Schnyder crystalline corneal dystrophy

Schnyder crystalline corneal dystrophy (SCCD) is a rare, genetic eye disorder characterized by the accumulation of cholesterol and phospholipids in the cornea, leading to visual impairment. This condition is typically bilateral, affecting both eyes, and is known for its distinctive appearance of crystal deposits in the cornea. SCCD is classified under the broader category of corneal dystrophies, a group of inherited eye disorders affecting the cornea, the clear, dome-shaped surface that covers the front of the eye.

Etiology and Genetics

SCCD is caused by mutations in the UBIAD1 gene, which is responsible for the biosynthesis of coenzyme Q10 and the regulation of cholesterol and lipid metabolism in the cornea. The condition is inherited in an autosomal dominant manner, meaning that a mutation in just one of the two copies of the gene is sufficient to cause the disorder. Individuals with a family history of SCCD are at an increased risk of developing the condition.

Clinical Features

The hallmark of SCCD is the presence of crystalline deposits in the cornea, which can be observed as early as the first decade of life. However, the severity and progression of the disease vary among individuals. Some affected individuals may remain asymptomatic, while others may experience a range of symptoms, including:

• Decreased visual acuity
• Glare and light sensitivity
• Foreign body sensation in the eye

Over time, the accumulation of crystals can lead to corneal haze and significant visual impairment.

Diagnosis

Diagnosis of SCCD is primarily based on clinical examination, including a detailed eye examination and the observation of crystalline deposits in the cornea. Additional diagnostic tools may include:

• Slit lamp examination
• Corneal topography
• Genetic testing to identify mutations in the UBIAD1 gene

Treatment

There is no cure for SCCD, and treatment is aimed at managing symptoms and preventing progression of the disease. Options may include:

• Lubricating eye drops to alleviate discomfort
• Corneal transplantation in cases of significant visual impairment

Advances in treatment, such as gene therapy, are under investigation and may offer hope for more effective management in the future.

Prognosis

The prognosis for individuals with SCCD varies. While the condition can lead to significant visual impairment, early detection and management can help to preserve vision and improve quality of life.

See Also

• Corneal dystrophy
• Genetic disorders
• Eye diseases