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A depression in the center of the optic nerve through which the blood vessels pass; normal cup to disc ratios range from 0.3 to 0.5 of the disk diameter.
See also: cup
A funnel-shaped depression at or near the centre of the optic disc through which pass the central retinal vessels. Syn. optic cup (although it would be preferable not to use this synonym since this term has another meaning); physiological excavation. See cupped disc; neuroretinal rim.
a depression or hollow.
a depression of the optic disk due to persistently increased intraocular pressure, broader and deeper than a physiological cup, and occurring first at the temporal side of the disk.
an evagination of the optic vesicle, an outgrowth from the neural tube, which forms a cup, the forerunner of the eyeball.
a slight depression sometimes observed in the optic disk.
central depression on the occlusal surface of the horse's incisor teeth at the time of eruption; as the horse ages and the occlusal surface is eroded, the cup becomes smaller and eventually disappears; the reducing size is used in aging of horses by their teeth.