Corneal Allogenic Intrastromal Ring Segments (CAIRS) for Corneal Ectasia: A Comprehensive Segmental Tomography Evaluation

Abstract

Purpose: To evaluate the visual, refractive, and tomographic results of patients with corneal ectasia treated with corneal allogenic intrastromal ring segments (CAIRS) insertion without concomitant corneal cross-linking. Methods: Fifty-two eyes from 39 patients with stable corneal ectasia and unsatisfactory visual acuity with contact lenses were included. All patients underwent CAIRS insertion with no concomitant corneal procedure at the American University of Beirut Medical Center between September 2019 and July 2022. Visual, refractive, topographic, aberrometric, epithelial, stromal, and segment thickness data were measured relative to baseline at 1 week, 1 month, and at least 3 months postoperatively. Evaluations included slit-lamp examination, manifest refraction, uncorrected (UDVA) and corrected (CDVA) distance visual acuity, and tomography using anterior segment optical coherence tomography. Results: Mean follow-up time was 6.9 ± 5.2 months. UDVA and CDVA improved from 0.97 ± 0.47 and 0.56 ± 0.19 preoperatively to 0.52 ± 0.21 ( P < .001) and 0.23 ± 0.19 ( P < .001) 3 months postoperatively. Manifest refraction spherical equivalent and cylinder improved from −6.71 ± 6.51 and −4.02 ± 2.24 diopters (D) preoperatively to −3.78 ± 4.07 D ( P < .001) and −2.35 ± 1.98 D ( P < .001) 3 months postoperatively, respectively. Maximum anterior keratometry and vertical coma decreased from 58.09 ± 7.92 D and 1.56 ± 1.09 µm to 52.48 ± 6.69 D ( P < .001) and 0.43 ± 0.77 µm, respectively ( P < .001). Corneal epithelium thickened proximal to the allogenic segment by 7.25 µm ( P < .001), whereas stromal elevation at the cone decreased from 38.61 ± 18.5 to 23.82 ± 13.4 µm, respectively ( P < .001). No major complications were observed and only 1 eye lost one line of CDVA. Conclusions: Treatment of corneal ectasia with CAIRS improved visual, refractive, topographic, and tomographic parameters. Epithelial thickening central to CAIRS, along with anterior stromal flattening is postulated to contribute to tomographic flattening and regularization. [ J Refract Surg . 2023;39(11):767–776.]

Keratoconus Management by Insertion of an Allograft Corneal Ring Segment (KeraNatural)

“…Based on the current literature, implantation of either a surgeon trephined CAIRS directly from a donor cornea [7,9] or a precut sterile packaged implant like Kera-Natural [8] is quite an effective modality to improve the refractive and keratometric aspects of the cornea in eyes suffering from progressive or nonprogressive keratoconus, iatrogenic ectasia, and pellucid marginal degeneration. Patients without corneal opacities or hydrops with a best spectacle visual acuity less than 0.5 and adequate corneal tissue at the site of implantation will most likely benefit by such a procedure either from the reduction of high-order aberrations leading to improved quality of vision, improvement of visual acuity, reduction of the refractive parameters, or because of the flattening of the conus by a potentially better contact lens fitting if this is feasible and tolerable.…”