Correlation of graft–host junction alignment and epithelial thickness with postoperative astigmatism following corneal transplantation

Abstract

Purpose: This study aimed to investigate the relationship between the graft–host junction (GHJ) configuration and postoperative astigmatism in patients who underwent penetrating keratoplasty (PK) or deep anterior lamellar keratoplasty (DALK) and to examine whether variations in epithelial thickness are associated with astigmatic outcomes. Methods: A retrospective analysis was conducted on 54 phakic eyes (30 PK and 24 DALK) with a minimum follow-up of 12 months. GHJ morphology was evaluated using anterior segment optical coherence tomography (AS-OCT). Epithelial thickness was measured in the steepest and flattest corneal areas using RTVue XR. Astigmatism was quantified by auto-refraction, keratometry, and corneal topography. Based on GHJ configuration, eyes were classified as either well-aligned or malaligned. Results: Malalignment of the GHJ was observed in 87.1% of cases. Eyes with malaligned junctions exhibited significantly higher astigmatism across all measurement techniques (P < 0.05). The correlation between GHJ configuration and astigmatism was strong in the DALK group but did not reach statistical significance in the PK group. Malalignment was more frequent following PK than DALK (P = 0.002). The epithelial thickness was significantly lower in the flattest zone (P = 0.006), while the increase in the steepest zone was not significant (P = 0.4). Conclusion: Optimal graft–host junction alignment remains a key determinant of refractive success following corneal transplantation. Integrating intraoperative OCT, femtosecond-assisted trephination, and individualized suturing strategies may help reduce postoperative malapposition and astigmatism. Future prospective studies incorporating epithelial remodeling and visual quality analysis will further clarify the mechanisms linking structural alignment and optical performance after keratoplasty.