Clinical outcomes after intracorneal ring segment implantation for keratoconus management in thin corneas.

Abstract

Purpose : Intracorneal ring segment (ICRS) implantation is currently performed for visual improvement in patients with keratoconus whose thinnest corneal pachymetry is above 400 microns. The aim of this retrospective cohort study was to evaluate the clinical outcomes after ICRS implantation for keratoconus in patients with thin corneas.

Methods : Ten eyes from 10 patients with keratoconus, who underwent femtosecond laser-assisted ICRS implantation for keratoconus, were included in this study. Patients had keratoconus stage 2 or 3 according to Amsler-Krumeich classification and have had corneal crosslinking in the past. They all had contact lens intolerance. All eyes included in the study, showed thinnest corneal pachymetry less than 400 microns. Uncorrected visual acuity (UCVA), corrected visual acuity (CDVA), spherical equivalent (SE) corneal astigmatism, Kmax, Kmean, central corneal thickness and thinnest corneal pachymetry have been evaluated preoperatively and 6 months after the Keraring implantation. Paired t-test was applied for statistical analysis. P values less than 0.05 were considered statistically significant.

Results : Ten eyes of 10 patients (8 males and 2 females) were included in the study. Mean age (years) was 34.1±7.8. UCVA (logMAR) and CDVA (logMAR) improved significantly from 0.91±0.07 and 0.4±0.25 preoperatively to 0.71±0.15 and 0.2±0.18 at 6 months postoperatively, respectively (all p<0.05). SE (diopters) and corneal astigmatism (diopters) significantly decreased from -12.8±5.1 and -7.3±2.4 preoperatively to -6.42±4.11 and -3.25±-2.25 at 6 months postoperatively, respectively (all p<0.05). Kmax (diopters) and Kmean (diopters) also decreased from 66.9±6.9 and 53.2±4.4 preoperatively to 57.78±7.74 and 48.53±5.83 postoperatively, respectively (all p<0.05). Changes in central corneal thickness and thinnest corneal pachymetry were not statistically significant (all p>0.05). No complications occurred peri- or postoperatively.

Conclusions : Our study showed significant keratometric amelioration and visual improvement after ICRS implantation for keratoconus in patients with thin corneas at 6 months postoperatively. Therefore, we believe that the corneal thickness threshold of 400 microns should not represent an absolute inclusion criterion for indicating ICRS implantation in patients with keratoconus.

This is an abstract that was submitted for the 2018 ARVO Annual Meeting, held in Honolulu, Hawaii, April 29 - May 3, 2018.