PKP (penetrating keratoplasty) has been the standard of care for many years and most physicians are very familiar with the postoperative care. It provides excellent vision with the appropriate glasses or contact lenses in most cases. It does require frequent visits to the doctor to measure the cornea, prescribe glasses, and take care of the stitches.
The cornea is a transparent dome on the front of the eye. Corneal edema (swelling) produces decreased vision due to loss of transparency of this normally clear tissue. The swelling arises from a loss of endothelium, a thin layer of cells found on the back surface of the cornea. These cells are not capable of dividing or repairing themselves. The only treatment for visually significant corneal swelling is to replace these cells.
Until recently, the only way to replace endothelial cells was to replace the entire cornea with a donor cornea using a penetrating keratoplasty (PKP). Unfortunately the wound can take years to heal so the new cornea is sutured in place with very fine stitches left in place for a long time to maintain strength and stability. After the operation, it usually takes several months to years to obtain your best vision. It is very difficult to predict the final curvature of the cornea; so after surgery, glasses or contact lenses are required in the majority of cases. If the stitches break, there may be a feeling like having sand in the eye, and removal of the stitches may change the curvature of the cornea requiring new glasses. In addition, the broken stitches may produce a corneal infection requiring the use of antibiotics to treat the infection and can rarely lead to graft failure.
PKP procedures are less commonly performed today but are still necessary if all of the layers of the cornea are affected such as scarring, infection or trauma. In these cases, partial transplantation will not restore the clarity of the cornea.