Customized Finite Element Modelling of the Human Cornea.

Irene Simonini,Anna Pandolfi,Alexander V Ljubimov

doi:10.1371/journal.pone.0130426

Abstract

AimTo construct patient-specific solid models of human cornea from ocular topographer data, to increase the accuracy of the biomechanical and optical estimate of the changes in refractive power and stress caused by photorefractive keratectomy (PRK).MethodCorneal elevation maps of five human eyes were taken with a rotating Scheimpflug camera combined with a Placido disk before and after refractive surgery. Patient-specific solid models were created and discretized in finite elements to estimate the corneal strain and stress fields in preoperative and postoperative configurations and derive the refractive parameters of the cornea.ResultsPatient-specific geometrical models of the cornea allow for the creation of personalized refractive maps at different levels of IOP. Thinned postoperative corneas show a higher stress gradient across the thickness and higher sensitivity of all geometrical and refractive parameters to the fluctuation of the IOP.ConclusionPatient-specific numerical models of the cornea can provide accurate quantitative information on the refractive properties of the cornea under different levels of IOP and describe the change of the stress state of the cornea due to refractive surgery (PRK). Patient-specific models can be used as indicators of feasibility before performing the surgery.

Highlights

The growing demand for permanent refractive corrections and laser surgical procedures, such as photorefractive keratectomy (PRK) and LASIK, has increased the importance of corneal topography data in both clinical and research settings.Within the past 10 years, corneal topographers have been converted from elaborate and costly devices used exclusively for clinical research to in-office tools that optometrists use daily
Patient-specific geometrical models of the cornea allow for the creation of personalized refractive maps at different levels of intraocular pressure (IOP)
For the sake of convenience, we used our model of the fibril distribution and a material model developed in our group because of the awareness of the features of the code and the large variety of output data

Summary

Method

Corneal elevation maps of five human eyes were taken with a rotating Scheimpflug camera combined with a Placido disk before and after refractive surgery. Patient-specific solid models were created and discretized in finite elements to estimate the corneal strain and stress fields in preoperative and postoperative configurations and derive the refractive parameters of the cornea. Cedars-Sinai Medical Center; UCLA School of Medicine, UNITED STATES. Data Availability Statement: All relevant data are within the paper and its Supporting Information files.

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