High myopia is defined as nearsightedness of 600 degrees or more. High myopia can cause many complications, common complications are: 1, strabismus, amblyopia, myopic eyes do not need to adjust when looking at the near, so the auxiliary function is correspondingly weakened, prone to exotropia or intermittent exotropia, visual development sensitive period of high myopia is not timely correction, can occur amblyopia; 2, vitreous changes, myopic eyes due to the extension of the eye axis, vitreous cavity expansion, can be secondary to vitreous The vitreous cavity is enlarged due to the lengthening of the eye axis, which can lead to vitreous fluidization, clouding, posterior detachment, and the feeling of floating black shadows or mosquito-like black shadows in front of the eyes, commonly known as flying mosquitoes; 3, retinal changes, due to the lengthening of the eye axis, degenerative changes in the peripheral retina, and the traction of vitreous clouding, etc., which can cause retinal fissures and then retinal detachment; 4, post-scleral staphyloma; 5, macular lesions, such as macular degeneration, macular hemorrhage; 6, glaucoma and Cataract; 7. High myopia has the possibility of inheritance to the next generation.