Posterior amorphous corneal dystrophy. An ultrastructural study of a variant with histopathological features of an endothelial dystrophy.
Posterior amorphous corneal dystrophy (PACD) is a rare autosomal-dominant disease, generally classified with the pre-Descemet's dystrophies. It is characterized by deep stromal corneal opacification, flat corneas with low keratometry values, and central thinning. To our knowledge, only one previous ultrastructural study has been published on this disease. This 5-year-old white boy presented with best corrected vision (20/50 right and 20/60 -2 left). The corneas had dense opacities, bilaterally, deep in the corneal stroma. Keratometry was 39.50/40.50, bilaterally. The patient's father had 20/20 vision, bilaterally, with minimal opacifications in the deep corneal stroma. A penetrating keratoplasty was performed. In contrast to the previously reported case of PACD, in which the abnormalities were largely limited to the stroma, our patient had subepithelial deposits, only mild stromal abnormalities, and a thick collagenous layer posterior to Descemet's membrane, thus suggesting that this variant of PACD is a generalized corneal disease including endothelial and epithelial abnormalities, rather than a pure stromal dystrophy.