With the changing demographics in many parts of the world, an increasing proportion of patients who seek aesthetic services have come from a diverse ethnic background. Ethnic skin typically falls within Fitzpatrick's skin phototypes III–VI. These dark-skinned patients vary considerably in their response to sunlight, sun exposure, photodamage, and photoaging compared to the Caucasians. Therefore, it is important to be aware of the special needs of these patients with ethnic skin, and to select the most appropriate lasers and light sources in the treatment of congenital or acquired pigmentary conditions.
The cutaneous applications of lasers and light sources in dark-skinned patients differ from their use in Caucasians in several aspects. Firstly, ethnic skin tends to have more congenital and acquired pigmentary disorders. Conditions like nevus of Ota and Hori's nevus are more commonly seen in skin of color. Secondly, darker skin has larger melanocytes which produce more melanin. The melanosomes are distributed individually in keratinocytes, hence conferring significant photoprotection compared to fair skin. Aging in ethnic skin manifests 10 to 20 years later than age-matched Caucasian counterparts. Furthermore, the early signs of photoaging in dark-skinned patients commonly consist of pigmentary changes, like solar lentigines, freckles, seborrhoeic keratosis, and dermatosis papulosa nigra, rather than wrinkling as seen in Caucasians. Thirdly, the higher epidermal melanin content in ethnic skin together with the broad absorption spectrum of melanin on the electromagnetic spectrum create significant technical challenges in the use of cutaneous lasers and light sources on dark-skinned patients. The highly melanized epidermis of ethnic skin can absorb and interfere with the absorption of laser energy which is intended for another target, such as pigment within the hair follicle, a blood vessel or tattoo ink within the dermis. Hence, special considerations must be given for the selection of treatment parameters for ethnic skin in order to optimize results and to minimize unwanted side effects, such as post-inflammatory hyperpigmentation (PIH). This chapter aims to discuss the effective and safe use of lasers and light sources in the management of pigmentary conditions seen in ethnic skin. The treatment of melasma will be covered in another Chapter 15.
CLINICAL EXAMINATION AND PATIENT HISTORY
When assessing any pigmentary condition, it is paramount to make a correct clinical diagnosis before initiating treatment with lasers and light sources. For certain benign pigmented lesions, like melasma, assessment with Wood's light can help in assessing the epidermal and dermal components.
In the preoperative consultation, the patient's chief complaint, concerns and treatment expectations are addressed. These aspects should be interpreted in light of the patient's cultural background. A detailed medical history is necessary to assess for any contraindications to laser and light treatment. The use of oral retinoids within the past 6 months can increase the risk of scarring from laser treatment. Furthermore, any active infection or recent sun exposure of the treatment area, tendency for keloid and scar formation, photosensitivity, ...