Study and characterization of morphogeometric parameters to assist diagnosis of keratoconus

Abstract

Background: In case of signifcant imperfections on the cornea, data acquisition is difcult and a signifcant level of missing data could require the interpolation of important areas of the cornea, resulting in a very ambiguous model. The development of methods to defne in vivo customised geometric properties of the cornea based only on real raw data is extremely useful to diagnose and assess the progression of diseases directly related to the corneal architecture. The present work tries to improve the prognostic of corneal ectasia creating a 3D customised model of the cornea and analysing diferent geometric variables from this model to determine which variables or combination of them could be defned as an indicator of susceptibility to develop keratoconus. Methods: A corneal geometric reconstruction was performed using zonal functions and retrospective Scheimpfug tomography data from 187 eyes of 187 patients. Mor‑ phology of healthy and keratoconic corneas was characterized by means of geometric variables. The performance of these variables as predictors of a new geometric marker was assessed and their correlations were analysed. Results: The more representative variable to classify the corneal anomalies related to keratoconus was posterior apex deviation (area under receiver operating characteris‑ tic curve>0.899; p<0.0001). However, the strongest correlations in both healthy and pathological corneas were provided by the metrics directly related to the thickness, as deviations of the anterior/posterior minimum thickness points. Conclusions: The presented morphogeometric approach based on the analysis and custom geometric modelling of the cornea demonstrates to be useful for the charac‑ terization and diagnosis of keratoconus disease, stating that geometrical deformation is an efective marker of the ectatic disease’s progression.