WordNet

in or near a center or constituting a center; the inner area; "a central position"
a workplace that serves as a telecommunications facility where lines from telephones can be connected together to permit communication (同)telephone exchange, exchange
an isolated area of diminished vision within the visual field

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『中心の』,中央の,中心からの / 『主要な』,中心的な(main) / (音声が)中舌音の / 電話交換局(《英》[telephone]exchange)

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出典(authority):フリー百科事典『ウィキペディア（Wikipedia）』「2014/01/24 07:40:53」(JST)

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A scotoma (Greek σκότος/skótos, darkness; plural: scotomas or scotomata) is an area of partial alteration in the field of vision consisting of a partially diminished or entirely degenerated visual acuity that is surrounded by a field of normal – or relatively well-preserved – vision.

Example image showing normal field of vision

Example image showing a peripheral ring scotoma, as may be caused by retinitis pigmentosa

A depiction of a scintillating scotoma that was almost spiral-shaped, with distortion of shapes but otherwise melting into the background similarly to the physiological blind spot, as may be caused by cortical spreading depression

Every normal mammalian eye has a scotoma in its field of vision, usually termed its blind spot. This is a location with no photoreceptor cells, where the retinal ganglion cell axons that comprise the optic nerve exit the retina. This location is called the optic disc. When both eyes are open, visual signals that are absent in the blind spot of one eye are provided from the opposite visual cortex for the other eye. The absence of visual imagery from the blind spot does not intrude into consciousness because the corresponding visual field locations of the optic discs in the two eyes differ.

The presence of the scotoma can be demonstrated subjectively by covering one eye, carefully holding fixation with the open eye, and placing an object (such as one's thumb) in the lateral and horizontal visual field, about 15 degrees from fixation (see the blind spot article). The size of the monocular scotoma is 5×7 degrees of visual angle.

Scotoma is also a symptom of retinal damage from exposure to high-powered lasers.

The term scotoma is also used metaphorically in psychology to refer to an individual's inability to perceive personality traits in themselves that are obvious to others.

Presentation of pathological scotoma[edit]

Symptom-producing, or pathological, scotomata may be due to a wide range of disease processes, affecting either the retina (in particular its most sensitive portion, the macula) or the optic nerve itself.^{[contradictory]} A pathological scotoma may involve any part of the visual field and may be of any shape or size. A scotoma may include and enlarge the normal blind spot. Even a small scotoma that happens to affect central or macular vision will produce a severe visual handicap, whereas a large scotoma in the more peripheral part of a visual field may go unnoticed by the bearer because of the normal reduced optical resolution in the peripheral visual field.

Causes[edit]

Common causes of scotomata include demyelinating disease such as multiple sclerosis (retrobulbar neuritis), damage to nerve fiber layer in the retina (seen as cotton wool spots) due to hypertension, toxic substances such as methyl alcohol, ethambutol and quinine, nutritional deficiencies, and vascular blockages either in the retina or in the optic nerve. Scintillating scotoma is a common visual aura in migraine.^[1] Less common, but important because they are sometimes reversible or curable by surgery, are scotomata due to tumors such as those arising from the pituitary gland, which may compress the optic nerve or interfere with its blood supply.

Rarely, scotomata are bilateral. One important variety of bilateral scotoma may occur when a pituitary tumour begins to compress the optic chiasm (as distinct from a single optic nerve) and produces a bitemporal paracentral scotoma, and later, when the tumor enlarges, the scotomas extend out to the periphery to cause the characteristic bitemporal hemianopsia. This type of visual-field defect tends to be obvious to the person experiencing it but often evades early objective diagnosis, as it is more difficult to detect by cursory clinical examination than the classical or textbook bitemporal peripheral hemianopia and may even elude sophisticated electronic modes of visual-field assessment.

In a pregnant woman, scotomata can present as a symptom of severe preeclampsia, a form of pregnancy-induced hypertension. Similarly, scotomata may develop as a result of the increased intracranial pressure that occurs in malignant hypertension.

References[edit]

^ "Possible Roles of Vertebrate Neuroglia in Potassium Dynamics, Spreading depression, and migraine", Gardner-Medwin, J. Exp. Biology (1981), 95, pages 111-127 (Figure 4).

