[Differential diagnosis of corneal dystrophies of the Groenouw I, Reis-Bückler and Thiel-Behnke type].

In the literature there are different definitions of Reis-Bücklers' corneal dystrophy. The corneal disease corresponding to the original description of Reis and Bücklers is interpreted by some authors as an atypical form of granular corneal dystrophy. On the other hand, the honeycomb-shaped corneal dystrophy of Thiel and Behnke is erroneously considered to be Reis-Bücklers' dystrophy. To establish the criteria to make a proper differential diagnosis, we studied the clinical, genetic, histological and electron-microscopical features of the three types of corneal dystrophy in 177 subjects with granular corneal dystrophy, 25 subjects with Reis-Bücklers' dystrophy, and 19 subjects with Thiel-Behnke's dystrophy. Granular corneal dystrophy shows typical corneal opacity patterns, and in our series these were divided into two family-specific variants. Histologically, there are amorphous granules under the epithelium (and possibly throughout the stroma) that consist of electron-dense rod-shaped bodies. The clinical symptoms in Reis-Bücklers' dystrophy (ocular pain in early childhood) differ from those in granular dystrophy. In addition, the corneal opacity pattern (maplike appearance) and the sheetlike arrangement of the deposits in a histological section are different, but the two types of dystrophy are similar with regard to histochemistry and electron microscopy. Thiel-Behnke's corneal dystrophy resembles Reis-Bücklers' dystrophy clinically, but differs from it in its honeycomb-shaped opacity pattern, the fibrous tissue in histology, and the curly dense filaments found in electron microscopy. Correct classification of the three corneal dystrophies is essential for precise diagnosis and may eliminate the present misunderstandings.