Clinical and Tomographic Outcomes of Long Arc-Length Intrastromal Corneal Ring Segment Implantation in Central Keratoconus

Abstract

Purpose To assess the outcomes of implanting a long arc-length intrastromal corneal ring segment (ICRS) in central hyperprolate keratoconus (KC). Methods Retrospective study enrolling patients with moderate to advanced hyperprolate KC that were submitted to long arc-length ICRS implantation (Ferrara™ or Keraring®). The clinical measurements taken included manifest refraction, spectacle corrected distance visual acuity (CDVA, logMAR scale), and corneal tomographic analysis (Oculus Pentacam HR (OCULUS Optikgerate GmbH, Wetzlar, Germany). Clinical and tomographic changes were assessed. All examinations were performed before and after surgery. Results Thirty-five eyes of 31 patients (71.0% men, n=22) with a mean±SD age of 28.25±11.42 years were enrolled. Median (IQR) follow-up was 19.3 (9.93–23.03) months. Twenty-five Keraring® and ten Ferrara™ ICRS, including 16 (45.7%) with progressive thickness, were successfully implanted, with no intraoperative or postoperative complications. CDVA improved from 0.70±0.40 to 0.38±0.32 logMAR (p < 0.001) and the spherical equivalent decreased from −1.94±2.81 to −0.16±1.93D (p < 0.001). Overall, 82.8% gained at least one line; no patient lost lines postoperatively. All anterior but not posterior keratometric parameters decreased significantly. Maximum elevation of both corneal surfaces, asphericity, vertical Coma-like aberration and the total higher-order aberrations decreased significantly with the procedure (all p < 0.05). The 6-month safety index (ratio of postoperative to preoperative CDVA) was 2.85. No complications occurred during or after the procedure. Conclusions These results suggest that implanting a long arc-length ICRS is a well-tolerated and effective procedure associated to improvement of visual and tomographic outcomes in patients with central hyperprolate keratoconus.