A practical and efficient technique for corneal allogenic ring segment implantation: prolene suture-guided insertion

To describe a practical and efficient prolene suture-guided technique for corneal allogenic intrastromal ring segment (CAIRS) implantation and to evaluate intraoperative difficulties and complications associated with the procedure. Medical records and surgical videos of patients who underwent CAIRS for keratoconus were retrospectively reviewed. All procedures were performed by the same surgeon using standardized femtosecond laser parameters. Donor stromal rings were prepared from residual corneal tissue obtained during keratoplasty procedures. A 5-0 prolene suture was passed from the Bowman's layer toward the endothelial side to guide ring insertion through a narrow stromal tunnel. Intraoperative challenges, including suture disengagement and tunnel-related issues, were documented and analyzed. Twenty-three eyes of 23 patients were included. Combined CAIRS and collagen cross-linking (CXL) were performed in 78.3% of patients. The median ring width was 1.5 mm, and femtosecond-created tunnels had a median inner diameter of 4.8 mm and outer diameter of 7.8 mm. Intraoperative complications occurred in 4 cases (17.4%), all due to prolene suture disengagement. No statistically significant association was found between these events and surgical parameters. Re-passing the suture from the Bowman's side reliably restored secure guidance and enabled successful implantation in all cases. In all cases, the surgery was successfully completed under prolene suture guidance. CAIRS is a minimally invasive and customizable treatment option for corneal ectasia. The prolene suture-guided technique described in this study may facilitate graft implantation, which is one of the most technically challenging steps of the procedure, by enabling the placement of relatively wide allogenic segments into stromal tunnels without the need for graft dehydration. This approach appears to be a practical and reproducible refinement in CAIRS surgery.