Causes of corneal transplant failure: a multicentric study.

Purpose: To identify the causes of failure of the different surgical corneal graft techniques: penetrating keratoplasty (PK), deep anterior lamellar keratoplasty (DALK), Descemet stripping automated endothelial keratoplasty (DSAEK) and Descemet membrane endothelial keratoplasty (DMEK).

Methods: This multicentric retrospective study enrolled a consecutive cohort of patients who had undergone any type of keratoplasty between 2001 and 2016. The clinical data were obtained from the patient's medical records, following ethical guidelines, permissions and data protection. The main outcome measured in the study was the cause of graft failure, defined as any irreversible loss of graft transparency capable of compromising vision. The main causes of graft failure were classified as follows: (A) primary graft failure (PGF), (B) immunological rejection, (C) non-rejection (which includes endothelial decompensation without rejection, IOP elevation/glaucoma, diseases of the ocular surface, recurrence of the primary disease, wound dehiscence/hypotonia and trauma, among others) and (D) specific causes of lamellar keratoplasty failure. A descriptive study of the obtained data was carried out. The distribution of the causes of failure was evaluated according to the type of corneal transplant.

Results: Our research included a cohort of 571 keratoplasty failures, of which 509 met the inclusion criteria. The analysis of the causes of the PK failure showed that immunological allograft rejection represented the main cause, with 28.2% of the failures, followed by surface diseases (17.8%) and endothelial decompensation without rejection (17.3%). For the PK re-grafts group, the main cause of failure was immunological allograft rejection (34.0%), followed by diseases of the ocular surface (18.5%). For the DALK group, the failures mainly occurred due to surface diseases such as limbal stem cell insufficiency, infectious keratitis, keratolysis or persistent epithelial defect (37.8%). However, the main reason for failure in the DSAEK group was endothelial decompensation without rejection (31.9%) while primary graft failure was the main cause of failure in the DMEK group (64.1%).

Conclusion: The main reason for failure in PK was immunological allograft rejection, both in primary and secondary transplants. The leading causes for failure were diseases of the ocular surface in the DALK population, endothelial decompensation without rejection in DSAEK and primary graft failure in DMEK.