Kayser-Fleischer rings

Last revised by Daniel J Bell on 22 Jul 2021

Kayser-Fleischer rings, sometimes shortened to K-F rings, are caused by copper deposition in the cornea and are a specific, clinical sign of Wilson disease.

They are usually brown or dark reddish in color. Early on they may need a slit lamp to be visible before they become visible to the naked eye. The ring can also be incomplete initially. Kayser-Fleischer rings are present in 95% of Wilson disease cases, including in nearly all cases with neurological manifestations 1,4. The density of the ring correlates well with the activity of the disease 1

The rings are not pathognomonic for Wilson disease.

Kayser-Fleischer rings are caused by direct copper deposition in the Descemet membrane of the cornea and are thought to be from epithelial cells absorbing copper from the aqueous humor 2

Although Wilson disease is the commonest cause of this distinctive ocular appearance, and for many years were believed to be pathognomonic, other causes are recognized 8:

After commencement of copper chelating agents (e.g. penicillamine), the size of the rings usually diminish and may eventually vanish altogether 3.

They were initially described by German ophthalmologist Bernhard Kayser (1869-1954) 7 and German physician Bruno Fleischer (1848-1904) 7 in 1902 and 1903 respectively 5,6.

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