Coats disease, also known as outer exudative retinopathy, is named after the discoverer of the disease, “Coats G”. Coats disease has a history of more than 100 years since its discovery, and many scientific studies have been conducted by experts and scholars, but the problems, including the pathogenesis, have not been well resolved. Coats disease is a congenital retinal disease due to abnormal blood vessel development. There is some controversy as to whether Coats disease, which develops in children or adolescents and presents with similar vascular changes in adult patients, is also diagnosed. Coats disease occurs overwhelmingly in males and is usually monocular in onset. It is not associated with other systemic abnormalities and is not life-threatening. There is also no evidence of heritability. Coats disease usually has no obvious symptoms such as eye redness or eye pain, and most pediatric patients have no complaints of discomfort. Most patients are seen for visual disturbances, strabismus, or white pupils, and most are discovered by chance by the patient’s parents, teachers, etc. This has led to a significant number of patients being seen in a very serious condition. The diagnosis of Coats requires specialized ophthalmologic examination. There are many diseases, including tumors, that can cause fundus manifestations similar to Coats disease, and great care is needed. The principle of treatment for Coats disease is to destroy the abnormal diseased blood vessels through retinal photocoagulation, retinal condensation, and lazarotomy. The natural prognosis of untreated Coats disease is very poor and may be combined with a variety of complications that may affect the appearance of the eye and facial bone development.