Penetrating Keratoplasty (PK)
PK is a full-thickness transplant procedure, in which a trephine of an appropriate diameter is used to make a full-thickness resection of the patient’s cornea, followed by placement of a full-thickness donor corneal graft. Interrupted and/or running sutures are placed in radial fashion at equal tension to minimize post-operative astigmatism (Figure 2). Later, the sutures are removed selectively to reduce the amount of astigmatism present. A transplant can last decades with proper care (Figure 3). While once the most prominent type of corneal transplant, PK has been supplanted by partial thickness techniques for endothelial dysfunction without significant stromal scarring. PKs are performed primarily for visually significant stromal scarring, opacities with an uncertain status of the endothelium or significant posterior corneal involvement, corneal ectasia (such as keratoconus and pellucid marginal degeneration, especially if there is history of hydrops), combined stromal and epithelial disease (such as Peters anomaly), and infectious or non-infectious corneal ulcerations or perforations (1, 14). A variant of the procedure, the mini-PK, can be used to treat more focal defects in the cornea