> A review of laser treatment of acne scars

what is laser?

Laser is an acronym for light amplification by stimulated emission of radiation. Laser uses light energy to produce heat. This heat can vaporize tissue and its water containment. Hypertrophic scars and keloids in which excess collagen tissue is accumulated in dermis could be affected by laser- generated-heat. However, other types of scarring such as atrophic scars do not benefit as much due to the fact that collagen loss is substantial. Collagen bundles arrangements is lost, that is another factor less affected by ablative types of laser.

Ablative versus non ablative

Ablative laser treatments are overall more aggressive in terms of severity and they can cause epidermal burning whereas non ablative laser is less invasive and conduct heat to deeper dermis causing collagen synthesis so this type could be more effective when atrophy and collagen degradation is the goal. Epidermis remains intact with non ablative laser treatments. Non ablative laser is used for more delicate procedures such as under eyes lines and wrinkles and other facial wrinkles as well as superficial acne scars and other types of scarring. Recovery time for ablative laser is much longer and could be as long as six to eight weeks. Acne scar type is another factor to consider. Rolling acne scars may not benefit as much from short pulse laser as icepick and boxcar acne scars.

Laser resurfacing is a recent addition to the armamentarium of options for acne scarring. Lasers are relatively safe and effective options that remodel the skin to improve its appearance. In addition to lasers, numerous modalities can be used to treat acne scars, including excision, subcision, cryosurgery, dermal fillers, chemical peels, and silicone sheeting compression. Ice-pick scars usually extend too deep into the dermis to be reached by conventional treatments and may require a punch modality for removal. For rolling scars, therapies should be aimed at treating the irregular underlying anchoring between the dermis and subcutis. Therefore, laser revision is usually limited to shallow boxcar and superficial scars.

Ablative laser resurfacing with either a carbon dioxide or Er:YAG laser may be beneficial for acne scars. After the initial treatment, allow the skin to heal, which may take 6-8 weeks. The postoperative erythema may last for up to 12 weeks. The scars can be treated with additional laser sessions to achieve the desired dermal remodeling and skin appearance.

As stated, resurfacing with a carbon dioxide laser can carry many potential risks such as delayed post-treatment hypopigmentation and scarring as well as prolonged healing after the procedure. This ablative laser can be effective alone for scarring after acne, but the risks must be considered before a patient undergoes this procedure. To enhance the selectivity of the carbon dioxide laser, some have tried combining it with an erbium laser, which is taken up more preferentially than the carbon dioxide beam. The erbium laser's cutaneous destruction is much more localized because the energy dissipates quickly within the targeted tissues. This procedure is more selective and less damaging to the skin than the carbon dioxide laser resurfacing.

Co2 fractional ablative laser is a combination method which combines conventional co2 laser with fractional photothermolysis. One study indicates its sucess in treating acne scars. Side effect appear to be transient and overall improvement in acne scars was shown to be 25-50%.

The carbon dioxide laser can be used to first treat the scar, followed by irradiation with an erbium laser to further remodel the ablated, carbon dioxide–treated tissue. This speeds the wound healing process and reduces the potential complications associated with only using a carbon dioxide laser.

In contrast to ablative resurfacing, non ablative lasers do not noticeably disrupt the skin's epidermis, but they deliver thermal energy and damage the underlying dermis. These lasers induce collagen remodeling and production, which is predominantly collagen type III. In time, the collagen expression changes to contain a greater proportion of type I collagen. With these lasers, clinical improvement usually requires more than one treatment and results can continue to improve months after the laser treatments have been completed. Combined 585/1064 nm laser showed to be more effective for deep boxcar scars compare to that result of YAG laser. One study has demonstrated that acne scar impovement of about 30% in severity using a non ablative short pulse 1064 laser.

| American Academy of Dermatology | Plastic Surgery and Laser Treatments | Stretch Marks in Pregnancy | Aging Skin | Skin Scarring | C02 Laser for Acne Scars | Cutaneous Laser Resurfacing | Laser and Collagen Remodeling |

Effect of laser treatments on stretch marks is still controversial. Some plastic surgeons claim that laser could fill up the dermal layer with laser stimulated collagen synthesis. However, there is no clinical data support the idea. As stretch marks are tearing in dermal layer, effectiveness of most types of laser on dermal consistency is not very clear. Non ablative laser treatments show less epidermal effect and conduct the light energy to the dermal layer. However, its effect in correction of dermal tearing and rearrangement of collagen bundles may not be as expected.