Posters

Theoretical explanation of tomographic parameters of keratoconus corneas

Poster Details

First Author: M.Jankov SERBIA

Co Author(s):    T. Seiler   T. Koller   H. Studer   T. Seiler           

Abstract Details

Purpose:

To verify finite element modelling (FEM) for the simulation of keratoconus (KCN) and pellucid marginal degeneration (PMD).

Setting:

Institut für Refraktive und Ophthalmo-Chirurgie (IROC), Zürich, Switzerland

Methods:

Corneal Scheimpflug-tomographies (Pentacam, Oculus, Germany) of 200 eyes with manifest KCN/PMD were classified for the eccentricity of the maximum posterior elevation. Categorization of eccentricity was performed in 0.5mm steps ranging from 0 mm for central KCN to 4 mm for PMD. For each group keratometric astigmatism, corneal wavefront calculated 2nd and 4th order Astigmatism, 3rd order Coma, and 4th order Spherical aberration were analyzed and every parameter was fit in functions of eccentricity. The resulting functions were compared to the aberrations of FEM-simulations for keratectasia ranging from central KCN to PMD.

Results:

ratometric astigmatism, 2nd and 4th order Astigmatism, 3rd order Coma, and 4th order Spherical aberration as functions of eccentricity of the maximum posterior elevation correlated well with the simulations within the inner 8 mm of the cornea (p<0.05). However, outside the central 8 mm the simulation did not agree with the clinical data.

Conclusions:

Tomographic patterns ranging from central KCN to PMD in a smooth transition may be explained by focal weakening of the cornea at different eccentricities.

Financial Disclosure:

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