Corneal Transplant Failure Is Associated With a High Percentage of Epithelial Downgrowth: A 24-Year Retrospective Clinical and Histological Study From a Single Academic Institute

Purpose: Epithelial downgrowth (EDG) is a relatively infrequent complication of intraocular surgery or eye trauma. The literature is limited on this condition, and it remains a diagnostic challenge, both histologically and clinically. We have conducted a 24-year single-institution clinical and pathological retrospective review of epithelial downgrowth cases. Methods: Cases of histologically suspected EDG were identified through the electronic record system at Casey Eye Institute Pathology Laboratory. Keywords entered in the search included “epithelial ingrowth” or “epithelial downgrowth” spanning the dates January 1999 to March 2023. Results: Fifty-eight patients with suspected EDG on pathology were included in the study. Most patients had a complex surgical history, defined as 2 or more intraocular surgeries (64%; n = 37). History of nonsurgical ocular trauma was noted in 19% of cases (n = 12). The highest documented clinical presentations included corneal graft failure (52%; n = 30) and bullous keratopathy (12.5%; n = 8). Of the graft failure cases, 53% were penetrating keratoplasties (n = 16). EDG was clinically suspected in 16% of cases (n = 9). Overall, there has been an uptrend of histologically suspected cases from 1999 to present at our institute, with the highest number of suspected cases in the years 2018 to 2023 compared with the 1999 to 2005, 2006 to 2011, and 2012 to 2017 time intervals. Conclusions: EDG is diagnostically complex, and many suggestive features on pathology are not definitive. The frequency of cases with clinical suspicion for EDG and/or histopathologic features raising consideration of EDG have increased over a 24-year period. This study underscores the need for further research to aid in definitive diagnosis of EDG.