Indications and long-term outcomes of repeat optical penetrating keratoplasty

Purpose: To determine the indications, practice pattern of immunomodulation (IM), and outcomes of repeat optical penetrating keratoplasty (OPK). Methods: Of 4454 OPKs performed from 2016 to 2023, 259 (5.81%) were OPK following previous failed OPKs (OPK/OPK) and these were included in the study; those with follow-up <1 m were excluded. Indications for primary, last graft, risk factors, and IM use were recorded. Hazard’s ratio of factors for graft failure was computed. Graft survival (clear graft at last follow-up) and graft survival time were analyzed. Results: Prior OPK failed twice in 69 (26.64%), thrice in 41 (15.83%), and >4 times in 13 (5.01%). Indications for repeat graft included rejection (83.78%), HSV (14.67%), and infection (13.90%). Pre-op IM was used in 18.91%, while post-op was in 7%. Younger age, prior therapeutic PK, corneal scars post infections, anterior segment dysgenesis, >2 quadrants deep vascularization, and >2 failed grafts increased risk of graft failure. Visual acuity improved at 1 month and declined after 3 months. 39% of grafts survived until last follow-up (mean 31.5 m), and the median survival time was 36 m (CI: 30.2 to 45.8 m). Conclusion: OPK/OPK subset constitutes close to 6% of all OPKs performed, and 39% of these regrafts remain clear over a mean follow-up of 31 m. Half regrafts fail 36 m post-OPK. More than 80% of these grafts fail post rejection, and one-third post infection. Males undergo repeat OPKs more. Younger age, deep vessels, previous infections, and >2 grafts pose higher risk of failure to subsequent grafts. Current IM use is limited to 7–20% with pre-existing high risk and needs further studies to enhance graft survival in these complex situations.