Bullous Keratopathy

Bullous keratopathy is caused by edema of the cornea, resulting from failure of the corneal endothelium to maintain the normally transparent, dehydrated state of the cornea. Most frequently, it is due to Fuchs corneal endothelial dystrophy or corneal endothelial trauma.

Fuchs dystrophy is a genetic disorder that causes bilateral, progressive corneal endothelial cell loss, sometimes leading to symptomatic bullous keratopathy by age 50 to 60. Fuchs dystrophy may be autosomal dominant with incomplete penetrance.

Corneal endothelial trauma can occur during intraocular surgery (eg, cataract removal) or after placement of a poorly designed or malpositioned intraocular lens implant. Bullous keratopathy after cataract removal is called pseudophakic (if an intraocular lens implant is present) or aphakic (if no intraocular lens implant is present) bullous keratopathy.

Subepithelial fluid-filled bullae form on the corneal surface as the corneal stroma (the deeper dense connective tissue layer of the cornea) swells, leading to decreased visual acuity, loss of contrast, glare, and photophobia. Sometimes bullae rupture, causing pain and foreign body sensation. Bacteria can invade a ruptured bulla, leading to a corneal ulcer Corneal Ulcer A corneal ulcer is a corneal epithelial defect with underlying inflammation usually due to invasion by bacteria, fungi, viruses, or Acanthamoeba. It can be initiated by mechanical trauma... read more .

Slit-lamp examination of all types of bullous keratopathy reveals corneal epithelial bullae and swelling of the corneal stroma. Fuchs dystrophy also demonstrates multiple minute excrescences (guttata) on the endothelial surface and/or thickening of Descemet's membrane, giving a “beaten metal” appearance to the back surface of the cornea. All the symptoms and findings are characteristically worse when patients first wake up and improve throughout the day. This is because moisture accumulates—and edema worsens—when the eyes are closed during sleep and progressively dries by evaporation when the eyes are open.

Also required for diagnosis of all types of bullous keratopathy is increased corneal thickness as measured by ultrasonic pachymetry.

Treatment by an ophthalmologist is required and includes topical dehydrating agents (eg, hypertonic [5%] sodium chloride drops and ointment), intraocular pressure–lowering agents, occasional short-term use of therapeutic soft contact lenses for some mild to moderate cases, and treatment of any secondary microbial infection. When these treatments are inadequate to restore functional vision, corneal transplantation Corneal Transplantation Corneal transplantations are done for several reasons: To reconstruct the cornea (eg, replacing a perforated cornea) To relieve intractable pain (eg, severe foreign body sensation due to recurrent... read more is usually curative.