Simulating corneal ectasia using FEM and clinical verification

Session Details

Session Title: Cornea & Miscellaneous
Session Date/Time: Saturday 22/02/2020 | 08:30-11:10
Paper Time: 08:42
Venue: Auditorium des Ministres.

First Author: T.Seiler SWITZERLAND
Co Author(s): E. Businaro  M. Jankov  F. Turgut  B. Früh  H. Studer     

Abstract Details

Purpose:

To simulate keratoconus (KCN) and pellucid marginal degeneration (PMD) using finite element modelling (FEM) and compare the model to clinical tomographies.

Setting:

Dept. of Ophthalmology, Inselspital Bern

Methods:

FEM simulated a focal weakening of the elastic modulus (20 to 65%) and pachymetry (20%) at eccentricities ranging from 0 to 4mm. Simulated corneal tomographies were analyzed for aberrations using Zernike polynomials. Clinical Scheimpflug-tomographies of 321 eyes with KCN and PMD were classified regarding eccentricity of the maximum posterior elevation and compared with the simulations. Statistical comparison was performed for astigmatic and spherical aberration, and coma of 1st order.

Results:

Astigmatism, coma and spherical aberration as functions of eccentricity of the maximum posterior elevation correlated well with the simulations within the central 6mm of the cornea (p<0.05). Spherical aberrations were highest in central KCN, coma predominant in mid-peripheral ectasia and the astigmatic component was increasing with eccentricity of the ectasia. In the periphery of the cornea the simulations were not coincident with the clinical values indicating limits of FEM. The simulated topographical pattern changed from central KCN to KCN to PMD when the eccentricity of the elastic modulus minimum increased from 0 to 4mm.

Conclusions:

There is a smooth transition from central KCN to PMD while the focal weakening of the cornea varies from central to periphery.

Financial Disclosure:

... is employed by a for-profit company with an interest in the subject of the presentation