Laser Therapy in Skin of Colour

Skin of colour refers to non-white skin types that usually have a value of V and VI on the Fitzpatrick skin phototypes. It is characterised by an increased amount of epidermal melanin (contains brown pigment), overactive fibroblasts, labile melanocyte response, and more widely distributed melanosomes (granules that contain melanin within melanocytes).

Melanin tends to absorb and scatter energy transmitted from ultraviolet radiation (UVR), which means that skin of colour experiences less epidermal damage after exposure to UVR and has a lower likelihood of undergoing photoaging in comparison with lighter skin types.

Unlike lighter skin, skin of colour almost always develops pigmentary changes as a result of injury and inflammation. Melanin can also act as a competitive chromophore, which increases the risk of developing side effects after epidermal injury caused by laser.

People with darker skin are more susceptible to hypertrophic scarring and keloids following any type of skin injury.

Medical indications for laser therapy are similar across all skin types. However, women of colour frequently receive laser treatment for the reduction of hyperpigmentation related to common aesthetic concerns.

Laser therapy can also be used to remove dark, coarse, and terminal hairs, which often leads to pseudofolliculitis barbae, folliculitis decalvans, and folliculitis keloidalis nuchae in skin of colour.

The safest laser option for people of colour is the long-pulsed infrared laser, such as the Nd:YAG. Its wavelength (1064 nm) is located at the end of the absorption spectrum of melanin, resulting in a sufficient amount of thermal injury to dark and coarse hair. Energy is delivered slowly, which allows for heat dissipation and cooling and minimises damage to the epidermis. However, even infrared lasers may cause hyperpigmentation and other unwanted side effects.

The use of alexandrite laser (755 nm) has not been studied extensively in skin of colour; some cases have reported blistering as a result of its use.

Acne scars are typically treated with ablative CO2 or Er:YAG laser. However, these may cause thermal injury to skin types V and VI and lead to post-inflammatory hyperpigmentation.

Contact cooling can be used to protect the epidermis from thermal injury. This type of cooling relies on conduction and can be active, such as sapphire laser windows and copper tips, or passive, such as ice cubes. Non-contact cooling methods include cold air convection and cryo-cooling.

Several techniques are employed to reduce the likelihood of epidermal injury. The Nd:YAG laser should be used with a long wavelength and wider pulse times. A test pulse or set of pulses can be applied to assess how the skin responds to laser treatment. Multiple short sessions are recommended, as this approach reduces the risk of epidermal damage.

Patient expectations regarding laser treatment should be realistic. Patients should be informed about all potential risks and side effects associated with laser treatment prior to undergoing any procedure.

Newer energy-based devices have a less negative impact on skin of colour and are often preferred. One such device is Infini, a high-intensity focused radiofrequency treatment available at the Centre for Medical and Surgical Dermatology.