Femtosecond laser–assisted intrastromal corneal ring segment implantation for high astigmatism correction after penetrating keratoplasty

Abstract

To assess the visual and refractive outcomes of femtosecond laser-assisted implantation of Ferrara-type intrastromal corneal ring segments (ICRS) in post-penetrating keratoplasty (PKP) eyes. Instituto Oftalmológico Fernández-Vega, Oviedo, Spain. Cohort study. Patients with previous PKP had ICRS implantation after femtosecond laser tunnel creation. The uncorrected (UDVA) and corrected (CDVA) distance visual acuities and residual refractive errors were recorded before and 6 months after ICRS implantation. The power vector method was used to analyze refractive errors preoperatively and postoperatively. This study enrolled 32 eyes of 30 patients. The mean UDVA (Snellen decimal) changed from 0.16 ± 0.15 (SD) preoperatively to 0.43 ± 0.28 postoperatively (P<.0001). Postoperatively, the UDVA was 20/40 or better in 40.6% of eyes. The mean CDVA was 0.67 ± 0.22 preoperatively and 0.80 ± 0.19 postoperatively (P<.0001). Postoperatively, the CDVA was better than 20/40 in 96.9% of eyes and 20/25 or better in 56.2% of eyes. By 6 months postoperatively, no eye had lost more than 2 lines of CDVA, 4 eyes lost 1 line, 6 eyes had no change, 9 eyes gained 1 line, and 13 eyes gained 2 or more lines. The safety index at 6 months was 1.20. The spherical equivalent and astigmatism components were significantly reduced after ICRS implantation (P<.04). Intrastromal corneal ring segment implantation using the femtosecond laser may be a good alternative for high astigmatism correction in post-PKP eyes.