Definition:

Schnyder corneal dystrophy (SCD) is a corneal dystrophy that is characterized by deposition of cholesterol in the corneal stroma. SCD usually becomes apparent early in life with corneal clouding or with crystals within the corneal stroma. Over time, an initially unremarkable corneal stroma acquires small white opacities and a diffuse haze. In approximately 50% of cases, crystals are not evident clinically (Schnyder crystalline dystrophy sine crystals). Most cases of SCD lack an obvious systemic disorder, but hypercholesterolemia is common, and so are associated manifestations, such as arcus lipoides and xanthelasma. An opaque disc of corneal crystals or other lipids may diminish vision sufficiently in both eyes to result in the need for a corneal graft. SCD is caused by one of numerous mutations in the UBIAD1 gene.