WordNet

(botany) a tiny outgrowth on the surface of a petal or leaf
a small nipple-shaped protuberance concerned with taste, touch, or smell; "the papillae of the tongue"
a small projection of tissue at the base of a hair or tooth or feather
optical properties; "the optics of a telescope"
the branch of physics that studies the physical properties of light

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乳頭;(毛根・歯根などにある)微小乳頭状突起物
光学
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出典(authority):フリー百科事典『ウィキペディア（Wikipedia）』「2013/10/21 11:53:08」(JST)

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Not to be confused with optical disc.

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.

Anatomy[edit]

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[edit]

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[edit]

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[edit]

Traditional colour-film camera images are the reference 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.

References[edit]

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

External links[edit]

Diagram at Moorfields Eye Hospital
Diagram at Ballard Optical

UpToDate Contents

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1. 視神経の先天性および後天性異常 congenital anomalies and acquired abnormalities of the optic nerve
2. 視神経症 optic neuropathies
3. 非動脈炎性前部虚血性視神経症：臨床的特徴および診断 nonarteritic anterior ischemic optic neuropathy clinical features and diagnosis
4. 非動脈炎性虚血性視神経症：予後および治療 nonarteritic ischemic optic neuropathy prognosis and treatment
5. 視神経膠腫 optic pathway glioma

English Journal

A Visual Pathway for Looming-Evoked Escape in Larval Zebrafish.

Temizer I1, Donovan JC2, Baier H3, Semmelhack JL1.
Current biology : CB.Curr Biol.2015 Jun 24. pii: S0960-9822(15)00667-3. doi: 10.1016/j.cub.2015.06.002. [Epub ahead of print]
Avoiding the strike of an approaching predator requires rapid visual detection of a looming object, followed by a directed escape maneuver. While looming-sensitive neurons have been discovered in various animal species, the relative importance of stimulus features that are extracted by the visual
PMID 26119746

Choroidal Thickness Decreased in Acute Primary Angle Closure Attacks with Elevated Intraocular Pressure.

Song W1, Huang P, Dong X, Li X, Zhang C.
Current eye research.Curr Eye Res.2015 Jun 16:1-6. [Epub ahead of print]
PURPOSE: To study the choroidal thickness (CT) changes in patients having unilateral acute primary angle closure (APAC) attacks with elevated intraocular pressure (IOP).METHODS: This study included 23 patients with unilateral APAC attacked eyes. The CT at macular and peripapillary regions were measu
PMID 26079201

Retinal nerve fiber layer thickness analysis in cases of papilledema using optical coherence tomography - A case control study.

Ahuja S1, Anand D2, Dutta TK3, Roopesh Kumar VR4, Kar SS5.
Clinical neurology and neurosurgery.Clin Neurol Neurosurg.2015 Jun 9;136:95-99. doi: 10.1016/j.clineuro.2015.05.002. [Epub ahead of print]
BACKGROUND: Papilledema is defined as an optic disk swelling that is secondary to elevated intracranial pressure. Early diagnosis of papilledema can help in early intervention thus preventing visual loss and even death. Optical coherence tomography (OCT) is a non-invasive imaging technique which can
PMID 26093225

Japanese Journal

初期の臨床症状として視覚障害を呈した神経セロイドリポフスチン症のチワワの1例

日本獣医師会雑誌 67(11), 862-865, 2014
NAID 130004888053

カニクイザルのデジタル眼底写真による「緑内障性視神経乳頭・網膜神経線維層変化判定ガイドライン」を用いた緑内障の判定

比較眼科研究 32(0), 29-33, 2013
NAID 130005061463

臨床講座(26)緑内障

Pharma tribune 3(2), 19-30, 2011-02
NAID 40018725788

Related Pictures

★リンクテーブル★

リンク元	「optic nerve head」
関連記事	「opt」「optic」「optics」「papilla」

「optic nerve head」

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.
Latin	Discus nervi optici
Gray's	subject #225 1015
MeSH	Optic+Disk