[Schnyder corneal dystrophy and juvenile, systemic hypercholesteremia].

BACKGROUND: Central crystalline dystrophy of Schnyder is characterized by the deposition of unesterified cholesterol crystals and lipids in the central and paracentral corneal stroma. Classically, this disease has been described as autosomal dominantly inherited and non-progressive with cholesterol deposits found in the anterior one third of the cornea. In recent years, however, rare sporadic cases and individuals with progressive, panstromal Schnyder's dystrophy have been described. Furthermore, an association has been made between some patients with Schnyder's dystrophy and a region on the coast in southwest Finland. Among the stromal dystrophies, this disease is unique with its occasional association with genu valgum and systemic hyperlipidemia. The role of high serum cholesterol in the pathogenesis of this disorder is still unclear. PATIENT: A ten-year-old white male presented with a one year history of ocular irritation made worse by bright sunlight. His past medical history was significant only for attention deficit disorder for which he received methylphenidate. A brother died at four months of age secondary to an unexplained cardiac abnormality. The ocular examinations of the patient's mother and father were normal and no history of eye disease among the grandparents could be elicited. The patient's visual acuity was 20/20 +2 in the right eye and 20/15 -3 in the left eye. The external examination showed no xanthelasmas. Slit-lamp biomicroscopy revealed bilateral ring-shaped corneal opacities extending into the midperiphery but sparing the limbal zone. The ring was composed of a fine, lacy garland of crystals present primarily in the anterior aspect of the stroma just beneath Bowman's membrane. The anterior chamber and iris showed no signs of inflammation. Intraocular pressures were 20 mm Hg and the ocular examination was otherwise unremarkable. Physical exam demonstrated no genu valgum. Blood testing showed a total cholesterol of 201 mg/dl with a low density lipoprotein cholesterol (LDL-C) of 156 mg/dl. Retesting four months later revealed a total cholesterol level of 245 mg/dl and an LDL-C of 192 mg/dl. The patient was referred to the pediatric gastroenterology service where he was put on diet therapy for further management of his hypercholesterolemia.
CONCLUSIONS: This case appears to represent one of the rare sporadic examples of Schnyder's corneal dystrophy. The patient's family history is negative for ocular problems and the parents deny any Scandinavian ancestry. This patient is also unique for his presentation with ocular irritation. Most patients with Schnyder's dystrophy are initially seen for diagnosis of asymptomatic cloudy corneas or for gradual, painless loss of vision although glare in bright sunlight is noted by some individuals. Perhaps the most significant finding concerning this patient are his serum cholesterol levels. The association between total and LDL cholesterol and atherosclerotic vascular disease are well known and the literature suggests that regression of coronary artery disease is possible with aggressive treatment of hypercholesterolemia. Intervention in children should be considered if total cholesterol exceeds 170 mg/dl or LDL-C exceeds 110 mg/dl. Thus, early detection may eliminate significant morbidity and mortality. We therefore advocate evaluating all patients with Schnyder's corneal dystrophy and their immediate family members for systemic hypercholesterolemia.