VISUAL AND TOMOGRAPHIC OUTCOMES OF LONG ARC-LENGTH ICRS IMPLANTATION IN MODERATE TO ADVANCED KERATOCONUS

To assess the outcomes of implanting an intrastromal corneal ring segment (ICRS) of 300º or above arc-length in moderate to advanced hyperprolate keratoconus (KC).

Cornea Unit, Department of Ophthalmology, Centro Hospitalar Universitário do Porto

Retrospective study enrolling patients with moderate to advanced hyperprolate KC that were submitted to femtosecond laser-assisted implantation of a long arc-length ICRS (Ferrara or Kearing). The clinical measurements taken included manifest refraction, best-corrected distance visual acuity (BCDVA, logMAR scale), and corneal tomographic analysis (Oculus Pentacam HR (OCULUS Optikgerate GmbH, Wetzlar, Germany)). Changes in keratometry, asphericity, and the root mean square (RMS) for total higher-order and coma-like aberrations for a pupil size of 4.5 mm were evaluated. All examinations were performed before surgery and at least 3 months after surgery.

Sixteen eyes of 15 patients (60% men) with a mean±SD age of 25.36±8.76 years were enrolled. Mean±SD BCDVA improved from 0.68±0.12 to 0.43±0.05 LogMAR (P = 0.014) and the spherical equivalent reduced from -2.19±0.58 to -0.69±0.33D (P = 0.025). All keratometric parameters reduced significantly (all P < 0.001; mean±SD 54.17±42 vs 48.02±2.65 for K1, 58.87±4.89 vs 51.19±2.59 for K2 and 69.90±7.90 vs 61.58±4.60 for Kmax). The asphericity reduced significantly (+0.96±0.44; P < 0.001). The absolute values of horizontal and vertical Coma-like aberrations reduced -0.32±0.17 (P = 0.034) and -0.38±0.22 (P = 0.055), respectively, and the total higher-order aberrations were also lower after ICRS implantation (-1.21±0.19, P < 0.001). No complications occured during or after the procedure.

These results suggest that implanting a long arc-length ICRS is a safe and effective procedure for treating patients with moderate to advanced hyperprolate keratoconus and clear cornea, leading to improvement of visual and tomographic outcomes.