Use of Preexisting ICRS Tunnels for Implantation of CAIRS Following ICRS Migration and Corneal Tissue Necrosis: A Case Report.

To present a case of synthetic intrastromal corneal ring segment (ICRS) intrusion secondary to necrosis and migration, managed by implantation of corneal allogenic intrastromal ring segments (CAIRS) within the preexisting tunnel. A 24-year-old man with known keratoconus underwent bilateral ICRS implantation. He presented with blurred vision in the right eye 6 weeks after the procedure. The patient developed segment intrusion secondary to migration and necrosis. The synthetic ring was subsequently explanted, and a CAIRS was inserted into the same corneal tunnel. Postoperative assessment showed significant visual improvement. The patient's spectacle corrected distance visual acuity (CDVA) improved from 20/60 to 20/25, his astigmatism reduced from -6.50 to -4.00 diopters (D), and his keratometry readings decreased from 49.00 to 45.00 D. The CAIRS remained stable, fully filling the stromal defect and covering the area of intrusion, with no signs of necrosis or migration at the 6-month follow-up visit. CAIRS are a safe and effective alternative for addressing complications arising from synthetic ICRS in patients with keratoconus, offering improved visual and topographic outcomes while minimizing risks. Furthermore, it is possible to implant CAIRS within an existing tunnel.