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Corneal Dystrophies – Keratoplasty

Corneal dystrophies comprise a group of hereditary and acquired disorders of unknown cause, characterized by deposits in the layers of the cornea and alteration of the corneal structure. Corneal dystrophies are associated with all five layers of the cornea. Although the disease usually originates in the inner layers (Descemet’s membrane, the stroma, and Bowman’s membrane), the degeneration, erosion, and deposits affect all layers.

Corneal endothelium constantly removes fluids from the cornea to maintain its clarity. As the endothelial cells are gradually lost, the dystrophy progresses. Once lost, the endothelial cells do not grow back but instead spread out to fill the empty spaces. The pump system becomes less efficient, causing corneal clouding, swelling, and eventually reduced vision.

MANAGEMENT

The goal of treatment is to restore visual clarity for both safety and improved quality of life.

MEDICAL MANAGEMENT

Dystrophies cannot be cured; however, with certain medications, blurred vision resulting from corneal swelling can be controlled. Saline eyedrops or ointments are often prescribed to draw fluid from the cornea and reduce swelling. Another simple technique that reduces moisture in the cornea is to hold a hair dryer at arm’s length, blowing air into the face with the eyes closed. This technique draws moisture from the cornea, temporarily decreases swelling, and improves vision.

SURGICAL MANAGEMENT

Corneal Transplantation

Corneal transplantation (keratoplasty) is the use of donor corneas to improve the clarity of vision. Two depths of keratoplasty are performed. Penetrating keratoplasty indicates full-thickness corneal replacement; lamellar keratoplasty denotes a partial-thickness procedure.
Clipboard01 Keratoplasty

Because there is a direct relationship between age and health of the endothelial layer of the cornea, young donor tissue is preferred. Donor eyes are obtained from cadavers; donor eyes must be enucleated soon after death because of rapid endothelial cell death and must be stored in a preserving solution.

Corneal transplantation surgery is usually performed with the client under local anesthesia. Unlike cataract surgery, however, visual return after a corneal transplant is relatively slow and typically takes 6 to 12 months. The reason for the slow return of vision is that the sutures holding the new cornea in place tend to distort the vision, and they must be left in place for a considerable time before it is safe to remove them.

Rejection of donor tissue can occur following corneal transplantation from unsuitable storage of donor tissue, dystrophy of the donor’s endothelium, surgical trauma, or immunologic rejection. Wound leakage, bleeding into the anterior chamber, glaucoma, cataract, and infection are other complications that may occur. At the first sign of graft rejection, when the cornea becomes cloudy and edematous and when there is an anterior chamber reaction (the presence of white blood cells or protein), topical steroids are prescribed in frequent doses to control the inflammatory response and to reverse the rejection reaction. In severe cases, a second transplantation may be necessary.

NURSING MANAGEMENT

PRE – OP

    • Explaining to the patient what is expected out of procedure.
    • Informed consent.
    • Sometimes topical anesthetic is given before surgery, the eye can be protected by an eye pad or glasses.

POST – OP

  • Corneal transplantation is usually performed as outpatient surgery.
  • Postoperatively the client returns from the operating room with an eye patch and protective shield in place. Observe the patch for signs of drainage.
  • The client should experience only mild to moderate discomfort, which should be relieved by acetaminophen. Unreduced pain may indicate a rise in IOP and should be reported to the surgeon.
  • Because the eye patch is to be in place until the following morning, assess the client’s ability for self-care and reinforce information on the hazards of monocular vision.
  • The eye is examined the next morning with the slit lamp. Depending on the extent of preoperative visual limitations, most clients experience improved vision immediately.
  • Instruct clients, however, not to overestimate their expectations for full vision. Vision continues to improve gradually because the healing process may take up to a year or more.
  • Glasses or contact lenses are usually needed to obtain the best result. Many months may be required for restoration of vision, and revisions in the care plan may be needed.

SELF-CARE

Postoperative eyedrops usually include an antibiotic and a corticosteroid. Topical corticosteroid therapy may be needed indefinitely. Discharge instructions include the rationale for the medications and proper instillation technique.

It is important for the client to wear eye protection in the form of regular glasses, sunglasses, or a protective shield to prevent injury to the eye. Advise the client never to rub the eye. The area around the eye may be cleaned with warm tap water using a clean washcloth.

Teach the client and family to recognize the clinical manifestations of increased IOP, infection, and graft rejection. A mnemonic tool may be useful in teaching the client to remember the signs of graft rejection (RSVP):

  • R Redness
  • S Swelling
  • V Decreased vision
  • P Pain

Advise the client to evaluate vision in the eye each day. A picture on the wall or some object in a well-lighted room should be selected as a point of reference. If a change in vision from the day before is noted, the client should re-evaluate his or her vision in a few hours. If no improvement is noted or if vision is worse, the client should notify the physician. Because graft rejection may occur at any time (even years) after the surgery, advise the client to make the vision check a routine part of ADL for the rest of his or her life.