Optic cup

Opthalmology
The optic cup is the white, cup-like area in the center of the optic disc. The ratio of the size of the optic cup to the optic disc (or cup-to-disc ratio) is measured to diagnose glaucoma.

Embryology
During embryonic development of the eye, the outer wall of the bulb of the optic vesicles becomes thickened and invaginated, and the bulb is thus converted into a cup, the optic cup (or ophthalmic cup), consisting of two strata of cells). These two strata are continuous with each other at the cup margin, which ultimately overlaps the front of the lens and reaches as far forward as the future aperture of the pupil.