The cornea is the normally clear ‘windshield’ of the eye. However, a variety of gene mutations cause deposits to appear in this tissue and if these are dense enough, vision becomes dim or blurry. This type of dystrophy (degeneration) is named for a Swiss ophthalmologist, Walter F. Schnyder, who first reported it in 1929.
This disorder has its onset in childhood although the diagnosis is usually not made until the second or third decade of life. Some patients have a cloudiness of the cornea and others may have deposits that look like crystals. By age 40 years almost all patients have evident haziness throughout their corneas. Glare is a common symptom and decreased vision often leads to the need for corneal transplantation in older individuals.
Some individuals have elevated cholesterol and lipids in their blood. Studies suggest that Schnyder corneal dystrophy is due to an abnormality of lipid metabolism in the cornea but evidence for a more generalized disorder in the body is inconclusive.
This is an autosomal dominant condition in which parents often pass on the mutation-causing gene directly to their children in a vertical pattern. If a parent is affected, each child has a 50% chance of inheriting the mutation and of developing the disease.
Haziness of the cornea can be apparent by simple inspection but it takes an eye examination and an experienced ophthalmologist to make the exact diagnosis. Corneal transplantation can restore vision in those in whom it is severely reduced.