Clinical outcomes of femtosecond laser-assisted corneal allogenic intrastromal ring segment (CAIRS) in the treatment of keratoconus

Background: To evaluate the results of corneal allogenic intrastromal ring segment (CAIRS) implantation in keratoconus. Methods: The medical records of patients with keratoconus who underwent CAIRS implantation were reviewed. The CAIRS, prepared by trephination from the donor cornea, was implanted into a tunnel created using the femtosecond laser. The depth of the tunnel was 200 mu; the inner diameter of the tunnel was 4.5 mm; and the outer diameter was 7 mm. Uncorrected visual acuity (UCVA), best corrected visual acuity (BCVA), keratometry, minimum corneal thickness (CT), endothelial cell density (ECD), and high order aberration values were recorded preoperatively and at the 1st, 3rd, and 6th months postoperatively. Results: A total of 23 eyes of 23 patients were included in the study. Preoperative UCVA (0.08 +/- 0.01) and BCVA (0.25 +/- 0. 11) values improved postoperatively and reached 0.40 +/- 0.05 and 0.68 +/- 0.09, respectively, at the end of the 6-month follow-up period (p(1) < 0.001, p(2) = 0.016; respectively). A statistically significant flattening of all keratometric values was observed in the postoperative period compared to preoperatively (p < 0.001 for all). There were no statistical differences between CT and ECC values at the preoperative and postoperative visits (p(1) = 0.654, p(2) = 0.769; respectively). In addition, coma aberration values were lower than the preoperative values at all postoperative visits (p < 0.05 for all). Conclusions: These results suggest that CAIRS implantation is a safe treatment option with good visual and keratometric outcomes for suitable patients with keratoconus.