Bullous Keratopathy is the most common reason for a penetrating keratoplasty. Edema of the epithelial cells followed by subepithelial bullae is seen. Intraepithelial cysts can occur as fragments of basement membrane can deposit within the epithelium. In aphakic or pseudophakic bullous keratopathy, the surgical trauma decreases the number of endothelial cells and the cornea stroma cannot rid itself of excess fluid and becomes edematous and cloudy. Back to Cornea