patient the correct treatment his condition warrants.