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| Optic disc pit ： ウィキペディア英語版 |
Optic disc pit
An optic disc pit is a congenital excavation (or regional depression) of the optic nerve head resulting from a malformation during development of the eye. Optic pits are important because they are associated with posterior vitreous detachments (PVD) and even serous retinal detachments.
== Introduction ==
Optic disc pits were first described in 1882 as dark gray depressions in the optic nerve head. They may, however, appear white or yellowish instead. They can also range greatly in size (e.g. some can be minuscule while others may be large enough as to occupy most of optic disc surface). Optic pits are associated with other abnormalities of the optic nerve including large optic nerve head size, large inferior colobomas of the optic disc, and colobomas of the retina. The optic disc originates from the optic cup when the optic vesicle invaginates and forms an embryonic fissure (or groove). Optic disc pits may develop due to failure of the superior end of the embryonic fissure to close completely.
抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』
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