Retrospective Study of Corneal Tissue Addition Keratoplasty for Keratoconus and Post-Refractive Ectasia

This retrospective, multi-center observational study evaluates clinical outcomes in patients with keratoconus or post-refractive ectasia who previously underwent Corneal Tissue Addition Keratoplasty (CTAK) as part of routine clinical care. The primary objective is to evaluate changes in corneal curvature, measured by steep keratometry (K2), maximum keratometry (Kmax), and mean keratometry (Kmean), from preoperative baseline to six months following CTAK. Secondary outcomes include changes in uncorrected and corrected distance visual acuity, refractive stability, documented postoperative complications, subsequent corneal transplantation, and exploratory analyses across payer categories. The study uses existing medical records from up to eight participating clinical sites, targeting up to 100 treated eyes. No study-specific intervention, patient contact, or prospective clinical assessments will occur.