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Bullous keratopathy is a condition in which the cornea becomes permanently swollen. This occurs because the inner layer of the cornea, the endothelium, has been damaged and is not pumping fluid properly (Figure 1). The cause of the endothelial damage could be from trauma, glaucoma, or inflammation after eye surgery. Endothelial keratoplasty (EK) is the recommended treatment for bullous keratopathy.
Certain intraocular lens implant designs can damage the cornea. Sometimes it is helpful to replace a lens implant with a newer design when a transplant is being performed to prevent damage to the transplant.
The causes of bullous keratopathy have changed over the last two decades. Twenty years ago, the most common reason for bullous keratopathy was complications from cataract surgery with or without problems from intra-ocular lenses. Over the past 20 years, cataract surgery techniques and intra-ocular lens implants have improved dramatically. Now, corneal problems are less common after cataract surgery. Currently, one of the most common reasons for developing bullous keratopathy, or secondary corneal decompensation, is from problems related to glaucoma surgery.
Glaucoma surgery can lead to corneal failure because of direct damage to the cornea either during surgery or in the immediate post-operative period. Often this is from the cornea coming into contact with the other structures in the eye like the iris or lens. Another association between glaucoma and bullous keratopathy is that sometimes the cornea can decompensate after a laser treatment is performed to treat acute angle closure glaucoma. In acute angle closure glaucoma, the iris blocks the normal flow of eye fluid from the area where it is produced behind the iris to the trabecular meshwork in front of the iris, where the fluid drains from the eye. The treatment for acute angle closure glaucoma is to make a hole in the peripheral iris so the fluid can bypass the areas of blockage. Typically if a drainage hole is made in the iris before acute angle closure happens, it does not cause corneal problems. However, when the drainage hole (called an iridotomy) has to be made after the eye is inflamed from the onset of acute angle closure, there can be secondary decompensation of the cornea either immediately or even years later. This is particularly a problem in Asian eyes, where the space between the iris and cornea is often smaller. Being farsighted (hyperopia) can be a risk factor for this type of glaucoma.