Optic disc

Optic disc
Optic disc
Interior of posterior half of bulb of left eye. The veins are darker in appearance than the arteries.
The terminal portion of the optic nerve and its entrance into the eyeball, in horizontal section.
Gray's subject #225 1015
MeSH Optic+Disk

The optic disc or optic nerve head is the location where ganglion cell axons exit the eye to form the optic nerve. There are no light sensitive rods or cones to respond to a light stimulus at this point. This causes a break in the visual field called "the blind spot" or the "physiological blind spot". The optic disc represents the beginning of the optic nerve (second cranial nerve) and is the point where the axons of retinal ganglion cells come together. The optic disc is also the entry point for the major blood vessels that supply the retina.[1] The optic nerve head in a normal human eye carries from 1 to 1.2 million neurons from the eye towards the brain.



The optic disc is placed 3 to 4 mm to the nasal side of the fovea. It is a vertical oval, with average dimensions of 1.76mm horizontally by 1.92mm vertically.[2] There is a central depression, of variable size, called the optic cup.

Clinical examination

The eye is unique because of the transparency of its optical media. Almost all eye structures can be examined with appropriate optical equipment and lenses. Using a modern direct ophthalmoscope gives a view of the optic disc using the principle of reversibility of light. A slit lamp biomicroscopic examination along with an appropriate aspheric focusing lens (+66D, +78D or +90D) is required for a detailed stereoscopic view of the optic disc and structures inside the eye.

A biomicroscopic exam can give an indication of the health of the optic nerve. In particular, the eye care physician notes the colour, cupping size (as a cup-to-disc ratio), sharpness of edge, swelling, hemorrhages, notching in the optic disc and any other unusual anomalies. It is useful for finding evidence corroborating the diagnosis of glaucoma and other optic neuropathies, optic neuritis, anterior ischemic optic neuropathy or papilledema (i.e. optic disc swelling produced by raised intracranial pressure), and optic disc drusen.

Women in advanced stage of pregnancy with pre-eclampsia should be screened by an ophthalmoscopic examination of the optic disc for early evidence of rise in intracranial pressure.

Schematic diagram of the human eye, with the optical disc, or blind spot, at the bottom.

Pale disc

A normal optic disc is orange to pink in colour. A pale disc is an optic disc which varies in colour from a pale pink or orange colour to white. A pale disc is an indication of a disease condition.

Imaging of the optic disc

Traditional colour-film camera images are the gold standard in imaging, requiring an expert ophthalmic photographer, ophthalmic technician, optometrist or an ophthalmologist for taking standardised pictures of the optic disc. Stereoscopic images offer an excellent investigative tool for serial follow-up of suspected changes in the hands of an expert optometrist or ophthalmologist. Automated techniques have also been developed to allow for more efficient and less expensive imaging. Heidelberg Retinal Tomography (HRT-II), GDx-VCC and optical coherence tomography (Stratus-OCT 3) are the currently available computerised techniques for imaging various structures of the eyes, including the optic disc. They quantify the nerve fiber layer of disc and surrounding retina and statistically correlate the findings with a database of previously screened population of normals. They are useful for baseline and serial follow-up to monitor minute changes in optic disc morphology. Imaging will not provide conclusive evidence for clinical diagnosis however, and the evidence needs to be supplanted by serial physiological testing for functional changes. Such tests may include visual field charting, and final clinical interpretation of the complete eye examination by an eye care physician. Ophthalmologists and Optometrists are able to provide this service.

Retinography photograph showing the optic disc as a bright area on the right where blood vessels converge.


  1. ^ blind spot. (2011). In Encyclopædia Britannica. Retrieved from http://www.britannica.com/EBchecked/topic/69390/blind-spot
  2. ^ Duane's Ophthalmology (2006). Ch. 4 Anatomy of the Visual Sensory System

External links

Wikimedia Foundation. 2010.

Look at other dictionaries:

  • optic disc — noun the point where the optic nerve enters the retina; not sensitive to light • Syn: ↑blind spot, ↑optic disk • Hypernyms: ↑point • Part Holonyms: ↑retina * * * optic disc noun …   Useful english dictionary

  • optic disc — optic papilla the start of the optic nerve, where nerve fibres from the rods and cones leave the eyeball. See: blind spot …   The new mediacal dictionary

  • Optic disc — The circular area in the back of the inside of the eye where the optic nerve connects to the retina. Also called the optic nerve head. * * * the start of the optic nerve, where nerve fibres from the rods and cones leave the eyeball. See blind… …   Medical dictionary

  • optic disc — noun The location where ganglion cell axons exit the eye to form the optic nerve …   Wiktionary

  • Optic disc drusen — Classification and external resources ICD 10 H47.3 ICD 9 377.21 …   Wikipedia

  • 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… …   Wikipedia

  • magneto-optic disc — magnetinis optinis diskas statusas T sritis informatika apibrėžtis Didelės talpos daugkartinio rašymo informacijos laikmena, panaši į ↑kompaktinį diską. Duomenys įrašomi įmagnetinant disko paviršių lazeriu. atitikmenys: angl. magneto optic disc;… …   Enciklopedinis kompiuterijos žodynas

  • Диск Зрительного Нерва (Optic Disc), Сосок Зрительного Нерва (Optic Papilla) — начальный участок зрительного нерва, расположенный в том месте, где аксоны ганглиозных клеток сетчатки глаза выходят из глазного яблока. Здесь фоторецепторы отсутствуют. См. Пятно слепое. Источник: Медицинский словарь …   Медицинские термины

  • optic papilla — optic disc …   The new mediacal dictionary

  • Optic neuropathy — Classification and external resources ICD 10 H46 The optic nerve contains axons of nerve cells that emerge from the retina, leave the eye at the optic disc, and go to the visual cortex where input from the eye is processed into vision. There are… …   Wikipedia

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