Postoperative Corneal Epithelial Remodeling After Intracorneal Ring Segment Procedures for Keratoconus: An Optical Coherence Tomography Study

Abstract

PURPOSE: To assess epithelial corneal remodeling by anterior segment optical coherence tomography (AS-OCT) after intracorneal ring segments (ICRS) implantation in keratoconic eyes. METHODS: This prospective observational study included patients with keratoconus receiving ICRS of different arc lengths according to their tomographic pattern. AS-OCT and corneal topography (Scheimpflug camera) were performed before and 1, 3, and 6 months after surgery. Corneal pachymetry mapping was performed and total corneal and epithelial thicknesses (3-mm central and 16 points on 6-mm zone) were measured over the pupil center using AS-OCT. Topographic parameters were also assessed. RESULTS: A total of 68 keratoconic eyes were analyzed (Amsler-Krumeich stages 1 to 4) in four groups of 17 eyes: 210° ICRS, 320° ICRS, double 160° ICRS, and single 160° ICRS. Corneal pachymetry mapping revealed that epithelial thickness increased significantly in the internal zones juxtaposed to the ICRS without smoothing during the postoperative period ( P < .05). Mean maximum epithelial thickness increased from 67 ± 6 to 79 ± 7 µm for 210° ICRS, 66 ± 9 to 82 ± 4 µm for 320° ICRS, 63 ± 6 to 78 ± 7 µm for double 160° ICRS, and 62 ± 5 to 77 ± 5 µm for single 160° ICRS ( P < .0001). Significant epithelial thickening at the apex of the cone was observed in all groups ( P < .05). CONCLUSIONS: Significant epithelial thickening occurs after ICRS implantation adjacent to the ICRS to compensate for the ridge created with a thickening of epithelium over the cone due to regularization of the stromal surface. [ J Refract Surg . 2021;37(6):404–413.]

Recombinant Human Nerve Growth Factor (Cenegermin)–Driven Corneal Wound Healing Process: An Evidence-Based Analysis

“…Thanks to its dedicated caliper tool, it also allowed us to accurately document changes by measuring the stromal thickness at the thinnest part. AS-OCT is an effective tool for systematic anterior-segment imaging, allowing the detailed detection of the front-to-back layered corneal structure for quantitative analysis and monitoring of the healing process (David et al, 2021). Using AS-OCT granted us quantitative monitoring of structural changes in NK treated by cenegermin, obtaining a better understanding of rh-NGF-driven corneal wound healing process.…”

Asymmetric Intrastromal Corneal Ring Segments with Progressive Base Width and Thickness for Keratoconus: Evaluation of Efficacy and Analysis of Epithelial Remodeling

“…They showed, by ultrasound imaging, that epithelial filling occurred in the concave anterior stromal groove produced after ICRS implantation for the treatment of myopia [ 22 ]. David et al analyzed SD-OCT results for nonasymmetric ICRS implantation (Ferrara type) for keratoconus and found significant epithelial thickening in the internal zones juxtaposed with the ICRS; they showed that this epithelial thickening differed between ICRS and keratoconus types [ 23 ]. The stroma of the cone apex also seems to be remodeled following ICRS implantation, as also shown by the thickening of the epithelium 23 , and could be the result of stromal flattening.…”

“…Reinstein et al showed that ICRS implantation for myopia treatment induced epithelial filling in the concave anterior stromal groove [ 22 ]. In anterior-segment optical coherence topography (AS-OCT) analyses on different types of keratoconus, David et al showed that epithelial thickening in the internal zones contiguous to a symmetric ICRS differed between ICRS types, and reported epithelial thinning above the ICRS, with no smoothing of this effect after six months of follow-up [ 23 ]. Analyses of epithelium remodeling after asymmetric ICRS implantation are useful for determining whether the cornea has been regularized by ICRS implantation and for analyses of the asymmetric stromal effect of the asymmetric ICRS.…”

Effect of intrastromal corneal ring segments on in vivo corneal biomechanics in keratoconus: 1-year results

“…13 The cycle of progressive focal weakening is interrupted by the improvement in curvature and increased thickness (induced by epithelial thickening adjacent to the ICRS to compensate for the ridge created with a thickening of the epithelium over the cone because of regularization of the stromal surface), and they tend to a mildly stiffer response with the structural support of the ICRS. 22 A recent study by Torres-Netto et al investigated the early biomechanical changes induced by ICRSs in ex vivo porcine eyes and showed a significantly effective change in modulus and increase in IOP measurement after ring implantation. 23 This is likely because of the difference in corneal response to load with the added structural support of the rings, similar to the current study, and not because of stiffening of the native tissue, as stated by the authors.…”