The integrity of the endothelium of the cornea is essential in maintaining normal corneal hydration. In addition to the high resistance to the flow of water across the endothelium,1 there is evidence for endothelial cell function which actively transports fluid from the stroma to the anterior chamber to maintain deturgescence.2 The specific nature of this mechanism has not been definitely demonstrated.
Bullous keratopathy or epithelial edema results from a breakdown of the normal dehydrating mechanism of the cornea. It is usually encountered in glaucoma with high tension and Fuch's dystrophy in the later stages. In these instances the epithelial edema is more generalized and present centrally. Localized damage to the epithelium may cause bullous keratopathy. Bacterial and fungal infections, herpes simplex keratitis, and recurrent erosions are frequently implicated. The edema is in the vicinity of the pathology and usually does not persist after healing is complete. Bullous keratopathy
LAIBSON PR. Inferior Bullous Keratopathy and Unsuspected Anterior Chamber Foreign Body. Arch Ophthalmol. 1965;74(2):191-197. doi:10.1001/archopht.1965.00970040193012