Definition: Bullous keratopathy is a swelling of the cornea
Incidence/Prevalence: Bullous keratopathy is most common in older people. Bullous keratopathy occurs after cataract surgery, its incidence has decreased since the advent of intraoperative viscoelastic agents that protect the corneal endothelium and the decreased use of iris plane and anterior chamber intraocular lenses. A review at the University of Toronto indicate that pseudophakic bullous keratopathy is the 3rd leading indication of pentrating keratoplasty. (
Maeno et al.) No gender proclivity is documented.
Etiology: Often the cause of bullous keratopathy is loss of endothelium from a malpositioned intraocular lens. There is failure of the corneal endothelial cell layer to perform its normal pump function. The pumping failure can occur either because the cells themselves do not function normally or because the absolute number of endothelial cells has decreased below a critical level necessary to maintain corneal clarity.
Clinical Presentation: Bullous keratopathy occurs most commonly after cataract removal. Bullous keratopathy is characterized by the formation of fluid-filled blisters on the surface of the cornea. (
Click here to link to a clinical photograph). The blisters rupture, causing pain, often with a foreign body sensation and impairment of vision.. The diagnosis is made from the typical appearance of a swollen, cloudy cornea with blisters on the surface. Pachymetry will confirm a thicker cornea.
Histopathology: The epithelium is seen desquamating from the surface (1) or completely separating from Bowman's layer creating the bullous detachment (2). There are hydropic changes (tiny bubbles) within the epithelium giving them less apparent staining (3). Bowman's layer is irregularly thinned probably related to the bullae (4). The stroma shows areas devoid of keratocyte nuclei and irregular lamellae (5), features indicative of scarring. The endothelium is markedly attenuated; there are fewer endothelial cells than normally. Here we find only a single endothelial cell in this view (6). Additional findings that may be seen include a thickened and redundant epithelial basement membrane. There is a paucity of endothelial cells, and those cells remaining are flattened and attenuated. Descemet’s membrane is preserved intact.
Treatment:
Bullous keratopathy is treated by reducing the amount of fluid in the cornea. Hypertonic drops can be used to draw the fluid out. Occasionally, soft contact lenses can be used to decrease discomfort. If vision is insufficient for daily activities or discomfort is significant, corneal transplantation is indicated.
