Intraocular surgery, most commonly cataract surgery, invariably results in some loss of corneal endothelial cells. In cases of extensive endothelial cell loss, the cornea may decompensate postoperatively, either early in the postoperative period or years later, after more endothelial cells are lost with age. When the endothelium begins to decompensate, Descemet folds and stromal edema occur, followed by intracellular epithelial edema and, ultimately, separation of the epithelium from the Bowman layer. Small separations are referred to as “microcysts”; these may coalesce to form large separations, known as bullae. In more advanced cases of bullous keratopathy, as in Fuchs endothelial dystrophy (discussed later), secondary epithelial basement membrane changes and fibrous pannus may be seen. The Descemet membrane may be thickened, but it typically does not show guttae (Fig 6-15). Although bullous keratopathy is more commonly seen after cataract surgery, in which case it is termed pseudophakic or aphakic bullous keratopathy, it may also be seen after other forms of intraocular surgery, for example, multiple glaucoma procedures or retinal detachment repair with silicone oil (“silicone oil keratopathy”).