Wilson's Disease: Kayser-Fleischer Ring
Look carefully at the top and bottom edges of the cornea. They have a subtle golden brown or greenish-brown discoloration. An abnormally high serum copper level has led to copper deposition. This sign is present in 97% of patients with neurologic manifestations of Wilson's Disease.
Copper accumulates first at the superior pole, later at the inferior pole, and eventually around the entire corneal circumference. Although it can sometimes be seen with a flashlight, confirmation requires slit lamp examination, often with the aid of a goniolens, which allows a better view of the deep peripheral cornea.
Once neurologic symptoms occur, you can dismiss Wilson's Disease as the cause if there is no K-F ring. Unfortunately, the ring is not nearly as helpful in ruling out Wilson's Disease in patients with purely hepatic manifestations, or in asymptomatic relatives, because it only develops once unbound serum copper levels reach very high levels.
An identical ring can occur in a minority of patients with primary biliary cirrhosis, intrahepatic cholestasis, and partial biliary atresia when these conditions elevate serum copper to levels comparable to those of Wilson's Disease. Hepatocellular disorders can also produce a similar ring when total bilirubin rises acutely above 20.
Other ophthalmic complications
In about 1/5 of patients with neurologically symptomatic Wilson's Disease, there is another ocular sign: the a distinctive multi-colored central opacity with radiating spokes beneath the lens' anterior capsule.
This autosomal recessive disorder is caused by a defect in incorporation of copper in hepatic lysosomes.
Because of faulty storage, copper cannot be excreted in bile, so that it accumulates in liver cells, causing widespread hepatocellular and biliary damage. Once the liver is injured, copper leaches out into the blood stream.
The missteps in the incorporation of copper probably also lead to defective synthesis of a major serum protein carrier of copper: ceruloplasmin. High unbound levels in the serum lead to copper deposits not only in the cornea, but also in the basal ganglia, brainstem, cerebellum, and cerebral cortex, where they cause signal abnormalities on magnetic resonance imaging and devastating neurologic problems.
Ultimately, the diagnosis rests on laboratory studies: high urinary copper, low serum ceruloplasmin, low serum copper (because the low ceruloplasmin causes the bound portion of copper to be low), high liver copper, and low radioactive uptake of copper into liver and ceruloplasmin.
Wilson's Disease is treated with pencillamine, a copper chelator, or zinc or ammonium tetrathiomolybdate. As tissue copper levels fall, the Kayser-Fleischer ring gradually goes away within two years of treatment, but its disappearance does not mirror how effective the treatment is in reversing neurologic manifestations.