Visual And Topographic Outcomes After Corneal Allogeneic Intrastromal Ring Segments (Cairs) For Keratoconus: A Systematic Review And Meta-Analysis

To date, several clinical studies have attested the efficacy of CAIRS in providing improved visual and topographic outcomes in keratoconic eyes. However, the outcomes are reported in heterogenous case series with highly varying results and low numbers of included patients. Herein, in this meta-analysis we seek to provide a structured synopsis of the currently available clinical evidence on the efficacy and safety of the CAIRS procedure.

University Eye Clinic of Heidelberg.

In this systematic literature review and meta-analysis (ID: CRD42024612508) original peer-reviewed clinical studies on the effect of CAIRS in eyes with keratoconus were included. The primary effect measure was the difference in corrected distance visual acuity (CDVA) before and after CAIRS. Additionally, changes in uncorrected distance visual acuity (UDVA), spherical equivalent (SE), cylinder, flat keratometry, steep keratometry, maximum keratometry (Kmax), mean keratometry, thinnest corneal thickness, and higher order aberrations (HOAs) due to CAIRS were analyzed and compared using a random effects model. In addition, postoperative complications were documented.

Overall, 14 studies with a total of 442 eyes from 353 patients were included in the meta-analysis. Our analysis found that CAIRS implantation led to significant improvement of the CDVA and UDVA in keratoconus patients. The spherical equivalent as well as the refractive cylinder were significantly reduced after CAIRS. Additionally, CAIRS implantation significantly reduced the topographic keratometry values and multiple HOA parameters, with no significant change in the thinnest corneal thickness. One severe adverse event (0.2%) was reported with an acute rejection due to unknown causes leading to the explantation of CAIRS. Two patients (0.5%) lost one line of CDVA after CAIRS. No other severe adverse events were reported.

This meta-analysis demonstrates that CAIRS implantation is an effective procedure that can significantly improve UDVA, CDVA, and topographic outcomes in keratoconus eyes with low complication rates.