Femto-Second Laser Created Corneal Allogenic Intrastromal Ring Segments (Cairs)

To report on the outcomes of Femto-second laser created CAIRS surgeries for keratoconus and post-LASIK ectasia.

Private practice with single surgeon.

CAIRS surgery was performed on one eye of patients with diagnosed keratoconus or post-LASIK ectasia. CARIS were created using the Alcon Wavelight FS200 Femtosecond laser and manually inserted into a channel which was created in the recipient cornea using the FS200. The depth of the channel was 50-60% of the corneal thickness. In eyes that required collagen cross-linking, this was performed either immediately following the CAIRS procedure, or 1-3 months later. At 3 months post-op, UDVA, CDVA, Subjective refraction, and corneal tomography were measured.

A total of 17 eyes underwent CAIRS between March 2021 and December 2022. Mean follow-up time was 114 ± 36 days. On average, KMax decreased by 3.3 ± 5.1D, with a maximum flattening of 18.6D. Spherical equivalent reduced by 3.78 ± 6.59D, and cylinder by 2.45 ± 3.48D. The maximum reduction in refractive cylinder was 9.50D. CDVA improved by an average of 0.2 ± 0.2 logMAR, and UDVA by 0.3 ± 0.3 logMAR. The maximum improvements in CDVA and UDVA were 0.7 logMAR and 0.6 logMAR, respectively. No significant complications were recorded.

CAIRS is a safe and effective procedure for the treatment of keratoconus with promising early post-operative outcomes, including significant corneal flattening, reduced refractive cylinder, and improved visual acuity. Future research is needed to determine an appropriate nomogram for segment specifications.