When the eye is adjusted at rest, equal light from 5 meters away passes through the refraction of the eye, the focal point falls exactly on the retina and can form a clear image, and the eye with this refractive state is called orthokeratology. An eye whose focal point falls in front of the retina and cannot accurately form a clear image on the retina is called axial myopic. However, it is highly adaptive to scattered light from near targets, and can obtain clear vision as long as the target moves a certain distance toward the eye. Therefore, myopic eyes see near targets clearly and see far blurred, which can be corrected with concave spherical lenses. Clinical manifestations: 1. decreased distance vision, normal near vision; 2. visual fatigue; 3. exotropia or co-rotation exotropia may occur, and the strabismic eye is mostly the one with high myopia; 4. high myopia often has vitreous liquefaction and clouding, and is complicated by cataracts and consciousness of black shadows floating in front of the eyes or vision loss; 5. low and moderate eye fundus generally have no changes or leopard-like fundus, myopic solitary spots, high myopia optic nerve papillae In high myopia, the optic nerve papilla is slightly protruding due to the long axis of the eye, accompanied by a deeper anterior chamber and larger pupil, and a slight retardation to light reversal; 7, the use of concave spherical lens can improve visual acuity. The diagnosis is based on 1. Decreased distance vision and normal near vision. 2.Concave spherical lens correction to improve visual acuity. 3.High myopia fundus examination can clarify the diagnosis, such as high myopia often appears vitreous liquefaction, degeneration, clouding. 4.It may be accompanied by co-rotation exotropia.