eMedicine Specialties > Ophthalmology > Cornea

Keratopathy, Pseudophakic Bullous: Treatment & Medication

Author: James V Aquavella, MD, Professor of Ophthalmology, Department of Ophthalmology, University of Rochester School of Medicine, University of Rochester Eye Institute
Coauthor(s): Zoe R Williams, MD, Staff Physician, Department of Ophthalmology, University of Rochester School of Medicine, Strong Memorial Hospital; Gregory J McCormick, MD, Consulting Staff, Corneal and Refractive Surgery, Vermont Laser Vision at Timber Lane and Ophthalmic Consultants of Vermont; Diane E Singer, MD, Clinical Senior Instructor, Department of Ophthalmology, University of Rochester Medical Center
Contributor Information and Disclosures

Updated: Feb 19, 2008

Treatment

Medical Care

Therapy for PBK and ABK is performed to reduce discomfort or to increase visual acuity. The corneal edema associated with bullous keratopathy is chronic and usually noninflammatory. A number of treatment options are available.

• The reduction of intraocular pressure is an important treatment for corneal edema, because increased intraocular pressure can compromise endothelial function and lead to epithelial edema and further endothelial damage. Topical antiglaucomatous medications can help to reduce pressure and can give the endothelium the best chance to deturgesce the cornea. Epinephrine derivatives should be avoided because of the risk of cystoid macular edema.
• Epithelial edema often can be managed with topical hypertonic agents such as sodium chloride (5%) ointment or drops. In a study to evaluate efficacy, visual acuity was used as the only parameter to monitor therapeutic efficacy. While 61% of eyes had improved visual acuity on the medication, this group included patients with other causes for corneal edema. One third of patients with bullous keratopathy had improvement in visual acuity. Improvement was demonstrated following use of the medication for 3 months.
• Hydrophilic contact lenses, on an extended-wear basis, can be used to decrease pain associated with epithelial bullae. While these lenses do not reduce the amount of edema, they can improve visual acuity to the extent that they mask surface irregularity.  
  • Hydrophilic extended-wear contact lenses used in association with 5% hypertonic saline can be used as a hypertonic reservoir to constantly bathe the cornea, and, in some cases, they can improve visual acuity by decreasing epithelial and stromal edema. In this way, a lens plus hypertonic saline can compensate for an environment in which surface dehydration to help maintain deturgescence is defective.
  • Pain associated with bullous keratopathy can be due to rupture of the bullae with exposure of corneal nerve endings or swelling of the epithelium, leading to the stretching of nerve endings.
  • As mentioned earlier, pain associated with bullous keratopathy can be due to rupture of bullae with exposure of corneal nerve endings. Extended-wear hydrophilic bandage lenses can alleviate pain as long as the lens remains in place. It is thought that the lens acts as an effective precorneal protective layer and shields the abnormal epithelium from the environment, preventing bullae from bursting. The lens does not prevent the formation of bullae, but perhaps when new bullae do occur, the corneal nerve endings are not exposed to drying and other noxious stimuli because the lens covers them. Fitting of the lens is an important consideration. Lenses that have excessive movement can further irritate the epithelium and be uncomfortable. Lenses that are too tight can act as a suction cup and result in inflammation and even anterior uveitis (tight lens syndrome). Furthermore, a greater risk of corneal infection may exist when a bandage contact lens is used in an eye with corneal edema.
• In the presence of low-grade inflammation, topical steroids can be useful, since low-grade anterior uveitis, not infrequently, is associated with chronic corneal edema.

Surgical Care

Surgical treatments for bullous keratopathy include enucleation or evisceration, retrobulbar alcohol injection, conjunctival flap, cauterization of the Bowman layer, anterior stromal micropuncture, excimer laser phototherapeutic keratectomy (PTK), annular keratotomy, penetrating keratoplasty, and Descemet stripping automated endothelial keratoplasty (DSAEK).

• A conjunctival flap is an excellent procedure to decrease pain in eyes with painful bullous keratopathy. A Gunderson-type flap undermines the superior bulbar conjunctiva and moves in and down to cover the cornea with intact "bridges" nasally and temporally. Amniotic membrane has been used successfully to cover swollen corneas and to decrease pain. Neither of these procedures is designed to improve the vision.
• Cauterization of the Bowman layer is performed for pain relief. This procedure is thought to produce a dense fibrous barrier between the corneal stroma and the epithelium so that fluid cannot permeate into the epithelial cells and produce bullous changes. Anterior stromal micropuncture and excimer laser PTK also have been used with some success to cause scarring of the superficial cornea and to decrease pain.
• Annular keratotomy has been used to treat the pain associated with bullous keratopathy in eyes with poor visual potential. A partial-thickness corneal incision is made with a trephine and relieves pain by severing branches of corneal ciliary nerves to decrease corneal sensation.
• Penetrating keratoplasty and, more recently, DSAEK, in which the diseased corneal endothelium is replaced with healthy donor endothelium, are the only surgical treatments that can relieve pain and restore visual acuity. DSAEK has been shown to have several advantages over traditional penetrating keratoplasty, including faster visual recovery time and more predictable refractive outcome.¹ Importantly, because DSAEK is based on selective component corneal transplantation, it potentially enables a single donor cornea to be used in the treatment of multiple patients whose pathology involves different corneal layers.  
  • Visual acuity in an eye with bullous keratopathy also may be affected by cystoid macular edema. In one study, cystoid macular edema was related to poor vision in 62% of those with visual acuity of less than 20/40 and in 36% of all patients treated with penetrating keratoplasty for PBK.
  • Cystoid macular edema is thought to result from excessively traumatic intraocular surgery. In patients with PBK, the intraocular lens may be removed or exchanged at the time of transplant. Displaced lenses causing recurrent uveitis, closed loop, or anterior chamber iris supported lenses generally should be removed. Patients undergoing penetrating keratoplasty with and without intraocular lens removal or exchange fared similarly as far as visual acuity was concerned. Therefore, no adverse effect of retaining a securely fixated intraocular lens was present.
  • Exchange for 1-piece anterior chamber intraocular lenses gives significantly better visual acuity than exchange for sutured posterior chamber intraocular lenses. When the original intraocular lens is retained, graft failure rate for posterior chamber intraocular lenses is less than that for anterior chamber and iris supported lenses.
  • A prospective study of 27 patients with PBK who underwent penetrating keratoplasty, intraocular lens explantation, and secondary Verisyse intraocular lens implantation demonstrated less endothelial cell loss 1 year postoperatively with retropupillary enclavation of the intraocular lens as compared with intraocular lens enclavation in the anterior chamber.² The study found that the increased anterior chamber depth enabled by the posterior technique was correlated with greater endothelial cell preservation.²  
• Improved surgical techniques of cataract extraction have resulted in a reduction in the number of bullous keratopathy cases; however, bullous keratopathy still continues to be a major indication for penetrating keratoplasty. Penetrating keratoplasty techniques also have improved, but cystoid macular edema associated with previous intraocular surgery may limit improvement in visual acuity. The decision to proceed with penetrating keratoplasty must be made after weighing the risks of infection, secondary glaucoma, and graft rejection; however, penetrating keratoplasty remains the treatment most likely to markedly improve visual acuity.

Medication

The goal of medical treatment is to improve visual acuity by deturgescence of the edematous corneal epithelium.

Hypertonic agents

Hypertonic saline solution dehydrates the epithelium and tends to improve acuity.

5% Sodium chloride (Muro 128, Adsorbonac, SalineX, Ak-NaCl)

Dehydrates the cornea.

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