Comparison of clinical outcomes between manual and femtosecond laser techniques for intrastromal corneal ring segment implantation

Purpose: The purpose was to compare the visual, refractive and aberrometric results of intrastromal corneal ring segments implantation with manual dissection and femtosecond laser–assisted surgery. Methods: This is a multicentre study, which included consecutive patients with paracentral keratoconus, in which the difference between the axes of the topographic flattest and the coma aberration was <60°, who had Ferrara-type intrastromal corneal ring segment implantation using manual dissection or femtosecond laser technique. LogMAR uncorrected (uncorrected distance visual acuity) and corrected (corrected distance visual acuity) distance visual acuity, refractive errors and the root mean square for corneal coma-like aberration were recorded before and at 6 months after surgery. Results: The study included 84 and 110 eyes in the manual group and in the femtosecond group, respectively. After surgery, there was a statistically significant improvement in uncorrected distance visual acuity and corrected distance visual acuity for both groups (p < 0.0001), and there were no statistically significant differences between groups (p > 0.3). For both groups, there was a reduction in spherical equivalent after intrastromal corneal ring segment implantation (p < 0.0001). There were no statistically significant differences between groups in the magnitude of spherical equivalent reduction (p = 0.34) The magnitude of the root mean square coma-like reduction was 0.93 ± 0.76 and 0.83 ± 0.80 μm in the manual and femtosecond group, respectively (p = 0.2). While in the femtosecond laser group no complications were reported, in the manual group, the intraoperative or postoperative complications rate was 13.09%. Conclusion: Although both surgical techniques provide comparable visual, refractive and aberrometric outcomes, it should be noted that the femtosecond laser is a safer surgical procedure, with no complications reported.