[Pseudokeratoconus in trisomy 21 and posterior polymorphous corneal dystrophy].

The authors examined three members of a family with an autosomal dominant trait of posterior polymorphous corneal dystrophy of varying expressivity. The 67-year-old white mother had a visual acuity of 20/30, with only discrete irregularities at the level of Descemet's membrane. The daughter developed bullous keratopathy with polymorphous ring-shaped opacities in the central area of Descemet's membrane early, in her 34th year. The 25-year-old son, who also had Down's syndrome, presented with the clinical symptoms of acute keratoconus. Light microscopy revealed a thickened, multilaminated Descemet's membrane with vesicles, breaks, and dislocation of endothelial cells into the deep stroma. Transmission electron microscopy showed a normal anterior, ribbonlike portion of Descemet's membrane and a fibroblastic differentiation of the corneal endothelial cells.