Intrastromal corneal ring segment implantation in paracentral keratoconus with coincident topographic and coma axis

Purpose To evaluate the efficacy, predictability, and safety of implantation of Ferrara‐type intrastromal corneal ring segments (ICRS) for refractive correction of paracentral keratoconus. Setting Fernández‐Vega Ophthalmological Institute, Oviedo, Spain. Design Cohort study. Methods Snellen uncorrected (UDVA) and corrected (CDVA) distance visual acuities and residual refractive errors were recorded before and 6 months after ICRS implantation for keratoconus. The tunnels for ICRS implantation were created with a femtosecond laser. The power vector and the Alpins method were used to analyze postoperative refractive outcomes. Results The study evaluated 56 eyes of 49 patients. The mean UDVA was 0.17 ± 0.14 (SD) preoperatively and 0.41 ± 0.28 postoperatively and the mean CDVA, 0.70 ± 0.18 and 0.80 ± 0.17, respectively (both P<.0001). The efficacy index was 0.60. Five eyes lost 1 line of CDVA, 17 eyes had unchanged CDVA, 15 eyes gained 1 line, 9 eyes gained 2 lines, 7 eyes gained 3 lines, and 3 eyes gained 4 lines. The safety index was 1.14. The spherical equivalent and astigmatism were significantly lower postoperatively than preoperatively (P<.01). Of the eyes, 78.6% were within ±1.00 D of the target‐induced astigmatism. No intraoperative or postoperative complications occurred. Conclusion Intrastromal corneal ring segment implantation in eyes with paracentral keratoconus provided good visual and refractive outcomes, indicating that it is a predictable and safe procedure for refractive correction in these cases. Financial Disclosure No author has a financial or proprietary interest in any material or method mentioned.