Corneal Allogenic Intrastromal Ring Segments: A Literature Review

Corneal allogenic intrastromal ring segments (CAIRSs) offer a novel, biocompatible alternative to synthetic intracorneal ring segments (ICRSs). This review aims to evaluate the clinical outcomes of CAIRS. 

Sussex Eye Hospital, University Hospitals Sussex NHS Foundation Trust, Brighton, United Kingdom.

Inclusion criteria were studies with a minimum of 20 eyes and six months of follow up. The primary outcome measure was uncorrected distance visual acuity (UDVA). The secondary outcomes were a change in corrected distance visual acuity (CDVA), spherical equivalent (SE), mean keratometry (K-mean), maximum keratometry (K-max), K1, K2, and pachymetry. 

The primary outcome UDVA improved from 0.83 ± 0.15 to 0.40 ± 0.08 logMAR (p = 0.01), while CDVA improved from 0.52 ± 0.22 to 0.19 ± 0.09 logMAR (p = 0.01). K-max decreased from 57.8 ± 1.09 D to 53.57 ± 2.66 D (p < 0.01), and K-mean reduced from 49.27 ± 0.28 D to 45.30 ± 1.46 D (p < 0.01). An average of 84.92% ± 11.4% of eyes had an improvement in UDVA. No major complications or significant visual acuity deterioration were reported. 

CAIRSs serve as an alternative to synthetic ICRSs and even corneal transplantation in some cases. They represent a safe, effective, and biocompatible promising advancement in corneal ectasia management to improve visual acuity and corneal topography with minimal complications.