Keraring® Intracorneal Ring Segments for High Postkeratoplasty Astigmatism: 18 Months Follow-Up

Abstract

Purpose: : The objetive of this study is to assess the safety and efficacy of Keraring^® intracorneal ring segments (Mediphacos Ltda. Belo Horizonte, Brazil), implantation for the correction of high postkeratoplasty astigmatism.

Methods: : In this retrospective noncomparative interventional case series, 9 postkeratoplasty eyes of 9 patients (4 males and 5 females) ages 28 to 79 years (mean age, 50.2 ± 16.7 years) with high astigmatism (above 4 diopters (D)) that had intracorneal ring segment implantation were reviewed.Inclusion criteria were contact lens intolerance,best corrected visual acuity (BCVA) ≤ 0.4,no allograft rejection, penetrating keratoplasty surgery more than 2 years before and suture removal at least 6 months before. Only patients with a minimum follow-up of 12 months were included. Two segments were inserted into the cornea of each eye. BCVA,refractive astigmatism, spherical equivalent (SE),surgically induced astigmatism (SIA),central corneal curvature, topographic corneal astigmatism, surface regularity index (SRI),surface asymmetry index (SAI) and complications were analized.

Results: : Keraring^® segments were successfully implanted in 7 eyes. In two eyes one segment was removed at the surgery time because of their superficial placement. The follow-up ranged from 12 to 22 months (mean: 18 months). The mean BCVA significantly improved from 0.11 ± 0.12 (range, counting fingers-0.4) to 0.62 ± 0.25 (range 0.25-1) (p < 0.01).No eye lost BCVA.The mean SE was reduced from 3.17 ± 5.48 D to 0.12 ± 3.06 D (p=0.34) and the mean refractive astigmatism from 6.16 ± 1.17 D to 4.37 ± 2.43 D (p=0.17). SIA was 3.56 ± 1.36 D. The mean central corneal curvature was reduced from 42.11 ± 2.27 D to 36.77 ± 4.13 D (p< 0.01). The mean topographic corneal astigmatism decreased from 8.35 ± 2.4 D to 5.41 ± 1.86 D (p< 0.01). The mean SRI increased from 1.36 ± 0.29 to 1.63 ± 0.26,(p=0.14), and the SAI increased from 1.47 ± 0.84 to 2.60 ± 1.05, (p=0.05). Only one complication ocurred (one patient developed deep vascularization in the lower temporal stromal channel).

Conclusions: : Implantation of Keraring^® intracorneal ring segments to correct post-keratoplasty astigmatism was effective for reduction of corneal curvature and topographic astigmatism, with a significantly improvement in BVCA. No severe complication ocurred.

Keywords: transplantation • astigmatism • refractive surgery: other technologies