Schnyder corneal dystrophy (SCD) is a rare form of stromal corneal dystrophy. It is characterized by clouding of the cornea that results from abnormal deposition of cholesterol and phospholipids. In about 50% of the patients, crystalline cholesterol deposits may be seen in the cornea. Affected persons experience progressive decrease in visual acuity and may have blurring, and/or glare. Bilateral lesions, centrally located, usually appear early in life, however, one eye may become affected before the other. Deposits occur in the anterior stroma near Bowman membrane and reach into deeper layers. Hypercholesterolemia, arcus lipoides and genu valgum have been reported in association with SCD. Diagnosis can be achieved through ophthalmological examination, lipid profile and genetic testing.
Mutations in the UBIAD1 gene causes SCD which is inherited in an autosomal dominant pattern. UBIAD1 gene is located on the short arm of chromosome 1. It consists of 2 exons and spans about 12 kb. This gene encodes a protein believed to be involved in the metabolism of cholesterol and phospholipid.