Corneal Allograft Intrastromal Ring Segment (CAIRS) in Modern Practice for Management of Keratoconus

This review discusses the role of Corneal Allograft Intrastromal Ring Segments (CAIRSs) in the treatment of keratoconus and ectatic corneal disease, covering their mechanisms, techniques, outcomes, and prospects. The technique was developed in 2018 by reviewing protocols, surgical methods, customization, and combined approaches such as cross-linking. The review covers all aspects of CAIRS, including tissue selection, preparation, tunnel creation, and insertion technique. Clinical results show that CAIRS significantly improves visual acuity, corneal topography, and refractive stability, with success using both laser and manual techniques, especially with customization for asymmetric cones. Combining CAIRS with cross-linking enhances biomechanical stability and delays keratoplasty. Although uncommon, complications include graft rejection, extrusion, and refractive issues, and their overall safety is high. The ability to adjust segments postoperatively is advantageous over the use of artificial devices. Limitations include surgeon skill, cost, and tissue availability. AI technology promises to improve accuracy and outcomes. CAIRS is a minimally invasive option for keratoconus and ectatic disease, offering optical and structural benefits. Whether CAIRS will reduce the future role of deep anterior lamellar keratoplasty remains to be determined as direct head-to-head comparative studies between the two procedures are currently lacking. Current evidence supports its use as an effective treatment with the potential for broader adoption as technology advances.