Acne scarring presents a challenging aesthetic problem to the aesthetic practitioner. According to the available evidence, what types of laser have been shown to be more appropriate and why? Discuss your options in relation to patient, scar, technology factors and side effects.
Dr Ralitsa Hristova
ID: 140550188 1769 words
Visible skin scars or lesions can result in serious psychological impairment. Recent survey shows that individuals with acne scars, melasma, port -wine stains etc. felt that the skin lesions exerted negative effects on their social and sexual relationships, self-esteem and their ability to get a job. (1)
During the teenage years hormonal changes stimulate the sebaceous glands to produce more sebum. Skin in the puberty is getting more greasy and some pores get clogged by oil and dead cells. Bacteria as Propionibacterium acnes may infect blocked sebum causing spots(pimples and papules).Inflammation may develop in nearby skin. Most affected are people between 12 and 25 years, boys more commonly than girls.
The inflamed spots will heal but sometimes in severe cases hyperpigmentation remains as post-inflammatory sequelae- more noticeable in Fitzpatrick type III, IV skin. In other cases, inflamed spot leave a small pitted scar which do not fade and mark the skin of an adult individual. With the age acne scars are getting more prominent and visible because our skin loses collagen.(2)
Tabl. 1 (AAD Acne scars: treatment and outcome)(3)
|Treatment for depressed acne scars|
|Acne scar surgery|
|Resurfacing; laser therapy, chemical peeling, dermabrasion, microdermabrasion|
|Collagen-induction therapy,aka needling|
Tabl. 2 (AAD Acne scars:Treatment and outcome)
|Treatment for raised acne scars|
|Injections (corticosteroids, interferon, 5-FU,etc.)|
|Acne scar surgery|
|Scar creams and gels, silicone (dressing and bandages)|
Laser Therapy of acne scars
The most involved types of lasers in acne scar management are traditional Ablative lasers( CO2 & 2.94 Erb:YAG 10-200 microns) so called ‘Gold Standard’ in facial resurfacing, non-Ablative fractional( fractionated Erbium 600-1500 microns) and Ablative-fractional lasers( fractionated CO2 600-1500 microns).
Non-fractional CO2 ablative laser and Erbium laser (Ultrapulse CO2)emit light with a wavelength of 10,600 nm targeting the water molecules as chromophores. To ablate means surgically to remove tissues. Since, these lasers are not fractional dermis and epidermis are removed by the heat, creating an open wound that takes a longer time to heal (see first left red zone on the diagram fig.1).
Non-Ablative fractional laser technologies represented in the second areas of the diagram (Fraxel 1500 and fractionated Erbium) heat but do not ablate the tissues. Heating small columns of the deep skin layers promotes collagen synthesis and smoothing of the scars. Recovery period is shorter compare with ablative technologies.
Several new types of fractional ablative lasers were developed recently(see on right in diagram fig.1). The beam of these lasers is broken, fractionated. When it strikes the skin surface small areas between the beams leave intact.These small areas of untreated skin promote rapid recovery and healing with less complications.(4)
Fig. 1 (Dr.Jeffrey A. Rapaport)
In 1995 Ho and colleagues treated 25 patients with Ultrapulse CO2 laser 10 of them for acne scars. They published earliest study for ablative CO2 laser treatment and noted 25 % improvement in the group with acne scarring. When in 1998 Bernstein used a high energy,short pulsed CO2 laser he registered with two to six passes a great improvement of the surface contour in 30 out of 30 treated patients. All acne scar treated patients had greater than 50% improvement.(5)
Ablative lasers improve atrophic scars. CO2 laser vaporizes epidermis and papillary dermis in depth of 20-60 µm while the thermal necrosis extends another 20-50 µm.
Bernstein and colleagues studied side effects related to the use of CO2 laser. They have noticed elevated pigmentary changes in individuals with a darker skin type; 36% Alster and West, 17% by Waldorf and al.,2.8% Bernstein and al.(6)
Hypopigmentation and elevated sensitivity to cosmetic and medicinal products were registered in 4.8% of the patients post CO2 laser therapy.
Short term complications included erythema, pruritus,acneiform pustules and infections( Waldorf and al. reported 6.5%).
CO2 ablative laser is more effective compare with Er-YAG(erbium yttrium aluminum garnet)ablative laser but causing more side effects.
