Concentric Intrastromal Corneal Ring Implantation for Asymmetric Keratoconus: A Case Series

Purpose: This study evaluates the outcomes of a novel concentric intrastromal corneal ring segment (ICRS) implantation technique in patients with asymmetric keratoconus who experienced unsatisfactory results from previous protocols.Materials and methods: This case series included 3 patients with asymmetric keratoconus who underwent concentric ICRS implantation.The technique strategically positioned 210 and 140 ring segments in different optical zones to enhance corneal regularity and visual outcomes.All procedures were performed manually by the same surgeon.Preoperative and postoperative assessments included visual acuity, corneal topography, and aberrometric analysis using Pentacam.Results: All 3 patients significantly improved corneal regularity and visual parameters.A 40-year-old male (case 1) achieved enhanced central corneal flattening and reduced comatic aberration after adding a 210 segment concentric to the initial 140 implant.A 36-year-old male (case 2) with enantiomorphic keratoconus showed improved visual quality and reduced asymmetry following the combined implantation of 210 and 140 segments.A 23-year-old male (case 3) achieved significant astigmatism reduction and visual acuity improvement with a 210 segment in the 6 mm zone and a 140 segment in the 5 mm zone. Conclusion:The concentric ICRS implantation technique effectively treated asymmetric keratoconus with unsatisfactory outcomes from prior protocols.This approach significantly improved visual acuity, corneal flattening, and aberration reduction.Further studies are warranted to validate these findings in larger cohorts.