Author’s Disclosure Block: Louis Vaudoisey, none; Johanna Choremis, none; Guillermo Rocha, none; Julia Talajic, none

Abstract Body
Purpose: To evaluate the safety and efficacy of Corneal Allogeneic Intrastromal Ring Segments (CAIRS) in treating moderate to severe Keratoconus (KC). Specifically, it aims to assess the effectiveness of KeraNatural, eye-bank prepared CAIRS tissue, in improving visual acuity and explores its potential to delay or obviate the need for corneal transplantation. Additionally, the study investigates the topographic changes post-treatment.
Study Design and Methods: A two-center retrospective study reviewed patients who underwent femtosecond laser-assisted CAIRS surgery since May 2023. Primary outcomes included best corrected visual acuity (BCVA) and uncorrected visual acuity (UCVA) at 3 months post-surgery. Pentacam analysis evaluated topographic changes in central corneal thickness (CCT), minimal pachymetry, keratometry (K1, K2, Km), and mean corneal volume (MCV). Results: 13 patients with moderate to severe keratoconus underwent CAIRS surgery. UDVA showed a median improvement of 0.46 logMAR, while BCVA improved by a median of 0.18 logMAR. Significant flattening was observed in all keratometric values, with median decreases in K1 and K2 of 0.85 and 3.35, respectively. The median decrease in mean keratometry (Km) was 1.75. MCV also decreased by 1.15. The mean follow-up time was 3.5 months. Conclusion: CAIRS emerges as an effective alternative treatment for moderate to severe keratoconus, improving both visual acuity and topographic values. These results demonstrate that CAIRS implantation is safe and provides favorable visual and keratometric outcomes for suitable keratoconus patients, positioning it as a promising therapeutic option for managing corneal ectasia.