The optic nerve enters the globe obliquely due to the posterior projection of the wall of the highly myopic eye. The side of the optic papilla (mostly temporal) is displaced posteriorly, causing the optic papilla to lose its normal slightly vertical oval shape under the examiner’s eye and become a prominent vertical (or lateral or oblique) oval shape, even like a skip. At the point where it is connected to the posteriorly displaced side, there is a crescent-shaped spot called the myopic arc. The myopic arc is the most common fundus change in myopic eyes. The smallest arcs are not easily visible, while the larger ones can be the size of the optic disc. Some surround the optic disc, and some may reach the macula. If the myopic arc does not invade the macula, it has little effect on visual acuity; if it invades the macula, visual acuity (including near vision) is significantly reduced. Etiology: Elongation of the posterior pole of the eye: One of the reasons for the occurrence of myopic arc is the elongation of the posterior pole of the eye, mainly on the temporal side of the papillae, which can cause the scleral canal of the optic nerve and the optic nerve to both elongate temporally into a deflected cylinder, so that part of the canal wall can be seen by the examining eye. Most obviously, the pure white sclera is exposed, and the choroidal vascular remnants with a small amount of pigmentation can sometimes be seen at the junction with the retina. Choroidal exposure: Another reason for the occurrence of myopic arcs is that in myopic eye elongation, the pigment epithelium of the retina is pulled away from the edge of the papilla, exposing the choroidal vessels that are not masked by the pigment epithelium. The exposed choroid can leave the optic nerve papillae, exposing the sclera behind it, which can also undergo atrophy. The atrophied residual tissue covers the sclera, thus forming curved areas of varying size, yellow and white and residual pigment.