Acute corneal edema in pellucid marginal degeneration or acute marginal keratoconus.

: This article reports a case of bilateral corneal pellucid marginal degeneration. The right cornea had an acute hydrops. Both eyes underwent penetrating keratoplasty. A histopathological study of the corneal specimens was performed by light and electron microscopy. The histological changes observed on the right cornea showed breaks on Bowman's layer, edema and disorganization of the stromal collagen, and break of Descemet's membrane. The ultrastructural changes were similar to those observed in acute keratoconus, leading to the belief that these two corneal diseases are closely related.