Variable Complexity Corneal Surfaces Characterization by Modal Geometrical Reconstruction Methods: Comparative Study

Abstract

Validation of new methods for keratoconus diagnosis has generated a great interest for the last years in the field of ophthalmology. Corneal surface reconstruction by discrete 3D points creates the possibility to apply modal or zonal geometrical methods. The goal of this work is to determine the geometrical behavior of the cornea in each keratoconus stage by different modal geometrical models, mainly, those derived from the general equation of the biconical and its associated parameters. This study included a total amount of 75 eyes, 20 of these were healthy eyes and 55 classified with keratoconus pathology by using Amsler-Krumeich classification. After studying the proposed models, the biconical model showed the best fit model while spherical model showed the worst fit one. By assessing geometrical parameters from biconical model, curvature radius and asphericity in the main direction, the geometrical corneal behavior can be assessed in each keratoconus stage in both anterior and posterior cornea. Using a variable reduction in two parameters, mean radius and mean asphericity, a decreasing trend in both parameters with keratoconus progress is found. Therefore, this study proposes to validate the biconical model for variable complexity surfaces with keratoconus pathology as a tool for diagnosis in clinical practice.