UpToDate Contents

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1. 急性持続性視力喪失が認められた成人に対するアプローチ approach to the adult with acute persistent visual loss
2. 一過性黒内障（一過性単眼または両眼視力低下） amaurosis fugax transient monocular or binocular visual loss
3. 視神経症 optic neuropathies
4. 視神経炎：病態生理、臨床的特徴、および診断 optic neuritis pathophysiology clinical features and diagnosis
5. 小児における中枢神経系の急性脱髄の鑑別診断 differential diagnosis of acute central nervous system demyelination in children

English Journal

Validity of the temporal-to-nasal macular ganglion cell-inner plexiform layer thickness ratio as a diagnostic parameter in early glaucoma.

Park JW1, Jung HH1, Heo H1, Park SW1,2.
Acta ophthalmologica.Acta Ophthalmol.2015 Aug;93(5):e356-65. doi: 10.1111/aos.12666. Epub 2015 Jan 25.
PURPOSE: To evaluate the diagnostic validity of temporal-to-nasal macular ganglion cell-inner plexiform layer thickness (TNM) ratio using Cirrus high definition-optical coherence tomography (HD-OCT) in patients with early glaucomatous damage.METHODS: Enrolled participants included 130 normal control
PMID 25619801

The scotogenic contact lens: a novel device for treating binocular diplopia.

Robert MP1, Bonci F2, Pandit A2, Ferguson V3, Nachev P4.
The British journal of ophthalmology.Br J Ophthalmol.2015 Aug;99(8):1022-4. doi: 10.1136/bjophthalmol-2014-305985. Epub 2015 Feb 13.
Binocular diplopia is a debilitating visual symptom requiring immediate intervention for symptomatic control, whether or not definitive treatment is eventually possible. Where prismatic correction is infeasible, the current standard is occlusion, either by a patch or an opaque contact lens. In elimi
PMID 25680615

Biotinidase deficiency mimicking neuromyelitis optica: Initially exhibiting symptoms in adulthood.

Bottin L1, Prud'hon S1, Guey S1, Giannesini C1, Wolf B2, Pindolia K2, Stankoff B3.
Multiple sclerosis (Houndmills, Basingstoke, England).Mult Scler.2015 Jul 22. pii: 1352458515596457. [Epub ahead of print]
BACKGROUND: Children with untreated biotinidase deficiency can experience variable symptoms depending on their age of presentation. Older children and adolescents can exhibit predominant neurological deficits including para- or tetraparesis and vision loss.METHODS: We report the first case of delaye
PMID 26203071

Japanese Journal

視神経乳頭炎を呈した神経ボレリア症の1例

臨床神経学 55(4), 248-253, 2015
NAID 130005066231

血漿浄化療法が著効したNMO spectrum disorderの1男性例：症例報告および血漿浄化療法開始のtherapeutic time windowに関する文献的考察

神経眼科 31(4), 470-475, 2014
NAID 130005057118

ロービジョンと表情認知の基礎的研究:－顔認知に及ぼす顔サイズと網膜偏心度の効果－

日本視能訓練士協会誌 43(0), 47-53, 2014
NAID 130004822904

Related Pictures

★リンクテーブル★

リンク元	「中心暗点」「centrocecal scotoma」
関連記事	「central」

「中心暗点」

Scotoma
	Classification and external resources
	; Example image showing small, deep central scotoma, as may be caused by age-related maculopathy
ICD-10	H53.4, H53.1
ICD-9	368.4, 368.12
MeSH	D012607

　　[★]

英: central scotoma
ラ: scotoma centrale
関: 暗点、閃輝暗点、弓形暗点、傍中心暗点、盲点中心暗点、輪状暗点

概念

視野の中心部(中心固視点)を含む暗点。

原因

網膜脈絡膜疾患：中心性漿液性網脈絡膜症、黄斑変性、黄斑円孔
視神経疾患：視神経炎、球後視神経炎、視神経症

特徴

網膜脈絡膜疾患：実性暗点：暗点を自覚する
視神経疾患：虚性暗点：暗点を自覚しない

国試

104G054：網膜動脈分枝閉塞症により黄斑領域に虚血病変を来して、眼底検査上ではcherry red spotが、また視野検査では中心暗点が見られる。

「centrocecal scotoma」

　　[★]

盲点中心暗点

関: arcuate scotoma、central scotoma、paracentral scotoma、ring scotoma、scintillating scotoma、scotoma

「central」

　　[★]

adj.

中心の、中心的な、中心性の、中枢的な、中枢性の、中枢の、中枢神経性の

関: center、centrally、centrally acting、centre、centro、centrum、hub、medial、pivotal、pivotally

[1] "Possible Roles of Vertebrate Neuroglia in Potassium Dynamics, Spreading depression, and migraine", Gardner-Medwin, J. Exp. Biology (1981), 95, pages 111-127 (Figure 4).

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案内

案内

central scotoma