This is an anterior corneal dystrophy involving the epithelium and Bowman membrane. Opacities consisting of spots and lines form in the central portion of the anterior cornea creating haziness with relative sparring of the periphery. These can be seen as early as 4-5 years of age but few symptoms occur until the epithelium breaks down causing painful corneal erosions. Visual acuity eventually drops as the corneal haze increases along with increasing irregularity of the epithelial surface.
Ultrastructural studies reveal degenerative changes in all epithelial cells and almost complete Bowman membrane replacement with disoriented collagen fibrils.
A comparative histological study of Reis-Bucklers and Thiel-Behnke dystrophies concluded that these are distinct CDB (corneal dystrophy Bowman) disorders and suggested the former be called CDB type I, and the latter CDB type II. Type II is considered unique on the basis of the ‘curly’ fibers seen in the Bowman and subepithelial layers, while type I has bandshaped granular Masson-positive subepithelial deposits and ‘rod-shaped bodies’ resembling granular dystrophy. Type I described here generally leads to greater vision loss than type II.