Patient Information

Related Images

Click on images to enlarge
Corneal crystals in Schnyder corneal dystrophy
Central corneal crystals
Central corneal crystals in Schnyder corneal dystrophy
Central corneal crystals
Retroillumination of corneal crystals in Schnyder corneal dystrophy
Retroillumination of corneal crystals
Retroillumination of corneal crystals in Schnyder corneal crystals
Retroillumination of corneal crystals

Corneal Dystrophy, Schnyder

Clinical Characteristics

Ocular Features

Schnyder corneal dystrophy has its onset early in life as a haziness of the central cornea with some peripheral extension.  The stroma gradually becomes more hazy and eventually in about 50% of patients yellow-white crystalline deposits can be seen in an annular pattern in the Bowman layer and the adjacent stroma just beneath. The remaining layers of the cornea are not involved.  The needle-shaped crystals are often birefringent and composed of cholesterol and phospholipids. There is considerable variation in the progression of disease and in the symmetry of disease in the two eyes.  Visual acuity may be relatively good in young people but older patients with denser central opacification eventually require corneal transplantation for better vision.

Systemic Features

Some patients have hypercholesterolemia and hyperlipidemia.  Skin fibroblast cultures in one patient have shown cytoplasmic deposits consistent with unesterified cholesterol but another study failed to find such deposits in skin or conjunctiva.  Evidence points to a metabolic disorder of lipid metabolism in the cornea but the evidence for a more generalized systemic disorder is inconclusive.  Genu valgum has been reported in some patients.

Genetics

Schnyder crystalline dystrophy of the cornea results from a mutation in the UBIAD1 gene located on chromosome 1 (1p36.3).  Multiple mutations have been identified.  It is inherited in an autosomal dominant pattern.

Treatment Options

Penetrating keratoplasty can be helpful in restoring vision but the corneal deposits and opacification often recurs.  PTK procedures can also be beneficial.

References

Weiss JS. Schnyder corneal dystrophy. Curr Opin Ophthalmol. 2009 Jul;20(4):292-8. Review.

PubMed ID: 
19398911

Weiss JS, Kruth HS, Kuivaniemi H, Tromp G, Karkera J, Mahurkar S, Lisch W, Dupps WJ Jr, White PS, Winters RS, Kim C, Rapuano CJ, Sutphin J, Reidy J, Hu FR, Lu da W, Ebenezer N, Nickerson ML. Genetic analysis of 14 families with Schnyder crystalline corneal dystrophy reveals clues to UBIAD1 protein function. Am J Med Genet A. 2008 Feb 1;146(3):271-83. (Note: Erratum: Am. J. Med. Genet. 146A: 952-964, 2008.)

PubMed ID: 
18176953

Dinh R, Rapuano CJ, Cohen EJ, Laibson PR. Recurrence of corneal dystrophy after excimer laser phototherapeutic keratectomy. Ophthalmology. 1999 Aug;106(8):1490-7.

PubMed ID: 
10442892