WordNet

a continuous portion of a circle
the transparent dome-shaped anterior portion of the outer covering of the eye; it covers the iris and pupil and is continuous with the sclera
a whitish deposit in the shape of an arc that is sometimes seen in the cornea (同)arcus_senilis

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(眼球の)角膜

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出典(authority):フリー百科事典『ウィキペディア（Wikipedia）』「2016/01/27 19:17:52」(JST)

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Arcus senilis (or arcus senilis corneae) is a white, grey, or blue opaque ring in the corneal margin (peripheral corneal opacity), or white ring in front of the periphery of the iris. It is present at birth, but then fades; however, it is quite commonly present in the elderly. It can also appear earlier in life as a result of hypercholesterolemia. Arcus senilis can be confused with the limbus sign, which reflects calcium rather than lipid deposits.

Alternative names

It is also called arcus adiposus, arcus juvenilis (when it occurs in younger individuals), arcus lipoides corneae or arcus cornealis; sometimes a gerontoxon.

Causes

It results from cholesterol deposits in or hyalinosis of the corneal stroma, and may be associated with ocular defects or with familial hyperlipidemia. It is common in the apparently healthy middle aged and elderly; a prospective cohort study of 12,745 Danes followed up for a mean of 22 years found that it had no clinical value as a predictor of cardiovascular disease.^[2]

It can be a sign of disturbance in lipid metabolism, an indicator of conditions such as hypercholesterolemia, hyperlipoproteinemia or hyperlipidemia.

Unilateral arcus is a sign of decreased blood flow to the unaffected eye, due to carotid artery disease or ocular hypotony.

People over the age of 60 may present with a ring-shaped, grayish-white deposit of phospholipid and cholesterol near the peripheral edge of the cornea.

Younger people with the same abnormality at the edge of the cornea would be termed arcus juvenilis.

References

^ Zech Jr, LA; Hoeg, JM (2008). "Correlating corneal arcus with atherosclerosis in familial hypercholesterolemia". Lipids in health and disease 7: 7. doi:10.1186/1476-511X-7-7. PMC 2279133. PMID 18331643.
^ Christoffersen, M; Frikke-Schmidt, R; Schnohr, P; Jensen, GB; Nordestgaard, BG; Tybjærg-Hansen, A (15 September 2011). "Xanthelasmata, arcus corneae, and ischaemic vascular disease and death in general population: prospective cohort study.". BMJ (Clinical research ed.) 343: d5497. doi:10.1136/bmj.d5497. PMC 3174271. PMID 21920887. Retrieved 27 November 2012.

External links

Photo at kumc.edu
Photo at hoppingeyeassociates.com
Photo at apollolipids.org
Definition at Merriam-Webster Medical Dictionary

UpToDate Contents

全文を閲覧するには購読必要です。 To read the full text you will need to subscribe.

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English Journal

Visible aging signs as risk markers for ischemic heart disease: Epidemiology, pathogenesis and clinical implications.

Christoffersen M1, Tybjærg-Hansen A2.
Ageing research reviews.Ageing Res Rev.2016 Jan;25:24-41. doi: 10.1016/j.arr.2015.11.002. Epub 2015 Nov 15.
Association of common aging signs (i.e., male pattern baldness, hair graying, and facial wrinkles) as well as other age-related appearance factors (i.e., arcus corneae, xanthelasmata, and earlobe crease) with increased risk of ischemic heart disease was initially described in anecdotal reports from
PMID 26590331

Association Between Cholesterol Efflux Capacity and Atherosclerotic Cardiovascular Disease in Patients With Familial Hypercholesterolemia.

Ogura M1, Hori M2, Harada-Shiba M2.
Arteriosclerosis, thrombosis, and vascular biology.Arterioscler Thromb Vasc Biol.2016 Jan;36(1):181-8. doi: 10.1161/ATVBAHA.115.306665. Epub 2015 Nov 5.
OBJECTIVE: Patients with familial hypercholesterolemia (FH) are at high risk for premature atherosclerotic cardiovascular disease (ASCVD), especially because of long-term exposure to high low-density lipoprotein cholesterol levels. It has been reported that low-density lipoprotein-lowering therapy d
PMID 26543100

Significance of corneal arcus.

Raj KM1, Reddy PA1, Kumar VC1.
Journal of pharmacy & bioallied sciences.J Pharm Bioallied Sci.2015 Apr;7(Suppl 1):S14-5. doi: 10.4103/0975-7406.155765.
The corneal arcus consists of cholesterol, phospholipids and triglycerides. As serum triglyceride is one of the accurate of lipid metabolic state, greater importance was given, and it was found to be elevated in 72% of patients and a positive correlation with increasing age. This suggests a strong c
PMID 26015693

Related Pictures

★リンクテーブル★

リンク元	「角膜環」「corneal arcus」「角膜輪」
関連記事	「arc」

「角膜環」

Arcus senilis
	Four representative slides of corneal arcus - arcus deposits tend to start at 6 and 12 o'clock and fill in until becoming completely circumferential. There is a thin, clear section separating the arcus from the limbus, known as the lucid interval of Vogt. Image from Zech and Hoeg, 2008.
Classification and external resources
Specialty	ophthalmology
ICD-10	H18.4
ICD-9-CM	371.41
OMIM	107800
DiseasesDB	17120
MeSH	D001112
	[edit on Wikidata]