Granular Corneal Dystrophy Type I

Type I granular corneal dystrophy (GCDI) is a rare form of stromal corneal dystrophy (see this term) characterized by multiple small deposits in the superficial central corneal stroma, and progressive visual impairment, which may sometimes be severe.

Epidemiology

Prevalence of this form of corneal dystrophy is not known. GCDI appears to be more prevalent in Europe than in other regions.

Clinical description

Lesions appear within the first decade of life and may be evident by 3 years of age. Early symptoms include glare and photophobia that usually start before the end of the first decade of life. Visual acuity decreases as opacification progresses with age. Recurrent erosions are seen frequently. Homozygotes have more severe manifestations.

Etiology

GCDI is caused by a p. Arg555Trp mutation in the multifunctional TGFBI gene (5q31).

Diagnostic methods

Lesions resemble white, discrete, irregularly-shaped, sharply-demarcated spots in the stroma.

Differential diagnosis

The appearance of the granular deposits in GCDI differs from those in GCDII and unlike GCDII, amyloid deposits do not occur. The features of GCD may be very similar to the corneal features of monoclonal gammopathies (see these terms).

Genetic counseling

Both forms of GCD usually follow an autosomal dominant pattern of inheritance, but sporadic de novo mutations have been reported.

Management and treatment

When indicated, a penetrating keratoplasty is the ideal form of therapy.