I would like to thank Dr Niklas Telinius and his coauthors for their comment on my article “Advantages of anterior segment optical coherence tomography evaluation of Kayser-Fleischer ring in Wilson disease.”1 Dr Telinius and his coauthors have reported the detection of the Kayser–Fleischer (KF) ring using Scheimpflug imaging (Pentacam; Oculus).2 Scheimpflug images of the inferior part of the cornea were analyzed in their series. Because the KF ring appears in the superior cornea first, I was wondering why the superior cornea was not considered for analysis.3 On Scheimpflug images, the KF ring was seen by the authors as a bright subendothelial band peripherally. The authors found that in some cases, the KF ring is visually misdiagnosed because of different levels of brightness of the images. Therefore, the authors normalized the subendothelial signal to epithelial signal. Nine of 11 patients with a KF ring had a normalized signal >1; the 2 patients with a ratio <1 had a faint KF ring on slit-lamp examination. All controls and 9 of 10 patients without a KF ring showed a ratio <1, except 1 patient who, however, had a prominent KF ring superiorly.
My first observation of the KF ring in Wilson disease on anterior segment optical coherence tomography (AS-OCT) (Optovue RTvue premier) was on October 8, 2015. The patient was an 8-year-old female child with liver manifestations of Wilson disease. Since then, I have evaluated 10 patients with KF rings on AS-OCT. In all these patients, the KF ring on the gray scale of AS-OCT was visualized as a hyperreflective band at the level of Descemet membrane in the peripheral cornea. The color scale revealed the KF ring as a greenish/greenish yellow/yellow/yellow orange band. The gray scale was found to measure with relative ease the length of the KF ring, even in children, patients not cooperative for prolonged slit-lamp biomicroscope measurements, and in patients with limbal pigmentation in whom the limits of the KF ring could not be clearly delineated by a slit-lamp biomicroscope.
There are other potential advantages of anterior segment imaging in Wilson disease management, which need to be studied further. Eye care practitioners and imaging experts need to work on a standard method for quantifying the KF ring on anterior segment imaging, which can be used in clinics dealing with patients with Wilson disease. Although the KF ring is said to be diagnostic of Wilson disease, corneal pigment rings have been reported in various other liver diseases and hypercupremia of various causes. KF-like rings occurring in other liver conditions resembled KF rings seen in early or minimal manifestations of Wilson disease.4,5 All these patients were associated with high levels of hepatic copper, serum copper, urinary copper, and serum ceruloplasmin. Pigmented corneal rings in this situation are believed to be due to long-standing cholestasis in which excessive copper deposition occurs in the liver and in other organs due to failure of biliary copper excretion. We need to study all patients with cholestatic liver disease using slit-lamp biomicroscope, anterior segment imaging and also perform genetic analysis for Wilson disease mutations to understand these deposits better. Cases of pigmented corneal rings similar to KF rings have been reported in patients with chronic aggressive hepatitis,4 cryptogenic cirrhosis, and alcoholic patients with cirrhosis with normal levels of serum and liver copper. The deposits in this situation have been called pseudo-KF rings or KF-like rings. These patients had normal or high serum ceruloplasmin levels.