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Biomechanics of Stabilizing the Keratoconic Cornea

  • Cynthia J. Roberts
Chapter

Abstract

Although characterized by asymmetry in curvature, elevation, and thickness profile, the primary alteration in keratoconus is likely biomechanical, which leads to these secondary geometric changes. The keratoconic cornea is characterized by focal weakening under a uniform intraocular pressure load, which leads to a local increase in strain (stretch) and thinning in the area of pathology. Stress is a function of both curvature and thickness, with low thickness and low curvature associated with greater stress. Therefore, as the cornea thins the stress is redistributed, the curvature increases as a compensatory response. This leads to further thinning and additional increases in curvature. Thus, the initial focal weakening triggers a cycle of biomechanical decompensation and progression. This cycle can be interrupted and the cornea stabilized in two ways. First, stiffening using cornea collagen crosslinking will alter the cycle, with focal stiffening in the area of pathology predicted to reduce the biomechanical asymmetry and generate a greater response than global stiffening. Second, implantation of intracorneal rings immediately alters the curvature pattern and thus the stress distribution, interrupting the cycle of decompensation.

Keywords

Keratoconus Biomechanics Decompensation Weakening Stress Strain Corneal crosslinking Intracorneal rings 

Notes

Disclosures

Oculus Optikgeräte GmbH, Consultant

Optimeyes, Consultant and Advisory Board

Ziemer Ophthalmic Systems AG, Consultant

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Copyright information

© Springer Nature Switzerland AG 2019

Authors and Affiliations

  • Cynthia J. Roberts
    • 1
  1. 1.Martha G. and Milton Staub Chair for Research in Ophthalmology, Professor of Ophthalmology and Vision Science, Professor of Biomedical EngineeringThe Ohio State UniversityColumbusUSA

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