Recurrence Rates and Predictive Risk Factors of Keratoconus After Penetrating and Deep Anterior Lamellar Keratoplasty

The aim of this study was to evaluate recurrent ectasia as a long-term complication after penetrating keratoplasty (PK) and deep anterior lamellar keratoplasty (DALK) and to further characterize its diagnostic criteria and associated risk factors.

This retrospective study included 136 eyes (50 PK, 86 DALK) with at least 3 years of follow-up after complete suture removal. Corneal tomography was performed at standardized intervals, and recurrence was defined based on modified Global Delphi criteria, incorporating keratometric, pachymetric, and visual changes. In addition, symmetry indices, elevation parameters, and Kmax values of the anterior and posterior corneal surfaces were evaluated.

Recurrent ectasia was detected in 28 eyes (20.6%), with rates of 22.1% after DALK and 18.0% after PK, with no statistically significant difference between the groups (P = 0.569). The mean time to recurrence was 40.7 ± 26.0 months after suture removal. Smaller donor and host corneal diameters were significantly associated with recurrent ectasia in both DALK and PK groups, and in the overall cohort (all P < 0.001). Progressive changes in K1 (P = 0.049), K2 (P = 0.002), Kmean (P = 0.002), minimum corneal thickness (P = 0.021), apex thickness (P = 0.004), and astigmatic vectors (P = 0.014) were identified as key diagnostic markers in the overall cohort, whereas Kmax was not reliable at the final visit (P = 0.733).

These findings suggest that smaller graft diameter was identified as a significant risk factor for recurrence. Objective keratometric and pachymetric criteria may improve early detection and standardization of postoperative follow-up.