Therapeutic penetrating keratoplasty for recalcitrant microbial keratitis: An update

Therapeutic penetrating keratoplasty (TPK) is a surgical procedure for salvaging medically refractory infectious keratitis. By replacing diseased, infected host corneal tissue with a full-thickness donor cornea, TPK aims to eliminate infection, preserves globe integrity and maintain vision. However, recurrence of infection in the graft remains a significant concern, particularly in cases caused by resistant organisms such as Acanthamoeba, Pythium, microsporidia, and certain bacterial and fungal pathogens. Although often curative, TPK carries a higher risk of endothelial rejection, reduced graft survival, and increased complications due to its open-sky approach. Lamellar keratoplasty, particularly deep anterior lamellar keratoplasty, has emerged as a promising surgical alternative in cases where the infection has spared the deeper corneal layers. Compared with full-thickness therapeutic keratoplasty, it offers advantages including improved graft survival, lower rejection rates and fewer postoperative complications. Nevertheless, recurrence may still occur in deep or extensive infections, and advanced cases with descemetocele, perforation, or limbal or scleral involvement often still require TPK. This article on TPK summarizes peer-reviewed literature from the past decade, incorporating recent advances in corneal surgery while placing the modern-day application of classically described techniques into perspective to strengthen surgical decision-making. Emphasis is placed on resistant pathogens, surgical indications, preoperative evaluation, anesthesia considerations, operative techniques, prognostic factors, and postoperative management strategies. Through this review, ophthalmic surgeons are expected to gain practical guidance for optimizing outcomes in complex corneal infections while addressing the challenges posed by resistant and atypical pathogens across diverse clinical scenarios.