The limbus sign is a ring of dystrophic calcification evident as a "milky precipitate" (i.e. abnormal white color) at the corneal limbus.
The corneal limbus is the part of the eye where the cornea (front/center) meets the sclera (white part of the eye).
Thought to be caused by increased calcium concentration in the blood, this sign however persists after calcium phosphate concentration returns to normal.
[1] Compare the limbus sign (calcification) with arcus senilis (lipid).
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