Kayser-Fleischer ring

Overview
Kayser-Fleischer rings are dark rings that appear to encircle the iris of the eye. Synonyms include Gowers' chorea, hepatolenticular degeneration, or Westphal-Struempell pseudosclerosis.

Differential Diagnosis
Ceruloplasmin deficiency (synonyms include Ferroxidase deficiency, Aceruloplasminemia, Caeruloplasmin deficiency)

Eye
The rings, which consist of copper deposits where the cornea meets the sclera, in Descemet's membrane, first appear as a crescent at the top of the cornea. Eventually, a second crescent forms below, at 6 o'clock, and ultimately completely encircles the cornea.

In later stages, the brownish rings can be seen with the naked eye. In earlier stages, an optometrist's or ophthalmologist's slit lamp reveals the golden brown or greenish-yellow crescents.

Associations
Kayser-Fleischer rings are a sign of Wilson's disease, which involves abnormal copper handling by the liver resulting in copper accumulation in the body and is characterised by cerebral degenerative changes, liver cirrhosis, splenomegaly, involuntary movements, muscle rigidity, psychic disturbances, and dysphagia.

Kayser-Fleischer rings also appear in cases of chronic copper poisoning, as sometimes happens when children are fed milk warmed in copper or brass pots or when drinking water contains high levels of dissolved copper.

Chronic copper poisoning causes symptoms similar to Wilson's disease, including anemia and liver and kidney damage.

Symptoms of acute copper toxicity include nausea, vomiting, and diarrhea and can result in anemia, severe liver damage and death.