1.What does nevus of Ota mean? Nevus of Ota is a common disease among Mongolian people in East Asia, mostly found in women. It was systematically described by Ota, a Japanese doctor, in 1939, hence the name. Most nevus of Ota occurs on one side of the face as brown, greenish-gray to greenish-blue patches or spots, mostly in the area of the first and second branches of the trigeminal nerve, or in severe cases, on both sides of the face and on the sclera. Patients do not have any discomfort, and the nevus does not tend to fade on its own. According to the severity of symptoms and the extent of pigmentation appearing, it is divided into light, medium and heavy, about 50% of pigmentation is congenital, and the rest appears after 10 years old. The distribution of the age of onset shows two peaks, appearing in infancy and adolescence respectively. Occasionally, it appears late or during pregnancy. 2.What causes it? Nevus of Ota occurs mainly because there are too many melanocytes in the dermis of the skin, which may come from local nerve tissue. When the cells are distributed in the superficial layer of the dermis, they are often brown in color, and when they are distributed in the deeper layer of the dermis, they appear as cyan or greenish gray, and the shade of the same color is related to the distribution density of melanocytes. 3.Does it have any effect on health? Apart from affecting the appearance, most of them have no effect on health. However, in a few serious patients, the discolored area will gradually expand and involve the sclera, and the eye pressure will rise and glaucoma will occur. 4.How to treat? The purpose of treatment of this disease is to solve the impact of skin lesions on facial appearance, to achieve cosmetic requirements and to relieve patients’ inner worries. In the past, skin grinding, cryotherapy, dry ice compression method, etc. were used less frequently because of the different degrees of pigment loss and scarring. There is also the use of Chinese herbal medicine in China, but the efficacy has not been verified and patients need to choose carefully. In recent years, the development of laser technology has brought the treatment of nevus of Ota into a new period. Using the principle of selective photothermal action, laser wavelengths are highly selected to act on the absorption peak of melanin to destroy melanocytes without affecting the surrounding normal tissues, thus achieving color fading. The commonly used lasers are Q-switched emerald laser (wavelength 755nm), Q-switched ruby laser (wavelength 694nm), Q-switched Nd:YAG laser (wavelength 1064nm) and Q-switched KTP laser (wavelength 532nm). Since laser treatment can completely remove nevus of Ota, it is advisable to have laser treatment as early as possible, which can relieve the psychosocial pressure of patients and their families. Patients need to pay attention to the following points when receiving laser treatment: 1. Before treatment, facial skin should be carefully cleaned and skin care products and cosmetics should be removed. 2. If patients cannot tolerate the burning sensation during laser treatment, local topical lidocaine cream can be applied and sealed for 1-2 hours before treatment, which can well relieve the pain and discomfort during treatment and increase the comfort during treatment, if younger children cannot tolerate local anesthetic drugs, laser treatment can be performed under intravenous anesthesia. 3. 3, after treatment can be used ice, both to relieve pain, but also to reduce local edema. 4, after treatment local topical antibiotic ointment for a week to prevent infection, and in the treatment area to pay attention to waterproof. 5, after laser treatment need to try to avoid the sun 1-2 months, you can use SPF ≥ 30 sunscreen. 6, after treatment there will be a thin layer of local skin scab, generally need a week to fall off naturally. Do not peel off the scab in advance to avoid superficial scarring.7. The interval between treatments is generally 3-6 months, and a longer interval is beneficial for the body’s phagocytes to fully process the pigment after laser treatment.8. Although the color of nevus of Ota varies from patient to patient, it generally takes 3-6 times or more to obtain complete color removal.9. Do not take aspirin for a period of time before the treatment to avoid increasing the tendency of skin bleeding, and patients with scarring should be treated with caution and can be treated experimentally. In conclusion, suitable laser treatment can be used to completely remove the skin color of patients with nevus of Ota, return patients to a natural and smooth skin, and make patients regain their self-confidence.