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Optic cup
Wiggle stereogram showing the optic cup in a healthy eye
Details
Identifiers
Latin	excavatio disci
TA98	A15.2.04.020
TA2	6789
FMA	77664
Anatomical terminology[edit on Wikidata]

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 (cup-to-disc ratio, or C/D) is one measure used in the diagnosis of glaucoma. Different C/Ds can be measured horizontally or vertically in the same patient. C/Ds vary widely in healthy individuals. However, larger vertical C/Ds, or C/Ds which are very different between the eyes, may raise suspicion of glaucoma. A C/D which enlarges vertically over months or years suggests glaucoma.

Cup-to-disc ratio

The cup-to-disc ratio (often notated CDR) is a measurement used in ophthalmology and optometry to assess the progression of glaucoma. The optic disc is the anatomical location of the eye's "blind spot", the area where the optic nerve leave and blood vessels enter the retina. The optic disc can be flat or it can have a certain amount of normal cupping. But glaucoma, which is in most cases associated with an increase in intraocular pressure, often produces additional pathological cupping of the optic disc. The pink rim of disc contains nerve fibers. The white cup is a pit with no nerve fibers. As glaucoma advances, the cup enlarges until it occupies most of the disc area.

The cup-to-disc ratio compares the diameter of the cup portion of the optic disc with the total diameter of the optic disc. A good analogy to better understand the cup-to-disc ratio is the ratio of a donut hole to a donut. The hole represents the cup and the surrounding area the disc. If the cup fills 1/10 of the disc, the ratio will be 0.1. If it fills 7/10 of the disc, the ratio is 0.7. The normal cup-to-disc ratio is less than 0.5. A large cup-to-disc ratio may imply glaucoma or other pathology. However, cupping by itself is not indicative of glaucoma. Rather, it is an increase in cupping as the patient ages that is an indicator for glaucoma. Deep but stable cupping can occur due to hereditary factors without glaucoma.

References

1. Algazi VR, Keltner JL, Johnson CA (December 1985). "Computer analysis of the optic cup in glaucoma". Investigative Ophthalmology & Visual Science. 26 (12): 1759–70. PMID 4066212.
2. "Glaucoma causes Optic Nerve Cupping (atrophy) and Vision Loss". The Eye Digest. The University of Illinois Eye and Ear Infirmary. Archived from the original on 8 July 2012.
3. "Eye Exam and tests for Glaucoma diagnosis". The Eye Digest. The University of Illinois Eye and Ear Infirmary. Archived from the original on 8 July 2012.

v t e Anatomy of the globe of the human eye
Fibrous tunic (outer)	Sclera Episcleral layer Schlemm's canal Trabecular meshwork Cornea Limbus layers Epithelium Bowman's Stroma Dua's layer Descemet's Endothelium
Uvea / vascular tunic (middle)	Choroid Capillary lamina of choroid Bruch's membrane Sattler's layer Ciliary body Ciliary processes Ciliary muscle Pars plicata Pars plana Iris Stroma Pupil Iris dilator muscle Iris sphincter muscle
Retina (inner)	Layers Inner limiting membrane Nerve fiber layer Ganglion cell layer Inner plexiform layer Inner nuclear layer Outer plexiform layer Outer nuclear layer External limiting membrane Layer of rods and cones Retinal pigment epithelium Cells Photoreceptor cells (Cone cell, Rod cell) → (Horizontal cell) → Bipolar cell → (Amacrine cell) → Retina ganglion cell (Midget cell, Parasol cell, Bistratified cell, Giant retina ganglion cells, Photosensitive ganglion cell) → Diencephalon: P cell, M cell, K cell, Muller glia Other Macula Perifoveal area Parafoveal area Fovea Foveal avascular zone Foveola Optic disc Optic cup Ora serrata
Anatomical regions of the eye	Anterior segment Adnexa (Eyebrow, Eyelid, Conjunctiva, Lacrimal system, Orbit) Fibrous tunic Anterior chamber Aqueous humour Iris Posterior chamber Ciliary body Lens Capsule of lens Zonule of Zinn Posterior segment Vitreous chamber Vitreous body Retina Choroid
Other	Keratocytes Ocular immune system Optical coherence tomography Eye care professional Eye disease Refractive error Accommodation Physiological Optics Visual perception

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