Visual, Tomographic, and Biomechanical Outcomes of CAIRS with Accelerated Cross-Linking in Moderate to Advanced...

To evaluate the visual, tomographic, and biomechanical effects of corneal allogenic intrastromal ring segments (CAIRS) combined with accelerated epithelium-off corneal cross-linking (CXL) in patients with moderate to advanced keratoconus.

This retrospective case series included 40 eyes of 40 patients with keratoconus. CAIRS segments were prepared from donor corneal tissue stored in Netisol medium and implanted via femtosecond laser-created intrastromal channels. Accelerated epithelium-off CXL (10 mW/cm² for 9 minutes; total energy 5.4 J/cm²) was performed immediately after CAIRS implantation; an individualized Sub400 protocol was applied in eyes with post-implantation pachymetry below 400 µm. Outcomes at baseline and 6 months included best-corrected visual acuity (BCVA), spherical equivalent, keratometric indices, pachymetry, higher-order aberrations (HOAs), and Corvis ST biomechanical parameters.

Median BCVA improved from 0.52 to 0.22 logMAR (p=0.005), and spherical equivalent improved from -9.3 D to -4.1 D (p=0.007). K1, K2, Km, and Kmax showed statistically significant flattening (all p<0.05). HOAs and coma did not significantly change. SP-A1 decreased from 52.7 to 51.2 mmHg/mm (p=0.015), while integrated radius showed no significant difference. One eye (2.5%) developed donor segment opacification within the first postoperative week without functional visual consequence; BCVA improved in this eye. No rejection, extrusion, or other adverse events were recorded.

CAIRS combined with accelerated CXL demonstrated significant improvements in visual acuity, refractive error, and keratometric parameters at 6 months. These findings suggest that CAIRS may represent a promising biological alternative to synthetic intracorneal ring segments, warranting further investigation through prospective controlled studies with longer follow-up.