April 2014
Volume 55, Issue 13
Free
ARVO Annual Meeting Abstract  |   April 2014
Estimated corneal elastic moduli from inverse finite element analysis of corneal deformation in vivo
Author Affiliations & Notes
  • Abhijit Sinha Roy
    Ophthalmology, Narayana Nethralaya, Bangalore, India
  • Rohit Shetty
    Ophthalmology, Narayana Nethralaya, Bangalore, India
  • Footnotes
    Commercial Relationships Abhijit Sinha Roy, Cleveland Clinic (P); Rohit Shetty, None
  • Footnotes
    Support None
Investigative Ophthalmology & Visual Science April 2014, Vol.55, 3701. doi:
  • Views
  • Share
  • Tools
    • Alerts
      ×
      This feature is available to authenticated users only.
      Sign In or Create an Account ×
    • Get Citation

      Abhijit Sinha Roy, Rohit Shetty; Estimated corneal elastic moduli from inverse finite element analysis of corneal deformation in vivo. Invest. Ophthalmol. Vis. Sci. 2014;55(13):3701.

      Download citation file:


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

      ×
  • Supplements
Abstract
 
Purpose
 

To develop a patient-specific inverse finite element (iFE) optimization method to estimate the corneal elastic moduli from corneal deformation measured in vivo

 
Methods
 

A subject with a normal cornea was subjected to an air-puff applanation with the Corvis-ST (Oculus Inc., Germany). Corvis-ST only captures images of a cross-section of the cornea. The subject was imaged with Pentacam (Oculus Inc., Germany) A 3-D structure of the cornea and sclera shell was constructed from tomographic measurements (Pentacam, Oculus Inc. Germany). The eye model was supported at four quadrants by structures to approximate the muscles and fat. The transient air-puff pressure was applied on the anterior surface of the cornea. The intraocular pressure was 15 mmHg. For optimization, the coordinates of the deforming anterior edge of the cornea was extracted from the images at different time points. The optimized function was defined as the difference between the displacement of the anterior edge of the cornea estimated by iFE and obtained after image processing of Corvis-ST images. All tissue structures were assumed to be hyperelastic, isotropic and incompressible. The reduced polynomial material model was used for the cornea-sclera shell and support structures, respectively (Abaqus v.6.12, Simulia Inc., USA).

 
Results
 

The estimated material properties (coefficients of reduced polynomial model) were C10=75kPa, and C20=20MPa. Figure 1 shows a comparison of the deformation amplitude of the apex of the cornea measured by Corvis-ST (dots) and estimated by the inverse method (line). The level of agreement is excellent during the pressure increase period. However after around 0.02 sec, there is difference between the estimated and measured displacement. Figure 2 shows a comparison of the displacement of the anterior edge of the cornea measured by Corvis-ST (dots) and estimated by the inverse method at different time (line). At time 0.01 and 0.015, the profiles match very well but at 0.02 sec, differences are evident.

 
Conclusions
 

A novel method of inverse estimation of corneal material properties from in vivo measurements of corneal deformation was developed. The difference in the result after 0.02 sec was most likely due to approximation of the globe structure in the FE model. Future work will focus on incorporation of fiber directions in the cornea and improved estimation of the globe biomechanical response.

  
Keywords: 480 cornea: basic science • 473 computational modeling • 678 refractive surgery  
×
×

This PDF is available to Subscribers Only

Sign in or purchase a subscription to access this content. ×

You must be signed into an individual account to use this feature.

×