Er-YAG laser penetrates 10-20 µm and ablates tissue with a single pass of 5 J/cm2 fluence, while the residual thermal damage does not extend more than 15 µm. Recent trial from 2009 shows that short pulses of 300 microns pulse width with Er-YAG laser improve skin smoothness and extra-long pulses of 1500 microns pulse width improve skin smoothness and scar volume on skin type III- V (7).
Side effects associated with Er-YAG laser are milder compare with CO2 laser. Transient postoperative hyperpigmentation, postoperative erythema,peeling and crusting are observed.
Adverse effects of ablative lasers as prolong postoperative erythema and discoloration especially in darker skinned individuals led to development of a different type of light devices and lasers; Nonablative lasers.
With these devices we can induce a controlled damage of the collagen in the dermis sparing the epidermis in the same time. Collagen undergoes healing and remodeling under the sound epidermis resulting in improvement of skin and scar appearance.
Despite lower efficacy nonablative lasers also reduce the acne scarring.
Infrared (1320 nm- 1540 nm wavelength) and visible light (532 nm-green, 585 nm-yellow) lasers are the two types mainly used for nonablative treatment of acne scars.
Increasing the temperature with these lasers in the dermis is not sufficient to cause damage but stimulates some growth and inflammation factors as heat shock protein 70 ( HSP70) and TGF-β1 both taking part in inflammatory response and fibrogenesis.
Targeted chromophores of nonablative lasers are oxyhemoglobin and melanin in the blood vessels of the superficial dermis.
In an experimental study Prieto and al. used Q-switched 1064 nm Nd:YAG laser and demonstrated that sufficient heat conducted by heated blood vessels to the surrounding papillary and reticular dermis can induce expression of HSP70 and type I procollagen to remodeling the scar.
Furthermore, local ischemia of microvessels lead to release of collagenase causing a breakdown of collagen in the scar. That way possible Q switched laser improves atrophic and mixed pattern acne scars.(8)
Adverse reactions observed when using nonablative lasers are milder compare with resurfacing with ablative lasers. Postoperative erythema and mild-to moderate pain are transient. Hyperpigmentation when are treated patients with skin type IV – V must be considered. It is a good choice of treatment for patients with atrophic acne scars, who cannot endure the prolonged recovery of resurfacing procedures.
Fractional photothermolysis (FP) is a new concept answering the need of modality to balance between side effects of ablative lasers and lower efficacy of nonablative. Broken, fractionated beam induce a thermal damage in a small 3D zones known as microthermal zones (MTZs).
Lasers with moderately absorbed wavelengths as 1410 nm, 1440 nm, 1540 nm are nonablative fractional lasers and do column like denaturation of dermis and epidermis. Microthermal zones (MTZ) are surrounded by non thermally damaged columns. Keratinocytes from uninjured tissue migrate to MTZ and replace the thermally injured tissue. They also eliminate the necrotic debris in a transepidermal fashion using the subepidermal clefting known as microscopic epidermal necrotic debris shuttle (MENDs). One week after the treatment MEND shuttling results in bronzing and scaling of the skin. In the next 3-6 months period a new collagen remodeling the MTZ.
FraxelTM is a nonablative FP laser the first and the most studied. It has incorporated tracking system to track the number and patterns of MTZ.
With this device epidermal healing is completed in the first 24 h which lower the possibility of infection or other complications.
CO2 FP is an ablative fractional laser. Histological analysis shows that ablative fractional resurfacing (AFR) results in ablation of microscopic columns in epidermis and dermis with variable thickness and depth depending on the pulse width and wavelength. Photothermal energy of these devices induce zones of coagulation and denatured collagen. Re-epithelization of these zones is very fast in 48 h post treatment.
Thirteen Asian patients who had Fitzpatrick skin type IV participated in a study and have been treated for atrophic acne scars with CO2 fractional laser ( Ultrapulse Encore Laser).
The study ( Manuskiatti and al.)shows a notable improvement of the smoothness and volume of the scars after 4 sessions over a 7-week duration. 85% of the patients had between 25-20% improvement with 6 months after treatment with short lasting PIH disappearing in 5 weeks.(9)
Most of the studies show certain efficacy and low grade of adverse effects of FP. While ablative lasers are associated with more severe side effects as bleeding, oozing and increased downtime, AFP are associated with mild reactions as erythema, slight pain, edema, slight skin scaling and bronzing. Topical anesthetics are recommended in some cases.
