Outcomes of keraring implantation for high regular astigmatism in non-ectatic corneas: A prospective pilot case series

This study aimed to evaluate the effectiveness of intracorneal ring segments (Keraring) implantation for the management of high regular astigmatism (> 3.00 D) in eyes with non-ectatic corneas. Twenty eyes of twenty patients with high regular astigmatism and topographically normal corneas. All eyes underwent femtosecond laser-assisted implantation of SI-5 Keraring segments. Comprehensive preoperative and postoperative assessments included uncorrected and best-corrected distant visual acuity, manifest refraction, keratometric measurements, and anterior corneal higher-order aberrations (HOAs). Follow-up examinations were performed at 1 week, 1 month, and 6 months. Statistical analysis incorporated repeated-measures ANOVA and Pearson correlation coefficients. Significant improvement in UDVA was observed at all postoperative visits (p < 0.001). CDVA improved significantly during the early postoperative period but not at 6 months. Mean refractive astigmatism decreased markedly from - 8.19 ± 2.50 D preoperatively to - 3.14 ± 1.55 D at 6 months postoperatively, corresponding to a mean reduction of 61.3% (p < 0.000). Significant reductions were also observed in spherical equivalent, Keratometric indices, total HOAs and coma aberrations. Corneal thickness and spherical aberrations showed no significant changes throughout the follow-up period. No intraoperative or postoperative complications were observed. Keraring implantation may provide meaningful improvements in visual acuity, refractive outcomes, corneal regularity, and selected higher-order aberrations in eyes with high regular astigmatism and non-ectatic corneas. Larger studies with longer follow-up are warranted to confirm these preliminary findings.