Concept: Myopia is a refractive error of more than 600 degrees of myopia, which is called high myopia. Causes: The cause of high myopia is not known. Pathological myopia is more genetically related to the occurrence of myopia. The acquired environment plays an important role in the development of myopia. High myopia should not be used for long-term reading. Hazards: The hazards of high myopia mainly lie in the complications: 1. vitreous lesions: due to the lengthening of the eye axis, the vitreous cavity increases, which leads to progressive degeneration of the vitreous, resulting in successive liquefaction, clouding and posterior detachment. 2, cataract: due to intraocular blood circulation disorders and tissue degeneration and other abnormalities, the lens can also be involved, mainly manifested as clouding of the lens. 3, glaucoma: combined open-angle glaucoma is six to eight times more than normal eyes, and the proportion of normal pressure glaucoma and suspected glaucoma is significantly higher than other people. 4, macular lesion: macular hemorrhage, macular degeneration, macular fissure are common. 5, retinal detachment: It is a common complication of high myopia, with an incidence eight or ten times higher than that of other populations. The proportion of myopic eyes can be as high as 70% or more in primary or foraminogenic retinal detachment. 6, posterior scleral staphyloma: degenerative myopia due to the posterior over-extension of the eye from the equatorial part, the posterior pole sclera is significantly thinner, limited dilatation occurs, under the action of intraocular pressure, the sclera bulges, and the formation of posterior scleral staphyloma of varying sizes. Its occurrence is obviously related to the level of refractive error and the length of the eye. 7.Amblyopia. 8, strabismus. Prevention and treatment: focus on active prevention. Pay attention to the combination of work and rest, avoid overuse of eyesight, intermittent use of liver, kidney and eyesight herbs.