High myopia usually refers to myopia of 600 degrees or more. Myopia can be divided into three stages depending on the degree: 1. mild myopia, usually within 300 degrees. 2. moderate myopia refers to myopia between 325 and 600 degrees. 3. more than 600 degrees is called high myopia. High myopia has a great impact on the eyes, and in addition to the loss of distance vision, various pathological changes can occur, such as early vitreous clouding, liquefaction, flying mosquitoes in front of the eyes, floaters, and flash sensation. The fundus examination can also reveal obvious highly myopic fundus lesions, such as optic disc atrophy arc and retinal pigment disorder. In addition, macular cleavage, macular hemorrhage, retinal fissure, and even retinal detachment can occur in severe cases, so for highly myopic patients it is recommended to make sure to have regular fundus examinations.