June 2022
Volume 63, Issue 7
Open Access
ARVO Annual Meeting Abstract  |   June 2022
Localized refractive changes induced by a new asymmetric intracorneal ring segment: a 3D Finite-element simulation
Author Affiliations & Notes
  • Sabine Kling
    ITET, Eidgenossische Technische Hochschule Zurich, Zurich, Zürich, Switzerland
    ARTORG, Universitat Bern, Bern, Bern, Switzerland
  • Gonzalo García de Oteyza
    1Clínica Oftalmológica García de Oteyza, Spain
  • Juan Álvarez de Toledo
    3Centro de Oftalmología Barraquer, Spain
  • Rafael I Barraquer
    3Centro de Oftalmología Barraquer, Spain
  • Footnotes
    Commercial Relationships   Sabine Kling Mediphacos; Heidelberg Engineering, Code F (Financial Support); Gonzalo García de Oteyza None; Juan Álvarez de Toledo None; Rafael Barraquer None
  • Footnotes
    Support  Swiss National Science Foundation (Ambizione PZ00P2)
Investigative Ophthalmology & Visual Science June 2022, Vol.63, 4090 – F0054. doi:
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      Sabine Kling, Gonzalo García de Oteyza, Juan Álvarez de Toledo, Rafael I Barraquer; Localized refractive changes induced by a new asymmetric intracorneal ring segment: a 3D Finite-element simulation. Invest. Ophthalmol. Vis. Sci. 2022;63(7):4090 – F0054.

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      © ARVO (1962-2015); The Authors (2016-present)

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Abstract

Purpose : To report the localized changes induced by an asymmetric intracorneal ring segment (ICRS) with varying base width and ring thickness in a finite-element simulation.

Methods : A 3D finite element model (FEM) was developed to simulate both a healthy and a keratoconic cornea. After creating a tunnel at 70% depth of corneal thickness, the displacements corresponding to the insertion of an ICRS of 160° arc length were enforced. Different ICRS designs were studied: (i) an asymmetric ICRS with increasing thickness (150 to 300 mm) and base width (600 to 800 mm) from one end to the other, and (ii) a symmetric ICRS with constant thickness (150, 225 or 300mm) and base width (600, 700, or 800mm) at all angular positions. The deformed geometry was assessed in terms of global curvature, sagittal curvature and optical aberrations; induced strains were assessed qualitatively.

Results : The asymmetric ICRS simulated implantation did correct vertical coma (-12.09 vs -8.34 mm), primary spherical aberration (12.98 vs 12.64 mm) and defocus (8.80 vs 8.29 mm) better than the simulated implantation of symmetric ICRS. Global curvature changes were dominated by ICRS thickness and less influenced by ICRS symmetry. Sagittal curvature showed a pattern of locally restricted flattening interior to the ring and local steepening on the opposite half of the cornea, which was more pronounced in the healthy than in the keratoconic cornea.

Conclusions : This study positions the asymmetric ICRS implantation as the most powerful vertical coma corrector. Correcting optical aberrations by ring design has the potential to prevent poor and disappointing results of ICRS surgery in asymmetric keratoconic phenotypes.

This abstract was presented at the 2022 ARVO Annual Meeting, held in Denver, CO, May 1-4, 2022, and virtually.

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