Refractive, Tomographic and Biomechanical Outcomes after Implantation of Ferrara ICRS in Keratoconus Patients

Abstract

Background: Nowadays, ICRS are a step in the treatment of keratoconus. The purpose of this study was to evaluate the refractive effect and the tomographic and biomechanical parameters in keratoconus patients implanted with Ferrara ICRS, and their stability after 18 months. Materials and methods:Twenty eyes of 20 keratoconus patients implanted with ICRS were evaluated. The average follow-up was 18 months. UDVA, CDVA, biomicroscopy, tomography (Pentacam) and biomechanics (ORA) of the cornea were evaluated before and after surgery. For the comparison of groups, the Wilcoxon test was used. Results:The mean UDVA improved from 1.00 to 0.30 and the mean CDVA improved from 0.51 to 0.12; both were statistically significant (p = 0.0001). The average keratometry decreased from 50.7D to 47.5D (p = 0.0003), and the average astigmatism decreased from 5.5D to 3.5D (p = 0.0058). The mean CCT did not change significantly after surgery, but the mean TPP increased from 441.2 to 455.2 µm (p = 0.004). There was a significant reduction in the anterior cornea elevation, both the central (from 16.2-8.8; p = 0.0066) and the minimum (from -43.2 to -57.1; p = 0.0228). No significant change was found for posterior corneal elevation and for biomechanical parameters (hysteresis or CRF). Discussion:There was a significant improvement of UDVA and CDVA after ICRS implantation, in keratoconic eyes. There was a significant and stable corneal flattening, and a decrease of the astigmatism. Corneal biomechanic parameters did not change.

Tomographic Findings After Implantation of Ferrara Intrastromal Corneal Ring Segments in Keratoconus

“…On the other hand, the current study revealed a decrease in the apex and at the thinnest point, as well as a decrease in the maximum elevation inside the 4-mm zone. Sögütlü et al 2 and Salgado-Borges et al 13 found similar results.…”

“…Average K readings decreased from 51.83 ± 6.87 to 47.66 ± 6.08 D (P < .001). Rho et al, 1 Söglütü et al, 2 and Salgado-Borges et al 13 found similar postoperative results: 51.80 ± 4.68 to 49.59 ± 3.71 (P < .001), 50.94 ± 5.01 to 47.78 ± 4.00 (P < .01), and 50.7 ± 4.2 to 47.5 ± 3.7 (P = .0003) D, respectively. We found a decrease from 48.6295 ± 4.2837 D preoperatively to 46.3882 ± 3.6654 D postoperatively (P < .0001).…”

“…Rho et al 1 assessed anterior elevation of the cornea at the central and thinnest points and found a reduction from 36.88 ± 20.63 to 30.44 ± 12.52 (P < .010) and 36.88 ± 20.63 to 30.44 ± 12.52 (P < .010), respectively. Sögütlü et al 13 studied only the anterior maximum elevation, and Salgado-Borges et al 5 investigated the anterior elevation of the center point and the anterior minimum elevation. Both studies showed a statistically significant In the current study, elevation readings in the center of the cornea and at the thinnest point were assessed, as well as the maximum elevation inside the 4-mm central zone.…”

Corneal Biomechanical Properties in Different Ocular Conditions and New Measurement Techniques

“…No significant differences were found in CH in the short-term (<3rd month) postoperative period [ 104 – 106 ] which may indicate that the ICRS alter corneal curvature without changing the viscoelastic response of the corneal tissue. A study conducted on 20 patients with keratoconus showed a stable corneal flattening and a decrease of the astigmatism with no statistically significant changes in ORA parameters, 18 months after ICRS implantation [ 107 ]. Better visual outcomes could be expected for corneas with lower biomechanical corneal resistance due to easier deformation by the ring implantation.…”

Unilateral Post-LASIK Ectasia in a Topographical Normal Eye with a Slight Asymmetry in the Contralateral Eye

“…[14][15][16][17] Recent studies have reported their effective use for the treatment of keratoconus and ectasia resulting from keratorefractive surgery. 18 Treatment with intrastromal rings does not eliminate the progression of keratoconus, but it may delay a corneal transplant procedure.…”