Ota nevus, also known as oculo-palatal brownish nevus, was systematically described by a Japanese physician, Ota, in 1939, hence the name. Clinical characteristics 1. Ota nevus occurs mostly in yellow and black people. The incidence rate is 0.15%-0.8%, and it is rare among Caucasians. The disease is mostly seen in females, with a male to female ratio of about 1:5.6. The age of onset shows two peaks, appearing in infancy and adolescence respectively, with the most frequent occurrence within one year of age, accounting for 61.35%, followed by 11-20 years of age, accounting for about 20%; it is rare after 20 years of age. There is no family history of the disease, and the genetic relationship is not significant. The pathological change of this disease is the proliferation of melanocytes in the dermis, which belongs to the dermal pigment proliferation skin disease. (1) Skin damage: The lesions of nevus of Ota are usually located on the face and the area innervated by the I and II branches of the trigeminal nerve. The basic damage is patchy, sometimes mildly elevated, with no hair on it and unclear borders, and the color varies from brown, greenish gray to cyan and purple-brown. The initial sites of lesions are: lower lid, zygomatic, sclera, temporal, and upper lid, in that order. (2) Mucous membrane involvement: Nevus of Ota can widely involve the mucous membranes of the eyes, ears, nose, mouth, throat and other parts. Ocular pigmentation is the most common. (3) Complications: Glaucoma is the most common ocular complication of nevus of Ota. In addition, other dermal pigment cell hyperplasia skin diseases (Mongolian spots, blue nevus, Ito nevus, etc.) are often associated with it. 3. Clinical efficacy (1) Treatment review Before the introduction of short pulse laser, the main treatment means include chemical peeling, grinding, implantation, freezing, continuous laser, etc. (2) Current treatment Ruby laser, emerald gem laser, Nd:YAG laser. These lasers are applied for 3-4 times with an interval of 3-6 months each. Clinical efficacy is good. Rarely recurrence occurs.