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arcus se·nil·is -sə-'nil-əs n a whitish ring-shaped or bow-shaped deposit in the cornea that frequently occurs in old age
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a greyish line in the periphery of the cornea, concentric with the edge but separated from it by a clear zone. It begins above and below but may become a continuous ring. It consists of an infiltration of fatty material and is common in the elderly. When it occurs in younger people it may indicate abnormal fat metabolism, but there is great racial variation in its incidence. It never affects vision.
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a. corneae.Medical dictionary. 2011.