Surgical Approach to Corneal Disease

There are many options for surgical intervention to treat the large spectrum of corneal disease. If the pathology is limited to the superficial 50–75 μm of the cornea, phototherapeutic keratectomy (PTK) may be the best choice. For corneal scarring or disease confined to the anterior one-third of the cornea, superficial anterior lamellar keratoplasty (SALK) is an excellent option. In patients who have more extensive stromal disease but a healthy endothelium, such as with keratoconus, postinfectious keratitis, and corneal dystrophy or scarring, DALK is increasingly popular. In cases of primary endothelial dysfunction such as Fuchs corneal dystrophy, pseudophakic bullous keratopathy (PBK), or corneal graft failure, EK has become the procedure of choice. However, penetrating or fullthickness corneal transplantation (PK) is a viable alternative for any type of corneal pathology and is particularly useful in patients with combined epithelial, stromal, and endothelial disease or with graft failure and high astigmatism. A comparison of these procedures appears in Table 15-3. In the subset of patients with severe ocular surface disease or multiple graft failures, a keratoprosthesis may provide the best prognosis for vision rehabilitation.

Table 15-3

The discussion of corneal transplantation in this chapter is intended to provide a basic understanding of surgical techniques involved with the procedures and is not meant to be comprehensive. Many excellent resources are available for this purpose; they are listed in the references. Although most ophthalmologists do not perform corneal transplantation, all should be familiar with preoperative evaluation for appropriate referral of patients and postoperative management should problems arise.

Preoperative Evaluation and Preparation

A complete eye examination is necessary prior to corneal transplantation; the examination should include a detailed social history to help determine whether the patient will adhere to the postoperative regimen and report promptly if problems arise. Simple clinical tests, such as those for color recognition or an afferent pupillary defect, can be very important in evaluating patients with media opacity. Ocular surface problems such as dry eye, trichiasis, exposure, blepharitis, and rosacea must be recognized and treated before transplantation. In older patients, the increased risk of problems with anesthesia and the rare complication of expulsive hemorrhage must also be considered. In addition, the postoperative course may be more problematic due to the increased incidence, in this population, of chronic epithelial defects, poor blink rate, infections, and wound dehiscence or slippage associated with slower wound healing.

The preoperative evaluation should also address any neurologic or intraocular factors that could compromise the final visual result, such as other media opacity, uncontrolled glaucoma, amblyopia,