Introduction

Laser and light therapy is a constantly evolving and improving area within the medical field. Although lasers were initially developed with medical purposes in mind, the gradual shift has been towards cosmetics. The variety of lasers and light treatments available can treat such things as wrinkles, scars, vascular lesions, unwanted hair, pigmentary disturbances, tattoos and medical conditions such as psoriasis, vitiligo, and acne. There are a few general points in terms of laser and light therapy that will be discussed, after which more specific points will be made.

Complications are adverse events or responses to a therapy or procedure. Many complications that can arise are not laser specific; however, there are some complications that are more likely to arise with certain laser and light procedures. A more general discussion leading to a more focused discussion on complications within certain subsets of lasers will follow.

General considerations

It is beyond the scope of this chapter to discuss the specifics in setting up a laser unit. However, there are a number of medical–legal issues that can arise if laser treatments are done in unaccredited facilities, by untrained staff, or without the proper safety equipment.

Accreditation is a voluntary process by which a facility is able to measure itself against nationally recognized standards. There are several organizations through which a facility can accredit itself. The American Osteopathic Association (AOA), the Joint Commission on Accreditation of Health Care Organizations (JCAHO) and the Accreditation Association for Ambulatory Health Care (AAAHC) all accredit organizations and facilities.

Displaying certificates of accreditation serves as a reassurance to patients, the public, and to other healthcare professionals that a facility has met an independent standard of quality.

The geographic location of where treatments are done will determine the regulations of who can utilize a laser or light device. Each regulatory board has different rules. In some jurisdictions, only a physician may legally operate a laser or light device. Other jurusdictions require a certain amount of training and certification. Some require that a physician has evaluated the patient before the procedure is performed. It is up to the individuals involved to find out the established rules of their jurisdiction.

Eye protection within the workplace is mandated depending on location. In the US, guidance for protective eyewear is outlined by the American National Standards Institute (ANSI) Z136 series. This is published and constructed by the Laser Institute of America (LIA). In Europe, eye protection guidelines are outlined in the EN 207. Further suggestions include warning signs on the door to warn anyone entering the operating room.

Complications

The many mechanisms of action of various laser and light sources lead to the potential for many different complications. Some lead to more frequent and / or more serious complications. However, many laser and light devices work by the principles of selective photothermolysis, and thus these complications can be discussed together.

General complications

The most common complications of laser treatment are: burning, prolonged erythema, hypo- or hyperpigmentation, reactivation of herpes simplex virus, and acneiform eruption.

Burning can be a common complication of a variety of lasers. Burning can occur with the use of vascular, hair removal, and non-ablative rejuvenation lasers as well as intense pulsed light (IPL) devices. When a burn occurs, it is usually due to one of three possible causes: too high a fluence, too short a pulse duration, or insufficient epidermal cooling. Most lasers have initial recommended settings, which are fairly safe parameters with appropriate technique and adequate epidermal cooling. Depending on the severity of the burn, there is usually little that is required in terms of treatment. With only a slight burn, there may be prolonged erythema. With a more severe burn, however, blistering and scarring may develop. Occurrences of more severe hypertrophic scarring have been minimized with the advent of newer technology and the disuse of more scar-prone lasers such as the continuous wave argon laser.

Prolonged erythema can be defined in a number of ways. Erythema is an expected result with the use of most lasers. The duration of erythema is often only 24–72 hours. Prolonged erythema has been reported with all laser and light devices. In general, no treatment is required except reassurance. Non-ablative lasers generally have a shorter duration of erythema, whereas ablative resurfacing lasers have a higher rate of persistent erythema, which can last from weeks to several months.

Hyperpigmentation (Fig. 11.1) is a very common complication and possibly the most common in darker skin types (see the study by Sriprachya-anunt and colleagues). It has been described with the use of almost every laser and light device in darker skin types. In one study by Moreno-Arias and co-workers, it was observed in 16% of patients undergoing IPL treatment. Goh reported that it can be as high as 45% in patients with skin types IV–VI. Wareham et al reported that the pulse dye laser can cause hyperpigmentation, especially on the lower legs and where there is inadequate post-treatment sun protection and sun avoidance. Hyperpigmentation was also seen by Chowdhury and colleagues with the KTP laser. With the ablative CO₂ laser, post-inflammatory hyperpigmentation (PIH) is common and was reported by Badawi et al to occur in 20–30% of Fitzpatrick III and 100% of Fitzpatrick IV patients. Mahmoud et al found the Er : YAG laser to have a PIH rate of 50% in patients with skin type IV–V (Fig. 11.2). Even non-ablative fractional lasers can cause problems with PIH; in a 2010 study by Chan et al there was an 18.2% rate in 47 patients treated. Although rarer, PIH has also been reported (e.g. by Choudhary et al and Kuperman-Beade et al) to occur with the use of Q-switched lasers. In darker skin types, it can be fairly common; it was reported by Lapidoth & Aharonowitz to occur in up to 44% of darker-skinned patients. As noted above, vascular lasers were also found by Clark et al to result in PIH, albeit more rarely.

Figure 11.1 Post-inflammatory hyperpigmentation following treatment with the Q-switched Nd : YAG laser.

Figure 11.2 Post-inflammatory hyperpigmentation following treatment with the erbium : YAG laser.

Hypopigmentation is a less common complication and is most commonly seen with the use of Q-switched lasers for tattoo removal as well as vascular lasers for port-wine stains. Hypopigmentation from Q-switched lasers may be transient, but it can also be permanent. Depigmentation was also reported (by Fitzpatrick & Goldman) to occur with Q-switched lasers. In the treatment of port-wine stains, the pulse dye laser has incidence rates of 2–31% of hypopigmentation. Longer pulse durations with the pulse dye laser seem to lessen the possibility of this complication. The ablative lasers have all been found to cause hypopigmentation (e.g. studies by Trelles and by Ward & Baker). Permanent hypopigmentation has also been described with the use of the CO₂ laser and, in a recent 10-year follow-up study by Prado and colleagues, 8.7% of patients had problems with permanent hypopigmentation.

Reactivation of herpes simplex virus (HSV) is a possible complication for which prophylactic antivirals are often given, especially with resurfacing lasers. However, in a recent retrospective study by Trelles of patients not given antiviral prophylaxis, less than 1% of 600 patients developed reactivation of HSV with the use of a resurfacing laser. In another retrospective study by Campbell & Goldman, only 1.1% of 373 patients developed herpes reactivation with fractionated CO₂ laser resurfacing. Despite a low incidence rate, the potential for scarring with disseminated HSV infection can make this a serious complication.

Acneiform eruptions can occur with any laser and light device and may be due to either procedure or after care. Reported rates depend on the treatment, but in the three studies by Campbell & Goldman, Nanni & Alster, and Neaman et al they ranged from 3 to 15% of patients with resurfacing lasers. This is a relatively benign complication with self-resolution expected.

Scarring has been reported with almost every cutaneous laser and light source (Figs 11.3–11.6). The actual incidence is fairly small, yet overaggressive treatment with any laser or light device can cause it. Hypertrophic scarring is most common with the older continuous wave lasers, most of which are no longer commonly used in office practice.

Figure 11.3 Hypopigmentation and scarring following treatment with the pulsed dye laser.

Figure 11.4 Scarring following treatment with the carbon dioxide laser.

Figure 11.5 Scarring following laser hair removal.

Figure 11.6 Scarring following treatment with an intense pulsed light.

Specific laser complications

The complications covered above are common to almost all laser and light devices. However, there are some specific complications or considerations of various subsets of lasers.