ptosis

ptosis

[toh-sis]
noun Pathology.
1.
a drooping of the upper eyelid.
2.
prolapse or drooping of any organ.

Origin:
1735–45; < Neo-Latin < Greek ptṓsis a falling

ptotic [toh-tik] , adjective
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World English Dictionary
ptosis (ˈtəʊsɪs)
 
n , pl ptoses
prolapse or drooping of a part, esp the eyelid
 
[C18: from Greek: a falling]
 
ptotic
 
adj

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American Heritage
Medical Dictionary

ptosis pto·sis (tō'sĭs)
n. pl. pto·ses (-sēz)
Abnormal lowering or drooping of an organ or a part, especially a drooping of the upper eyelid caused by muscle weakness or paralysis.

The American Heritage® Stedman's Medical Dictionary
Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.
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Encyclopedia Britannica
Encyclopedia

ptosis

drooping of the upper eyelid. The condition may be congenital or acquired and can cause significant obscuration of vision. In congenital ptosis the muscle that elevates the lid, called the levator palpebrae superioris, is usually absent or imperfectly developed. If severe and not corrected in a timely manner, congenital ptosis can lead to amblyopia and permanent vision loss. Congenital palsy of the third (oculomotor) cranial nerve (which normally stimulates elevation of the upper lid) is a more rare cause of congenital ptosis.

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Encyclopedia Britannica, 2008. Encyclopedia Britannica Online.
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