Long-Term Visual, Refractive and Topographic Outcomes of KeraRings Combined with Accelerated Transepithelial Crosslinking for Management of Different Grades of Progressive Keratoconus: A Retrospective Cohort Study

Abstract

Purpose: To evaluate long-term visual, refractive, and topographic outcomes of KeraRings intrastromal implantation combined with accelerated transepithelial cross-linking for management of different stages of progressive keratoconus. Materials and Methods: This retrospective cohort study included 70 eyes of 70 patients with Amsler-Krumeich grades 1 to 4 keratoconus. They were divided into two groups: group-A included 37 eyes with grades 1-2 keratoconus, and group-B included 33 eyes with grades 3-4 keratoconus. Both groups underwent combined Keraring implantation with TCXL treatment. The main outcome measures included the preoperative and postoperative visual acuity, refraction, keratometry readings, and pachymetry. Results: At postoperative month 60, group-B exhibited significantly higher values of all mean uncorrected distance visual acuity (UDVA), corrected distance visual acuity (CDVA), sphere/cylinder/spherical equivalent/defocus equivalent (DEQ), and K1/K2/Kaverages/Kmax parameters compared to that of group A. However, group-A exhibited better stability of postoperative improvements. Keratoconus progression (KCP) was greater in group-B (45.5\%) than group-A (10.8\%). Two eyes revealed segments' migration while one eye showed tunnel vascularization and opacification with segments' migration. Conclusion: The diagnostic criteria of preoperative-KCP are not adequate for the diagnosis of postoperative-KCP following ICRS implantation. UDVA and Kaverage(posterior) seemed to be more sensitive parameters than K max in documenting early postoperative-KCP. We suggest that deterioration of UDVA >= 0.10 log MAR and/or K average(posterior) >= 0.25 D are highly suspicious of post-ring implantation keratoconus progression (PR-KCP). The occurrence of two of the following parameters: Kmax >= 0.50 D, Kaverageanterior >= 0.50 D, K average(posterior)>= 0.25 D, or pachymetry >= 1.5\% thinning, is diagnostic of PR-KCP. The occurrence of two or more of the following parameters: Kmax >= 0.50 D, Kaverage(anterior)>= 0.50 D, Kaverage(posterior)>= 0.25 D, pachymetry >= 1.5\% thinning or UDVA >= 0.10 logMAR, is diagnostic of PR-KCP. We also suggest that Kmax >= 0.75 D alone is diagnostic of PR-KCP.