Myopic arc

As the posterior part of the wall of the highly myopic eyeball bulges backward, the optic nerve enters the ball obliquely. The side of the optic nipple (mostly the temporal side) is shifted backward, causing the optic nipple to lose its normal slightly vertical ellipse under the ophthalmoscope and become a significant vertical (or horizontal, oblique (oval, even like a dustpan) At the junction with its rearward shifting side, there is a crescent-shaped spot, called a conus, or extensive conus. The myopia arc is the most common fundus change in myopia. The smallest is not easy to see It can reach the size of the optic disc. Some surround the optic disc, even reach the macular area. If the arc of myopia does not invade the macular area, it will have little effect on vision; those who violate the macular will have a significant decrease in vision (including near vision). General In other words, it is difficult to determine whether myopia is still in progress based on the shape of the arc alone. However, according to the fundus observation, if the edge is clear, it can be presumed that myopia has stopped; on the contrary, if the edge is irregular, the extension of the eyeball may still be In progress. When the range of myopia arc is large, especially when the scleral cone or scleral swollen has been formed, due to the tilt of the optic canal, it appears that the optic disc is not perfectly round and becomes a longitudinal ellipse. Due to the optic papilla The temporal part is farther from the cornea than the nasal side, which is also a cause of the tilt of the surface of the optic disc.

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