Granular corneal dystrophy is diagnosed during an eye examination by an ophthalmologist or an optometrist.

Granular corneal dystrophy has two types:

Granular corneal dystrophy is a slowly progressive corneal dystrophy that most often begins in early childhood.

Granular corneal dystrophy is caused by a mutation in the TGFBI gene, located on chromosome 5q31.

Granular corneal dystrophy type I , also corneal dystrophy Groenouw type I, is a rare form of human corneal dystrophy.

In Granular corneal dystrophy multiple small white discrete irregular spots that resemble bread crumbs or snowflakes become apparent beneath Bowman zone in the superficial central corneal stroma.

Mutations in TGFB1 which encodes transforming growth factor beta cause several forms of corneal dystrophies including granular corneal dystrophy, lattice corneal dystrophy, epithelial basement membrane dystrophy, Reis-Bucklers corneal dystrophy, and Thiel-Behnke dystrophy.