Laboratory Studies
It is prudent to obtain fasting serum lipid levels, as both affected and unaffected members of Schnyder corneal dystrophy pedigrees may have hyperlipidemia and/or hypercholesterolemia.
Other Tests
Confocal microscopy in more advanced stages of Schnyder corneal dystrophy may reveal the absence of corneal nerves.
Genetic testing should reveal mutations in the UBIAD1 gene in affected individuals.
Histologic Findings
Histopathology shows unesterified and esterified cholesterol in basal epithelium; Bowman layer; stroma; and, occasionally, endothelium. Electron microscopy reveals dissolved lipid particles scattered in the subepithelial space throughout the stroma and, rarely, the endothelium. Immunohistochemical analysis has revealed the preferential deposition of apolipoprotein components of HDL. Deposition of cholesterol crystals in patients with Schnyder corneal dystrophy (see the image below) resembles deposition of cholesterol crystals in human atherosclerotic lesions.
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A 22-year-old woman with circular corneal opacity best seen in retroillumination. Weiss JS: Schnyder's dystrophy of the cornea: a Swede-Finn connection. Cornea 1992; 11(2): 93-101.
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A 20-year-old woman with ringlike deposition of anterior stromal cholesterol crystals. Weiss JS: Schnyder's dystrophy of the cornea: a Swede-Finn connection. Cornea 1992; 11(2): 93-101.
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A 37-year-old man with central disclike opacity, affecting the entire stromal thickness, anterior stromal cholesterol crystals, and peripheral arcus lipoides. Weiss JS: Schnyder's dystrophy of the cornea: a Swede-Finn connection. Cornea 1992; 11(2): 93-101.
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A 78-year-old woman with dense arcus lipoides in the corneal periphery, sparing the corneal scleral limbus. Weiss JS: Schnyder's dystrophy of the cornea: a Swede-Finn connection. Cornea 1992; 11(2): 93-101.
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The natural history of Schnyder dystrophy with age. Weiss JS: Schnyder's dystrophy of the cornea: a Swede-Finn connection. Cornea 1992; 11(2): 93-101.