Ota nevus, also known as palpebral nevus and Ito nevus, was first reported by Masao Ota in Japan in 1938 as a bluish-brown patchy lesion affecting the sclera and the facial skin innervated by the trigeminal nerve. Nevus of Ota can be inherited autosomal dominantly, but some scholars hold different opinions. Most of the lesions of nevus of Ota are located in the first and second branches of the trigeminal nerve. Nevus of Ota can be divided into light, medium, heavy and bilateral types. 1. Light nevus of Ota (1) Light orbital type: light brown spots, limited to the upper and lower eyelids; (2) Light zygomatic type: light brown spots, limited to the zygomatic bone. 2.Medium-sized nevus of Ota Dark blue to purple-brown, distributed on eyelids, cheekbones and nose root. 3.Heavy nevus of Ota Dark blue to brown, distributed in the area of the first and second branches of the trigeminal nerve. 4.Bilateral nevus of Ota accounts for about 5%. In addition, the following classifications have been proposed in Japan: 1. light type nevus of Ota (also divided into eye socket type, cheekbone type, forehead type and nose type) 2.Medium type nevus of Ota 3.Heavy type nevus of Ota with bilateral distribution is divided into: symmetrical type (also divided into central type and edge type) and asymmetrical type. According to the color, nevus of Ota is divided into: brown type and cyan type. According to the histological characteristics, nevus of Ota is divided into: superficial type (pigment cells are located in the superficial layer of the dermis and are mostly brown in color), deep type (pigment cells are located in the deep layer of the dermis and are mostly cyanotic), and diffuse type (pigment cells are located in the whole layer of the dermis and are mostly purplish-blue in color). According to the age, nevus of Ota is classified as early-onset (within a few years after birth) and late-onset (after puberty).