Postoperative care includes semi- occlusive dressing and use of moisturizers ( not occlusive ointments ). To minimise the risk of PIH patients are advised to use a sunscreen 30 + factor.(10)
The most unpleasant outcome of acne lesions is scarring. Acne scars can be raised or depressed. The architecture of the extracellular matrix is determined by metalloproteinase (MMPs) and tissue inhibitors of MMPs.
An imbalance in the ratio between these two factors results in the development of atrophic or hypertrophic scars. Diminished deposition of collagen cause formation of an atrophic scar, while exuberant healing response cause formation of a raised nodule of fibrotic tissue- hypertrophic scar.
The qualitative scarring grading system has 4 grades , where 1st grade are macular scars, they represent a problem of color, not of contour. Second grade are mild atrophic or hypertrophic scars not obvious from a social distance of 50 cm. Third grade are moderate obvious from 50 cm, and 4th grade are severe scars that are visible from greater than 50 cm social distance and cannot be easily covered with a make-up.
According to Goodman and al. nonablative lasers are useful to treat grade 2 scars, while ablative are indicated in grade 3 and 4 acne scars.(11)
The efficacy of ablative resurfacing with CO2 or Erbium lasers are demonstrated in many studies. Atrophic facial scars show improvement of 50-80%. All ablative lasers have a prolonged downtime and adverse reactions.
Nonablative skin technologies decrease the side effects and the need of postoperative care. These technologies are developed as a safe alternative to ablative lasers, causing a controlled thermal injury to the dermis followed by neocollagenesis and scar remodeling. However, the efficacy of these lasers is lower and the results are not as impressive as the ablative resurfacing.
Fractional photothermolysis devices are newest modalities combining the good results of ablation and less side effects of nonablative devices.
Reepithelialization is very rapid form uninjured columns of tissue gidding the relatively rapid recovery and reduced downtime.
Patient selection, medical history,premedication, and postoperative care are important factors for a good outcome.
- Finlay AY, Khan GK. Dermatology Life Quality Index (DLQI) – a simple practical measure for routine clinical use. Clin Exp Dermatol 1994; 19:
- Original Author Dr. Tim Kenny Document ID: 4190(v41)
- AAD Acne scars :Treatment and outcome Am Acad Dermatol 2008;59:659-76.
4.Dr.Jeffrey A.Rapaport- Ablative Fractional CO2 (Mosaic E-CO2 and Fraxel Repair) and non-Ablative fractional Erbium Laser (Fraxel 750, 1500 Fraxel Restore)
- Bernstein LJ, Kauvar AN, Grossman MC, Geronemus R. Scar resurfacing with high-energy, short-pulsed and flash scanning carbon dioxide lasers. Dermatol. Surg. 24(1), 101–107 (1998).
- Bernstein LJ, Kauvar ANB, Grossman MC, Geronemus RG. The short- and long-term side effects of carbon dioxide laser resurfacing. Dermatol. Surg. 23, 519–525 (1997)
7.Wanitphakdeedecha R, Manuskiatti W, Siriphukpong S, Chen TM. Treatment of punched-out atrophic and rolling acne scars in skin phototypes III, IV, and V with variable square pulse erbium:YAG laser resurfacing. Dermatol. Surg. 35(9), 1376–1383 (2009)
- Prieto VG, Diwan AH, Shea CR, Zhang P, Sadick NS. Effects of intense pulsed light and the 1,064 nm Nd:YAG laser on sun-damaged human skin: histologic and immunohistochemical analysis. Dermatol. Surg. 31(5), 522–525 (2005).
- Manuskiatti W, Triwongwaranat D, Varothai S, Eimpunth S, Wanitphakdeedecha R. Efficacy and safety of a carbon-dioxide ablative fractional resurfacing device for treatment of atrophic acne scars in Asians. J. Am. Acad. Dermatol. 63, 247–283 (2010).
- Sherling M, Friedman PM, Adrian R et al. Consensus recommendations on the use of an erbium-doped 1,550-nm fractionated laser and its applications in dermatologic laser surgery. Dermatol. Surg. 36(4), 461–469 (2010).
- Goodman GJ, Baron JA. The management of postacne scarring. Dermatol. Surg. 33, 1175–1188 (2007).