Delaying Deep Anterior Lamellar Keratoplasty: Visual Rehabilitation With Cairs In Grade Iv Keratoconus.

To describe the surgical technique and early visual and tomographic outcomes of corneal allogenic intrastromal ring segments (CAIRS) implantation in a patient with advanced grade IV keratoconus previously treated with corneal cross-linking. This report aims to highlight CAIRS as a viable therapeutic option in cases traditionally considered beyond the indications for synthetic intracorneal ring segments.

Tertiary referral center specialized in cornea and refractive surgery. Hospital Asociación Para Evitar la Ceguera en Mexico.

A 25-year-old patient with bilateral grade IV keratoconus and prior corneal cross-linking underwent CAIRS implantation in the right eye. Femtosecond laser-assisted intrastromal tunnel creation was performed, followed by manual preparation of allogenic corneal ring segments from tectonic donor tissue. Based on a snowman topographic phenotype, two segments were implanted centered in the flattest meridian. Preoperative and postoperative assessments included visual acuity, refraction, corneal OCT, slit-lamp examination, and corneal topography.

Preoperatively, uncorrected visual acuity was counting fingers at 2 meters, improving to 20/400 with pinhole. Corrected distance visual acuity in the treated eye was 20/70, with significant corneal steepening (Km 67.79 D) and marked irregularity. One day postoperatively, uncorrected visual acuity improved to 20/80, reaching 20/40 with pinhole. Tomography demonstrated a substantial reduction in keratometric values (Km 50.49 D) with evident corneal regularization. At one week, uncorrected visual acuity was 20/150, improving to 20/40 with pinhole, while Km remained stable at 51.41 D. These objective improvements were accompanied by high patient-reported visual satisfaction.

CAIRS use donor corneal tissue instead of synthetic material and achieved significant corneal flattening, regularization, and rapid visual improvement with early stability, supporting their role as an effective option in advanced or irregular keratoconus where conventional ring segments may be contraindicated