Intracorneal ring segment implantation in corneas with post-laser in situ keratomileusis keratectasia

Abstract

Purpose: To evaluate the refractive and aberrometric changes in corneas with post-LASIK keratectasia implanted with intracorneal ring segments (ICRS) during a 2-year follow-up. Design: Retrospective, consecutive case series. Participants: Thirty-four eyes of 25 patients (age range, 20–59 years) with post-LASIK ectasia were included. Ectasia was diagnosed by slit-lamp appearance of corneal thinning, unstable topographic steepening, progressive corneal thinning on ultrasonic pachymetry, decreased visual acuity, and unstable refraction. Methods: Intracorneal ring segment implantation was performed in all cases by 2 surgeons from 2 different ophthalmologic centers with the aim of correcting the spherocylindrical error and improving the visual quality. Corneal tunnels were created by means of mechanical dissection in 20 eyes and femtosecond laser technology in 14 eyes. Intacs (Addition Technology, Inc, Fremont, CA) were inserted in 24 eyes, and KeraRings (Mediphacos, Belo Horizonte, Brazil) in 10 eyes. In all cases a follow-up of 12 months was completed, with a total of 15 eyes examined 24 months after surgery. Main Outcome Measures: Uncorrected visual acuity (UCVA), best spectacle-corrected visual acuity (BSCVA), refraction, keratometry, and corneal aberrations. Results: Uncorrected visual acuity did not improve after surgery (P = 0.17). Best spectacle-corrected visual acuity increased significantly at 6 months (P = 0.02). Some 38.89% of eyes gained 2 or more lines of BSCVA at 6 months, and this percentage increased to 60% at 24 months. There was a nonsignificant reduction of sphere at 6 months (P = 0.28). Manifest cylinder was reduced significantly during the postoperative follow-up (P = 0.05, preoperative to 6 months; P = 0.04, 6–12 months). The cornea was on average flatter at 6 months (P<0.01), with a posterior nonsignificant regression of the achieved flattening (P = 0.73). In regard to corneal aberrations, a statistically significant reduction was found in coma-like root mean square (RMS) (P = 0.03) after surgery. Segment ring explantation was performed in 6 eyes, and ring reposition was performed in 2 eyes. The apical curvature gradient was significantly higher in the group of explanted eyes (P = 0.03). Conclusions: Intracorneal ring segment implantation is a useful option for the treatment of coma-like aberrations and astigmatism in post-LASIK corneal ectasia.