Eyeworld

72 | EYEWORLD | WINTER 2026 C ORNEA by Ellen Stodola Editorial Co-Director About the physicians Stephen Armenti, MD, PhD Assistant Professor of Clinical Ophthalmology Medical Director Scheie Eye Institute Penn Medicine Philadelphia, Pennsylvania Bennie Jeng, MD William F. Norris and George E. de Schweinitz Professor Chair Department of Ophthalmology Director Scheie Eye Institute Penn Medicine Philadelphia, Pennsylvania problem. Dr. Armenti agreed that the choice for PK is clear in patients with a corneal perforation from an infection or a non-healing ulceration. "A full thickness graft is usually going to be the way to go with those," he said. Dr. Jeng added that physicians may forget that there may be certain individuals in whom PK would be the reasonable option, and it's im- portant to have a conversation with the patient. In terms of how often he's still performing PK, Dr. Armenti said there are patients with keratoconus that still require corneal transplant with a PK or DALK. Patients who are candi- dates for those procedures may not tolerate a contact lens to correct their vision or have very advanced disease. Patients with corneal dystro- phies who develop deposits in the anterior half of the cornea may also benefit from a DALK or PK because the pathology exists primarily in the anterior corneal layers. "I'd say about 90% of the corneal transplants I perform are endotheli- al keratoplasties; maybe about 10% are pene- trating keratoplasty." He added that the recent approval of epi- thelium-on crosslinking may further expand the pool of patients who are candidates for cross- linking and further decrease the rate of patients requiring a PK. Another intervention that may impact what we offer patients, Dr. Armenti said, are cell-based therapies and newer additive cornea procedures, like corneal allogenic intrastromal ring segments (CAIRS). CAIRS has the poten- tial to improve visual acuity in patients with keratoconus without the risks of a full thickness transplant. "That may start to be employed more commonly to correct vision," he said. This is also decreasing the need for keratoplasty for keratoconus. Dr. Armenti said there are some instances where he has attempted multiple EKs—for ex- ample, in a patient who had previous glaucoma surgery and has endothelial damage—that have resulted in failures; it still may make sense to consider another EK before doing a PK, but a PK may end up being necessary. One concept that Dr. Jeng highlighted was "habitual visual correction," which he said re- fers to what the patient generally walks around with. "Let's say they had a PK, and for the last A s patterns in corneal transplant pro- cedures continue to shift, Stephen Armenti, MD, PhD, and Bennie Jeng, MD, weighed in on where PK still fits into the algorithm. "We've all seen the data that EK, for the last decade or so, has been the more commonly done keratoplasty procedure in the U.S., and now DMEK specifically is the most commonly done," Dr. Jeng said. A shift in procedure pref- erence started to occur around 2011, he said, adding that this is when Eye Bank Association of America data suggests that EK took over PK as the more commonly performed procedure. However, worldwide, PK is still by far the more commonly done procedure, especially in devel- oping countries where corneal scarring from infections is a leading indication for corneal transplant surgery. The shift away from PK has been multifac- eted over the years, Dr. Armenti said. First, he said the advent of EK provided a procedure with a lower risk of rejection, more predictability, and faster recovery. More recently, there's been a further shift, particularly in patients with keratoconus, away from PK due to the expanded indications for corneal crosslinking. For those who would still need transplantation, deep an- terior lamellar keratoplasty (DALK) is becoming more popular. However, Dr. Armenti noted that PK is a great option for patients in whom an EK is not indicated—if patients have failed an EK sur- gery before or they have any pathology in the front 90% of the cornea (in the stroma, such as anterior scars after infectious keratitis, etc.). As EK only addresses the endothelial cells of the cornea, if there is a primary endothelial disease with the rest of the cornea relatively clear, it's a good option. If the pathology is anywhere other than the endothelium and Descemet's mem- brane, it's often not a good option. While some might think anything can be replaced with lamellar surgery, Dr. Jeng said this is not always the case. When there is a combined problem with the stroma and the endothelium, whether it's scarring or a previ- ous perforation that is now sealed, these are all much more amenable to PK, he said, because doing posterior lamellar surgery doesn't fix the Where PK still fits as a choice for corneal transplantation

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