Scar therapy: Classification by morphology, etiology determine laser choice

Key Points

Scar therapy has advanced alongside the development of laser technology. Now, several options exist for various types of scars. Determining the proper treatment for each scar depends on the type of scar being treated.

Just using the term "scar" or "cicatrix" does not give any indication as to which type of laser or light device to use. Scars can be classified as to their clinical morphology, or their etiology.

Scar types can include: hypertrophic; keloid; atrophic; hypopigmented; hyperpigmented, acne scars, including ice pick, boxcar and rolling types; surgical scars; and erythematous scars. Some even consider striae to be in this category, due to the histologic similarity to an atrophic scar.

"Laser scar revision" is still in a state of development, as new advances in laser technology continue to occur. We will discuss the currently available laser devices and their most promising results for scar therapy.

Pulsed dye lasers

Pulsed dye lasers (PDL) have received much attention in scar treatment due to their affinity for hemoglobin. Absorption by hemoglobin of yellow (585 nm, 595 nm) wavelengths of light has given these devices an advantage when treating erythematous scars.

Several studies have shown improvement in both hypertrophic and keloidal scarring after several treatments with the pulsed dye laser.

These studies have not only demonstrated improved cosmesis, but also improvement in symptoms related to these types of scars, including dysesthesias and pruritus.

Very thick keloidal scars may require the addition of intralesional cortisone along with pulsed dye laser treatment.

Treatment at low fluences with short pulse widths has been most successful. Treatments intervals should be at least one month in length, allowing for complete resolution of the purpura or any associated hyperpigmentation.

PDL treatments can be initiated as early as the day of suture removal (Nouri et al. Derm Surg. 2003).

The mechanism of action of the pulsed dye lasers in the treatment of scars is still unknown. Proposed theories include collagenolysis and, possibly, disruption of vascular structures leading to decreased deposition of collagen.

Pulsed dye lasers can be used for any erythematous scar or striae. Newly formed and erythematous scars respond more rapidly than older, mature scars. Erythematous acne scars have also been treated with success with pulsed dye lasers, with improvements in both texture and color.

Dual-wavelength lasers

Dual-wavelength lasers (Cynosure, Cynergy), employing both 595 nm and 1064 nm, offer the added benefit of additional collagen remodeling (1,064 nm) as well as treatment of the erythema, and, hence, may prove to be more efficacious than pulsed dye treatment alone.

Other lasers that have been reported to improve erythematous scars include the frequency-doubled Nd:YAG devices (532 nm; Gemini, Iridex).

Intense pulsed light devices also emit at the yellow wavelengths and can be helpful in the therapy of erythema as well. Longer pulse widths and additional cooling can allow for more successful resolution of erythema while offering more epidermal protection.

Traditional spot scanning

Traditional large spot scanning CO₂ (10,600 nm) and erbium:YAG (2,940 nm) lasers have been the mainstay of therapy for atrophic, non-pitted acne scarring.

Since the introduction of the fractional devices, their popularity has decreased due to the downtime associated with treatment and the inability to treat the darker skin types. However, some patients still prefer a single-session treatment.

Patients with lighter skin types fare better with these traditional ablative resurfacing lasers, as dyspigmentation is the most common side effect. Typical improvements with the CO₂ laser are in the range of 50 percent to 80 percent with a single treatment.

Downtime is four to 10 days (shorter with Er:YAG), with the possibility of prolonged erythema for up to six months.