n.

暗点

WordNet

an isolated area of diminished vision within the visual field
relating to scotoma

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出典(authority):フリー百科事典『ウィキペディア（Wikipedia）』「2012/12/30 05:55:51」(JST)

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A scotoma (Greek for 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

Example of a scintillating scotoma, 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, even when the other eye is closed^{[citation needed]}. The absence of visual imagery from the blind spot does not intrude into consciousness with one eye closed, because the corresponding visual field locations of the optic discs in the two eyes differ^{[citation needed]}.

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

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. 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

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

^ "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. 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
2. 成人における片頭痛の病態生理、臨床症状、および診断 pathophysiology clinical manifestations and diagnosis of migraine in adults
3. 視神経症 optic neuropathies
4. 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
5. 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

English Journal

Optic nerve aspergillosis.

Yuan L1, Prayson RA2.
Journal of clinical neuroscience : official journal of the Neurosurgical Society of Australasia.J Clin Neurosci.2015 Jul;22(7):1191-3. doi: 10.1016/j.jocn.2015.01.012. Epub 2015 Apr 7.
We report a 55-year-old woman with optic nerve Aspergillosis. Aspergillus is an ubiquitous airborne saprophytic fungus. Inhaled Aspergillus conidia are normally eliminated in the immunocompetent host by innate immune mechanisms; however, in immunosuppressed patients, they can cause disease. The woma
PMID 25861888

YAG Laser Membranotomy for Subinternal Limiting Membrane Hemorrhage.

Kim M1, Kim JS, Seo Y, Koh HJ, Lee SC.
Optometry and vision science : official publication of the American Academy of Optometry.Optom Vis Sci.2015 Jul;92(7):e154-7. doi: 10.1097/OPX.0000000000000621.
PURPOSE: To report the use of neodymium:yttrium-aluminum-garnet (Nd:YAG) laser internal limiting membranotomy to successfully treat the first reported case of subinternal limiting membrane (sub-ILM) hemorrhage that developed after coil embolization of a cerebral aneurysm.CASE REPORT: A 59-year-old K
PMID 26002008

Tug of war.

Gospe SM 3rd1, Bhatti MT2, Chavis PS3.
Survey of ophthalmology.Surv Ophthalmol.2015 Jul-Aug;60(4):366-72. doi: 10.1016/j.survophthal.2014.08.006. Epub 2014 Oct 5.
A 74-year-old man had reproducible superior and inferior arcuate visual field defects in the left eye only that were initially believed to be caused by primary open-angle glaucoma. Diagnostic evaluation with the aid of optical coherence tomography revealed extrafoveal vitreomacular traction (VMT) wi
PMID 25891028

Japanese Journal

プリズム法によって偏心視の改善が得られた後期緑内障の1例

江崎秀子
あたらしい眼科 29(8), 1164-1167, 2012-08
NAID 40019415778

Atypical presentation of acute macular neuroretinopathy with tiny parafoveal reddish-brown lesions

MATSUO Yukiko,UEMURA Akinori,NAKANO Tetsuro,INOUE Makoto,SAKAMOTO Taiji
Japanese journal of ophthalmology 55(4), 362-364, 2011-07-01
NAID 10029528107

Related Pictures

★リンクテーブル★

リンク元	「暗点」「ザイデル暗点」「centrocecal scotoma」「cecocentral」「centrocecal」

「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: scotoma, (pl.)scotomata scotomas
関: 盲点、閃輝暗点、中心暗点、弓形暗点、傍中心暗点、盲点中心暗点、輪状暗点

概念

視野内に限局した欠損

種類

「ザイデル暗点」

　　[★]

scotoma
英: Seidel scotoma
同: 盲上暗点 paracentral nuclear scotoma
関: 緑内障、ブエルム暗点、マリオット盲点

「centrocecal scotoma」

　　[★]

盲点中心暗点

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

「cecocentral」

　　[★]

adj.

盲点の

関: blind spot、centrocecal、scotoma

「centrocecal」

　　[★]

adj.

盲点の

関: blind spot、cecocentral、scotoma

[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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scotoma