Ultrastructural features of posterior crocodile shagreen of the cornea.

Three elderly patients with a clinical diagnosis of posterior crocodile shagreen of the cornea underwent penetrating keratoplasty. Each of the patients had the characteristic symmetrical, polygonal opacities with indistinct edges and intervening clear spaces in the central posterior corneal stroma. Electron microscopic examination of the keratoplasty specimens disclosed the presence of vacuoles throughout the corneal stroma, many of which contained electron-dense material. The vacuoles were observed with increasing density posteriorly and were most concentrated adjacent to the anterior banded portion of Descemet's membrane. A sawtooth-like configuration of the stromal collagenous lamellae was noted in the posterior cornea in one case. We reviewed the three cases of central corneal clouding reported with histopathological findings as well as the clinical descriptions of this entity. Although a sawtooth-like lamellar configuration of the stromal collagen may be seen by electron microscopy, characteristic vacuoles appear to be the only consistent finding. We believe that posterior crocodile shagreen is most likely a degenerative disorder and that it should be distinguished from central cloudy dystrophy of François by its non-familial pattern of occurrence.