Optic disc tilt

Degenerative myopia is characterized by disc tilt and myopia arc. As the posterior part of the wall of the highly myopic eyeball bulges backward, the optic nerve enters the ball obliquely. One side of the optic disc (mostly the temporal side) is shifted backward, causing the optic disc to lose its normal slightly elliptical shape under the ophthalmoscope and become a significant vertical (or lateral, oblique) ellipse, even like a dustpan. A crescent-shaped spot is connected to the rearward shift side, which is called a conus, or an extensive conus. The margin of the contralateral disc of the myopic arc is slightly brown, the boundary is blurry, and the ridge-like ridges are upwards. The inner side of the stretched myopia arc is white, which is exposed to the sclera, and the outer side is light brown, which is caused by the disappearance of the pigment epithelium and the choroid exposure. The outer boundary of the myopia arc is clear, but it is often connected with the atrophy of the posterior pole. The myopic arc is located in the temporal side of the optic disc in most cases, and it is also located above or below the temporal disc. More rarely, it is located on the nasal side or the underside. The former is called the inversive conus; the latter is called the Fuchsconus. When the temporal myopia arc extends outward, upward, and downward, it can surround the entire optic disc, which is the circumpapillary chorioretinal atrophy.