Long-Term Follow-up of Intrastromal Corneal Ring Segments (210-Degree Arc Length) in Central Keratoconus With High Corneal Asphericity

PURPOSE: To assess the long-term outcomes of implanting intrastromal corneal ring segments (ICRSs) to correct central keratoconus with a high corneal asphericity value. METHODS: Forty-three eyes with central keratoconus with a corneal asphericity value ≥-1.00 were evaluated before and after implanting an inferior 210-degree arc-length Ferrara-type AFR5 ICRS (AJL Ophthalmic, Spain). Logarithm of the minimum angle of resolution uncorrected (UDVA) and best-corrected (CDVA) distance visual acuity, corneal asphericity, root mean square for coma-like aberrations computed for the Zernike terms Z (3, 1) and Z (3, -1), and residual refractive errors analyzed using vector analysis were recorded before and at all follow-up visits. The postoperative follow-up duration was 3 years in all cases. RESULTS: Mean UDVA (logarithm of the minimum angle of resolution scale) rose from 1.18 ± 0.59 to a postoperative 0.53 ± 0.39 after ICRS implantation (P 0.05). The spherical equivalent declined steeply after ICRS implantation (P 0.05). CONCLUSIONS: These results suggest that implanting a single, inferior, 210-degree arc-length Ferrara-type ICRS is a safe, effective, and stable procedure for treating patients with central hyperprolate keratoconus.