A patient is found to have band-shaped keratopathy on slit-lamp examination — a horizontal, chalky-white opacity across the interpalpebral zone sparing the limbus by a clear peripheral zone. What is the most likely metabolic cause in a patient with longstanding uveitis?
- A Calcium hydroxyapatite deposition in Bowman's layer due to hypercalcaemia or chronic inflammation ✓
- B Deposition of gold salts (chrysiasis) in Bowman's layer
- C Cholesterol crystal deposition (lipid keratopathy) from corneal neovascularisation
- D Iron deposition (siderosis) in the corneal epithelium
Explanation
Band keratopathy is caused by calcium hydroxyapatite deposition in Bowman's layer and superficial stroma, occurring in hypercalcaemic states (hyperparathyroidism, sarcoidosis, vitamin D toxicity) and in chronically inflamed eyes (longstanding uveitis, phthisis bulbi). The clear peripheral zone corresponds to the limbus where CO2 escapes, keeping calcium soluble. Treatment is EDTA chelation (ethylene diamine tetraacetic acid) applied after superficial keratectomy. Gold deposits (chrysiasis) from chrysotherapy produce golden-brown deposits in the corneal stroma, not white band deposits. Lipid keratopathy appears as yellowish-white stromal opacification associated with corneal neovascularisation. Siderosis causes greenish-brown ring (Fleischer ring in keratoconus; Kaiser-Fleischer ring in Wilson's is copper).
Reference: Khurana Comprehensive Ophthalmology, 7th ed.
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Written and medically reviewed by the StethoPrep medical team.