Corneal Allogenic Intrastromal Ring Segments (Cairs) Versus Topoguided Photorefractive Keratectomy (Tg-Prk): A Comparative Analysis Using Propensity Score Matching

To evaluate the refractive, keratometic and aberrometric outcomes after corneal allogenic intrastromal ring segment (CAIRS) versus topoguided photorefractive keratectomy (TG-PRK) for matched keratoconus patients.

Department of Ophthalmology, Specialized Medical Center, Riyadh, Saudi Arabia

In this retrospective cohort study, 50 eyes with CAIRS were matched to 50 eyes with TG-PRK using the propensity score matching technique. Each group was matched on a one-to-one basis using multiple parameters such as age, gender, maximum keratometry, central corneal thickness and spherical equivalent. Visual, refractive, topographic, and aberrometric data were measured at baseline, 1 week, 1 month, 3 months, and 1 year postoperatively.

Preoperative parameters were similar between the two groups. Both groups showed significant improvement in best corrected visual acuity (BCVA) (0.25 ± 0.13 to 0.75 ± 0.18 decimel; 0.32 ± 0.27 to 0.77 ± 0.21 decimel, maximum anterior keratometry (62.0 ± 4.3 to 52.2 ± 5.6 D; 56.5 ± 3.8 to 43.2 ± 4.0 D), and vertical coma (1.2 ± 0.8 to 0.6 ± 0.55 D; 0.9 ± 0.65 to 0.4 ± 0.57 D) for CAIRS and TG-PRK, respectively. The improvements observed in both groups at the last follow-up visit were comparable; however, the CAIRS group demonstrated a higher percentage of eyes gaining two or more Snellen lines of BCVA (72% vs 43.5%) in advanced keratoconus, and a greater magnitude of reduction in vertical coma compared to the TG-PRK group.

Both CAIRS and TG-PRK demonstrated similar visual, refractive, topographic, and aberrometric outcomes in mild to moderate keratoconus. CAIRS might be more effective for eyes with more irregular astigmatism and worse BCVA.