Manual, Non-Femto, Corneal Allogenic Intrastromal Ring Segments (Cairs) Using Glycerin-Preserved Cornea: A Prospective Case Series With A Single Donor For Multiple Patients”

To evaluate the short- and mid-term clinical outcomes of a manual technique for customized Corneal Allogenic Intrastromal Ring Segments (CAIRS) using fresh and glycerin-preserved corneas.

A prospective, interventional study

Ten eyes of ten patients with stable keratoconus and BCVA ≤ 20/30 Snellen underwent surgery. CAIRS segments were prepared from fresh corneas, glycerin-preserved corneas, and peripheral rim remnants from previous keratoplasties. Segments were implanted into manually dissected corneal tunnels using corneal dissectors. Postoperative follow-ups occurred at 24 hours, 10 days, 50 days, 3 months, and 8 months with tomographic outcomes assessed at 3 and 8 months.

At 8 months of follow-up, mean keratometry (Km) was significantly reduced by 2.34 ± 2.18 D (p = 0.020), and K2 decreased by 2.83 ± 2.00 D (p = 0.006), confirming effective corneal flattening. Topographic astigmatism showed a significant reduction (p = 0.014), while a non-significant trend toward coma reduction was observed (p = 0.16). Uncorrected visual acuity improved in 70% of eyes, with a mean improvement of 0.35 logMAR. Best-corrected visual acuity improved by a mean of 0.19 logMAR, with 70% of eyes showing line gains. Visual and tomographic improvements were more pronounced at 3 months, with mild changes observed by 8 months, suggesting ongoing corneal remodeling over time.

Manual CAIRS using a single donor cornea for multiple patients, including glycerin-preserved tissue, provides effective visual and topographic improvement. This technique represents a valuable option for keratoconus management in settings with limited corneal availability and without femtosecond laser access.