Investigation of the efficiency of intrastromal ring segments with cross-linking using different sequence and timing for keratoconus.

Aim: To evaluate and compare the efficacy and stability of intrastromal corneal ring segment (ICRs) implantation with cross-linking (CXL) using different sequence and timing.

Methods: In this single retrospective study, 86 keratoconic eyes subjected the ICRs implantation. We analyzed only 41 eyes that had complete follow-ups. They were divided into three groups: ICRs implantation was applied only (group normal), ICRs first followed by CXL immediately (group CXL-S), CXL first followed by ICRs long after (group CXL-B). The visual acuity, refractive results, keratometry were compared preoperatively and 1y postoperatively. Their differences among the three groups were also analyzed.

Results: Group normal comprised 25 eyes, group CXL-S 8 eyes, and group CXL-B 8 eyes. There were improvements in the mean uncorrected distance visual acuity (UDVA) and the mean corrected distance visual acuity (CDVA) compared preoperatively and 1y postoperatively {UDVA: 0.31 (P=0.030) logarithmic minimum angle of resolution [logMAR] group normal, 0.4 (P=0.020) group CXL-S, 0.45 (P=0.001) group CXL-B; CDVA: 0.21 logMAR (P=0.013) group normal, 0.30 (P=0.036) group CXL-S; 0.26 (P=0.000) group CXL-B}. The refractive and topographic outcomes also showed improvements. In terms of comparisons among the three groups, all the P values were above 0.05, showing no significant difference. But only group CXL-B had improvement in UDVA and CDVA for all the patients.

Conclusion: With safety and good visual outcomes, ICRs implantation is a viable alternative for keratoconus. No significant difference was found among these three groups.