Several laser and light devices can reduce the erythema and redness associated with burn and traumatic scars and also possibly soften such scars and make them more flexible. Among these devices are the 585- to 595-nm pulsed dye laser (PDL), the 532-nm potassium titanyl phosphate (KTP) laser, the 1064-nm neodymium:yttrium aluminum garnet (Nd:YAG) laser, and the 500- to 1200-nm intense pulsed light (IPL) device. All of these are safe and well-tolerated, with typically no downtime after treatment. The PDL is the workhorse for red scars, given its long history and outstanding safety profile. More recent iterations of the KTP are also increasingly used for this purpose. A series of vascular laser or light treatments are usually required for best results. The most common concern, postinflammatory hyperpigmentation, remains rare, except when aggressive settings are employed or tanned or darker-skinned patients are treated.
The first selective device that was highly successful for so-called “selective” treatment of vascular lesions, including pink, red, and purple scars, was the pulsed dye laser (PDL). The earliest version of this device became commercially available 40 years ago. Other laser and light devices specific for redness are the potassium titanyl phosphate (KTP) laser (532 nm), the 1064-nm neodymium:yttrium aluminum garnet (Nd:YAG) laser, and intense pulsed light (IPL) devices. New iterations of the KTP laser come with larger spot sizes and appropriate setting ranges for targeting erythematous scars, much like the PDL. The 1064-nm laser is generally reserved for deeper vascular lesions and requires precise skin cooling to avoid injuring the overlying scar, thereby inadvertently stimulating formation of a hypertrophic scar; as a consequence, the 1064-nm device is less frequently employed for the treatment of redness in scars. Basic IPL devices emit a light at frequencies ranging from 500 nm to 1200 nm and can be useful for treating both red and brown discoloration. However, IPLs are not truly selective for erythema, and more treatments can be required than with other lasers for mitigating scar-related redness.
Since it is the most used vascular device for scar treatment, we will primarily discuss the PDL. The PDL emits wavelengths of 585 nm or 595 nm, both of which are close to the 577-nm secondary absorption peak of oxyhemoglobin. The energy from the PDL is preferentially taken up by red blood cells, resulting in the destruction of the associated vessels. As with the other selective devices, thermal collateral damage to the surrounding healthy tissue is limited. This is, of course, particularly important when treating scars, as residual thermal injury could result in scar exacerbation.
The original PDL emitted a wavelength of 577 nm, but over time it was modified using slight changes in the dye lasing medium. Newer PDLs tend to emit at longer wavelengths, earlier at 585 nm and more recently at 595 nm, to ensure slightly less absorption in oxyhemoglobin, slightly deeper penetration of the laser ...