Myopia is a common disease in ophthalmology, from the classification of myopia, 400 degrees of myopia belongs to moderate myopia, this situation will cause the elongation of the eye axis, so if the eye appears 400 degrees of myopia, about the equivalent of the eye length than normal to exceed about 2mm, in this case the eye will definitely appear a significant decline in vision. After this situation, you should go to a regular hospital for an early optometry examination to accurately understand the degree of myopia and wear frame glasses early to improve corrective vision. Of course, in addition to frame glasses, you can also choose corneal contact lenses, which can be directly attached to the corneal surface to correct myopia more effectively. For adults, there are also surgical options, such as excimer laser surgery and femtosecond laser surgery.