Bullous keratopathy is a state of abnormal corneal epithelial hydration characterized clinically by corneal opacification and the presence of epithelial vacuoles and bullae. In its advanced form, a pannus develops. The stroma becomes vascularized and scarred and, finally, calcium may be deposited in the anterior portions of the stroma. There are probably many factors governing corneal turgescence, and their mechanism is complex. One of the most important factors controlling corneal hydration, and therefore corneal transparency, is the integrity of the corneal endothelium. When this layer is sufficiently damaged, the cornea becomes edematous, and if this edema persists for a sufficient length of time bullous keratopathy develops. The first changes seen in the pathogenesis of bullous keratopathy are in the endothelium. The cells of this layer, which are normally low and rectangular in shape, become flattened and attenuated. Later, their concentration is reduced and finally they may disappear. Figure 1 is