Treatment of acne scars with Er: YAG lasers

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Treatment of acne scars - laser acne scar removal

The Er: YAG lasers are the best lasers for the treatment of acne scars. This is the best procedure for acne scar removal. The benefit of Er:YAG lasers for superficial to moderate acne scar removal is based on the fact that these lasers produce less thermal damage compared to other types of laser. Since the short pulsed Er:YAG lasers have a water absorption coefficient that is 16 times greater than the CO2 laser, most of the energy of these lasers is absorbed by water in the tissue resulting in minimal optical penetration depth and thermal damage. The more limited penetration of these lasers into the skin results in a histo-pathological improvement that is less pronounced that those of CO2 lasers Er:YAG lasers penetrate 5 µm/pass deep into the skin as compared to CO2 lasers which effect a significant coagulation necrosis that is around 20–40 µm/pass deep. Never the less, the Er:YAG laser has shown much promise as an acne scar removal treatment especially in the treatment of mild to moderate superficial rhytides and scars, in fact it is the best form of laser treatment for treatment of acne scars which are not very deep.

A new laser technology for treatment of acne scars

This new technology in the infrared spectrum (2940 nm), and an energy fluence of 2.8 J/cm, has been proven to provide very precise ablation, because of its high selectivity to tissue water and negligible thermal damage. There is no doubt that the Er:YAG laser is the optimum ablative device for fine and superficial resurfacing of the skin, its characteristics of energy wavelength with maximal water absorption, a sufficiently short time duration (< 1 ms) of its action time, combined with sufficient energy fluence, make it the best procedure for laser acne scar removal.

As there is no sign of adjacent thermal injury (maximum temperature of 30 °C is achieved in the adjacent skin), pinpoint bleeding appears after several passes (4–5 passes depending on the spot size and energy fluence) with exposure of the dermo-epidermal junction, and the laser treatment is usually stopped.

Since bleeding is a problem in the treatment of deeper wrinkles with the Er:YAG laser, the end point of treatment is defined by a more superficial level. The main advantages of the Er:YAG over the CO2 laser are the reduced thermal damage, shorter recovery time, less postoperative erythema, and fewer anesthesia requirements.

In a comparative study in the treatment of facial rhytides, where Er:YAG lasers and CO2 lasers were used, there were no significant difference in postoperative erythema, pain, and healing time when equal depths of tissue coagulation and ablation were achieved with each type of laser. However, the same study showed that, with similar postoperative morbidity, the Er:YAG laser showed, in general, less efficacy.

Fine lines responded very well to this laser, whereas deeper rhytides showed a greater response to CO2 laser resurfacing. Another study on 21 subjects with facial rhytides showed relatively better wrinkle improvement with the CO2 laser, but quicker recovery with the Er:YAG lasers.

Benefits of Er.YAG lasers for the treatment of acne scars

The Er:YAG laser appears to be successful at improving mild to moderately severe photo-damaged skin, acne scars, post-surgical facial scars, and hypertrophic scars. It may improve photo-damaged skin in areas off limits to CO2 laser resurfacing, such as the neck, hands, and chest, if used by experienced hands.

The main areas where improvement is observed are:

  • Darker skin types (especially skin type V – Asian), which cannot be treated with other methods, can be treated more safely with the Er:YAG laser.
  • Removal of chicken pox scars where study results have shown improvement in 55% of patients.
  • Removal of more superficial acne scars where study results have shown improvement in 40% of patients.
  • Removal of fine facial wrinkles, especially in the periocular and perioral regions where skin is more delicate.
  • Improvement in facial and neck dyschromias, lentigines (as the abnormal pigment can be removed to the exact desired level).
  • Treatment of actinic keratosis.
The other advantages of the Er:YAG laser in skin resurfacing are the reduced healing time and reduced postoperative erythema involved. The treatment for acne scars with this laser technique is more or less similar to that of the CO2 laser, but different in the regard that the clinical endpoint is here well defined. The bleeding (laser treatment with CO2 does not cause bleeding as the blood vessels get concealed due to high thermal temperature) that occurs after reaching a certain depth is enough to alert the laser surgeon to the fact that he has reached the papillary dermis.

Pre- and Post - operative care

For the treatment of acne scars with Er:YAG laser treatment, patients are often instructed to use tretinoin cream 0.05% nightly for 2–4 weeks prior to laser treatment.

Because of the nonhemostatic laser, wet gauze compression for several minutes post-treatment is necessary. After laser treatment, topical semioccluded dressings “closed” technique) or topical moisturizers (“open” technique) are applied, as with CO2 laser treatment.

Two weeks after laser treatment, topical applicationhydroquinone 2–5%, tretinoin 0.05–0.1%, and hydrocortisone 1% cream is recommended for 2–4 weeks.

Complications of Er:YAG laser resurfacing

In general, the Er:YAG laser causes lower morbidity and fewer complications than the CO2 laser. There is less postoperative erythema, which lasts for 2–4 weeks.

Post-inflammatory hyperpigmentation is also transient.

Since these lasers penetrate to a more superficial level, late complications, such as hypopigmentation, are seen in fewer patients (4%) treated with the Er:YAG laser as compared to the CO2 laser.

The presence of bleeding during laser treatment forces the surgeon to discontinue laser treatment and therefore prevents serious complications from allowing the laser to penetrate too deep into the skin. Nevertheless, the risk of scarring and hypopigmentation could increase if the laser surgeon ignores the bleeding and seeks to achieve considerable ablation depths.

Combined Er:YAG/CO2 laser

With the therapeutic aim to produce the degree of granulation tissue and fibroplasia seen with the CO2 laser, and at the same time to reduce the zones of thermal damage (50–100 µm compared with 150 µm), a combination of a CO2 laser and an Er:YAG laser have been tried in the past.

Actually the modality seems to be quite ideal, the thermal effect of the CO2 laser is sufficient to stimulate collagen remodeling, whereas part of the thermal necrosis zone is removed, thus minimizing the time of the healing process.

Very few comparative studies have been published using this new combination of Er:YAG lasers and CO2 lasers. But in general, the preliminary results compare favorably with those produced by the CO2 laser alone, with reduced healing times and erythema duration.

More clinical and histological comparative studies are necessary in order to define the exact parameters of the modality for producing skin resurfacing with the least residual thermal damage, good clinical results and excellent recovery for more deeper skin defects.

Nevertheless Er:YAG lasers are the best laser procedures for treatment of acne scars when the scars are not very deep.

References:
  1. E. Papadavid,and A. Katsambas, “Lasers for facial rejuvenation: a review”, 2003, The International Society of Dermatology, 42, 480–487
  2. D. Railan, and S. Kimlmer, “Ablative treatment of photoaging”, Dermatologic Therapy, Vol. 18, 2005, 227–241


   
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