Corneal Allogenic Intrastromal Ring Segments For The Treatment Of Keraroconus CAIRS in Keratoconus

Purpose: To assess the clinical outcomes of Corneal Allogenic Intrastromal Ring Segments (CAIRS) as a therapeutic approach for keratoconus (KC), with a focus on visual acuity, refractive status, and corneal topographic parameters. Methods: This retrospective study included 24 eyes from 22 patients with keratoconus who experienced suboptimal visual acuity with spectacles and were intolerant to contact lenses. All patients underwent femtosecond laser-assisted CAIRS implantation using KeraNatural allogenic corneal segments. Follow-up evaluations were conducted at 1 day, 1 week, 1 month, 6 months, and annually thereafter. Outcome measures included uncorrected visual acuity (UCVA), best spectacle-corrected visual acuity (BSCVA), refractive error, and tomographic keratometry. Results: Statistically significant improvements were observed in UCVA, BSCVA, and refractive parameters. Mean UCVA improved from 1.1 ± 0.47 to 0.49 ± 0.30 logMAR (P < 0.001), and BSCVA from 0.35 ± 0.15 to 0.25 ± 0.22 logMAR (P = 0.001). A total of 92% of eyes gained ≥ 3 lines of UCVA, and 46% gained ≥ 6 lines. Manifest astigmatism decreased from − 9.97 ± 4.21 D to − 3.70 ± 1.69 D (P < 0.001). A consistent reduction in Kmax, K1, and K2 values indicated corneal flattening in all eyes. Two eyes required segment adjustments due to excessive flattening, and two developed localized inferior pannus. Conclusion: CAIRS implantation demonstrates promising efficacy in improving visual acuity and corneal tomographic parameters in keratoconus patients. Further research with extended follow-up is warranted to establish the long-term safety and durability of this technique.