Additionally, PKs carry a higher lifetime risk of wound dehiscence due to the compromised tectonic strength that comes from a full-thickness wound. There is a higher risk of allograft rejection compared with other keratoplasty types. Frequently, there is substantial postoperative refractive error due to high regular or irregular astigmatism of the graft, and a higher chance of requiring rigid gas permeable contact lens wear to correct astigmatic error. However, postoperative recovery time is relatively long, sometimes taking years to achieve best-corrected visual acuity. A full-thickness graft also eliminates optical interface related visual problems that may exist with lamellar transplants with a stroma-stroma interface. PK grants the ability to treat disease in the epithelial, stromal, and endothelial layers. Grafts can also be secured with a running suture (C) or a combination of running and interrupted sutures (D).įigure 3: A PK graft, with all sutures removed, remains crystal clear 30 years after the procedure.įigure 4: A mini-PK graft performed for a focal corneal perforation. Figure 2: PK grafts with 16 (A) and 24 (B) interrupted sutures. A variant of the procedure, the mini-PK, can be used to treat more focal defects in the cornea (Figure 4). 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). While once the most prominent type of corneal transplant, PK has been supplanted by partial thickness techniques for endothelial dysfunction without significant stromal scarring. A transplant can last decades with proper care (Figure 3). Later, the sutures are removed selectively to reduce the amount of astigmatism present. Interrupted and/or running sutures are placed in radial fashion at equal tension to minimize post-operative astigmatism (Figure 2). 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.