Long-Term Outcomes of Progressive Thickness Intrastromal Corneal Ring Segments for Keratoconic Eyes: A 4-Year Follow-Up Publisher Pubmed



Khorraminejad M ; Jadidi K ; Almaliky Z ; Nejat F ; Aghamolaei H ; Narooienoori F ; Jumah RQ ; Afkhamizadeh F ; Majdi A
Source: Cornea Published:2025

Abstract

Purpose: – To evaluate the long-term visual, refractive, and tomographic outcomes of progressive thickness intrastromal corneal ring segment implantation using the KeraRing AS in patients with keratoconus (KC).Methods: – In this historical cohort study, 36 eyes from 36 patients with progressive KC underwent femtosecond-assisted KeraRing AS (Mediphaco, Brazil) implantation. Preoperative and postoperative uncorrected and corrected distance visual acuity, spherical equivalent (SE), astigmatism, keratometric indices, and pachymetric parameters were analyzed at 1- and 4-year follow-ups.Results: – Uncorrected distance visual acuity improved from 0.71 ± 0.36 to 0.34 ± 0.27 logarithm of the Minimum Angle of Resolution (logMAR) at 1 year and 0.28 ± 0.26 logMAR at 4 years (P <0.001). Corrected distance visual acuity improved from 0.33 ± 0.20 to 0.22 ± 0.16 logMAR at 1 year and 0.16 ± 0.13 logMAR at 4 years (P <0.001). SE improved from −5.38 ± 3.03 diopters (D) to −1.00 ± 1.48 D at 1 year but showed partial recurrence to −1.68 ± 1.83 D at 4 years (P = 0.011). Mean keratometry decreased from 46.52 ± 2.41 D to 43.82 ± 2.40 D at 1 year and increased significantly to 44.94 ± 2.18 D at 4 years (P <0.001). Corneal thickness parameters remained stable throughout the follow-up period.Conclusions: – KeraRing AS implantation provides significant initial improvements in visual and topographic parameters in progressive KC. However, notable regression occurs after 1 year, with significant increases in spherical power, SE, and all keratometric parameters between 1 and 4 years. This regression pattern emphasizes the importance of long-term monitoring and potential need for additional interventions. Copyright © 2025 Wolters Kluwer Health, Inc. All rights reserved.