Comparative Effectiveness Of Cairs Versus Icrs In Keratoconus: A Systematic Review And Meta-Regression Analysis
Published 2026 - 44th Congress of the ESCRS
Reference: FP30.06 | Type: Free paper | DOI: 10.82333/sx53-9h50
Authors: A/Prof. Jorge L. Alió del Barrio* 1 , Dr Hao Zhang 1 , Dr Javier H. Gonzalez-Lugo 2 , Dr María Barceló Arenas 3 , Dr Mario Canto-Cerdan 2
1Vissum Grupo Miranza,Alicante,Spain;Division of Ophthalmology,Universidad Miguel Hernández,Alicante,Spain, 2Vissum Grupo Miranza,Alicante,Spain, 3Division of Ophthalmology,Universidad Miguel Hernández,Alicante,Spain
Purpose
To compare the clinical and topographic outcomes of corneal allogenic intrastromal ring segments (CAIRS) and polymethylmethacrylate intrastromal corneal ring segments (ICRS) in keratoconus without concomitant cross-linking.
Setting
Systematic review and meta-analysis
Methods
A systematic review and meta-analysis were conducted including comparative and single-arm studies reporting pre–post outcomes after CAIRS or ICRS implantation. Random-effects models were applied to calculate pooled mean changes. Mixed-effects meta-regression was performed using surgical technique as a moderator (ICRS relative to CAIRS). Primary outcomes included UDVA, CDVA, refractive parameters, keratometry, central corneal thickness (CCT), and higher-order aberrations. Sensitivity analyses were performed under alternative correlation assumptions. Small-study effects were assessed using Egger’s regression.
Results
Twenty-three studies (1,004 eyes: 428 CAIRS; 576 ICRS) were included. Both techniques significantly improved visual acuity and reduced refractive and keratometric parameters. Meta-regression favored CAIRS for CDVA (β=0.19 logMAR, p<0.001), sphere (β=−2.85 D, p<0.001), SE (β=−2.02 D, p=0.003), and flat K (β=2.12 D, p<0.001). ICRS achieved greater astigmatic reduction (β=0.99 D, p=0.007). No differences were observed for UDVA, steep K, mean K, Kmax, CCT, spherical aberration, coma, or total HOAs. Heterogeneity was lower with CAIRS, particularly for keratometric outcomes (I²=0% across multiple outcomes), whereas ICRS showed greater variability in visual and selected topographic endpoints. Sensitivity and influence analyses confirmed robustness
Conclusions
Both CAIRS and ICRS are effective in keratoconus management. However, CAIRS demonstrates superior improvement in corrected visual acuity, spherical refractive error, and corneal flattening, with greater effect homogeneity. ICRS provides stronger cylindrical correction. These findings suggest differential biomechanical and refractive profiles that may inform individualized surgical planning.