EARLY KERATOCONUS DETECTION BY PATIENT-SPECIFIC 3D MODELLING AND GEOMETRIC PARAMETERS ANÁLISIS

Abstract

The purpose of this paper is to assess if the corneal geometric modelling analysis could be useful for detection of early keratoconus (early KC) with normal visual acuity by discriminating from those normal cases. The study included a total of 286 subjects (149 early KC eyes associated to normal vision with mean age of 36.14 ± 10.28 years, and 137 normal eyes with mean age of 34.38 ± 7.02 years). A reconstruction from the raw data of Sirius Scheimpflug-Placido corneal tomography and a posterior analysis of the virtual 3D custom model were performed. The morphogeometric variables extracted from the corneal model were statistically analysed for both studied groups. Finally, receiver operator characteristic (ROC) curves were established to determine their predictive values and accuracy parameters. Thirteen of the fourteen morphogeometric measurements reached significant differences between groups (P < .05). Among the efficiency discrimination by ROC curve, six of the modelled variables obtained an area under the ROC curve over 0.7, these are: sagittal plane apex ar-ea, anterior corneal surface area, sagittal plane area in minimum thickness point, net deviation from centre of mass XY and total corneal volume, where the posterior apex deviation had the greatest area under the ROC curve (area: 0.856, sensitivity: 79.3%, specificity: 78.5%). The analysis of corneal geometric custom modelling demonstrates to be a new and useful tool for the practice of refractive surgery by providing excellent accuracy to detect early corneal deformation in KC patients with normal visual acuity. Keywords: Geometric Modelling, Cornea Reconstruction, Diagnosis, Scheimpflug, Computer-Aided Design