Ocular Pathology

Anatomy and pathology of the human eye. Use it to review eye pathology for Ophthalmology Board Review or OKAP.

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Tuesday, February 06, 2007

Band Keratopathy

Calcific Band Keratopathy
Definition: Dystrophic calcification of Bowman’s layer or superficial anterior cornea that forms a distinctive calcified band across the central cornea.
Incidence/Prevalence: Exact incidence of calcific band keratopathy is unknown.
Etiology: Band keratopathy derives its name from the distinctive appearance of calcium deposition in a band across the central cornea. Band keratopathy can occur from a variety of causes, both systemic and local. Bank keratopathy is associated with chronic corneal edema (perhaps the most common treatable cause accounting for over 1/4 of cases in one series), phthisis bulbi, chronic iridocyclitis, severe glaucoma, hyperparathyroidism, vitamin D excess, sarcoidosis or renal disease. The latter 4 are related to abnormal calcium metabolism. Severe dry eye may also precede band keratopathy. Herpes keratitis may predispose to band keratopathy. The use of phosphate salts in steroid preparations may precipitate calcium in patients with epithelial defects.
Clinical Findings: Seen clinically as calcific plaques in the interpalpebral zone, band keratopathy is characterized by the deposition of calcium in the epithelial basement membrane, Bowman’s layer, and anterior stroma. There is usually an intervening region of cornea between the limbus and the calcification that is unaffected. In the macroimage of the cornea one can see the unaffected cornea (number and arrow 1), the band of calcification spanning arrows labeled 2 and incidental arcus senilis (yellow number 3).
Histopathology: In early cases there is a stippled basophilia of Bowman’s layer (number 1 in the figures) in H&E sections. As the disorder progresses, the calcium deposits merge to form a linear array along Bowman’s layer. In the figure arrow 2 shows the linear array forming. The deposits may spill over into the anterior stroma (arrow 3).
Special stains can be used to document that the substance is calcium. The von Kossa stain reacts to give a black color.

Treatment: Generally, the cornea epithelium is abraded physically or chemically. 19% ethanol can be used to gently remove the epithelium and rolled to the side. The calcium is rubbed off, often with a sponge soaked in a solution of ethylenediamine-tetraacetic acid (EDTA). The epithelium is replaced and a bandage contact lens is worn temporarily. Excimer laser has been used effectively but may cause a myopic shift.

Najjar DM et al.

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