Comparative Evaluation of Scheimpflug Tomography Parameters Between Thin Non-Keratoconic, Subclinical and Mild Keratoconic Corneas

The purpose: This paper aimed to analyze the keratometric, topometric and pachymetric featuresof keratoconic suspect and clinical keratoconic eyes from normal thin ones using a Scheimpflugimaging camera. Patient and methods: The study was retrospective and cross-sectional andexamined the eyes of candidates seeking refractive surgery at Sohag ophthalmologic Centre.The study included 26 normal subjects with 31 eyes with thin corneas (<480 µm), 14 subjectswith 18 eyes diagnosed as keratoconus suspects, and 18 patients with 39 eyes keratoconus (stage1 and 2). The approval of the ethical committee of Sohag University Hospital was acquired.Results: showed that a possible indicator to distinguish between thin corneas and keratoconusgrade 1 & 2 was provided by information on the corneal height, particularly in the case of applyingthe enhanced ectasia presentation. Parameters from BAD display (e.g., anterior, posterior elevationdifferences and final D), topographic parameters (such as Q value, KI, K2, Kmean, Kmax andcylinder), topometric parameters (such as KI, IHD, IVA, IHA, CKI, and ISV values), and pachymetricparameters (such as average PPI and ARTmax) helped discriminate the keratoconus cases with thehighest prediction accuracy. Conclusions: This study shows that these eyes may be discriminatedefficiently using different tomographic (BAD, pachymetry, and elevation) parameters and topometricindices from Pentacam Scheimpflug tomography. It addresses non-keratoconic thin corneas andkeratoconus subclinical or mildly evolved. CT at apex, thinnest CT, IVA, IHD and PE differencestended to be the most appropriate for distinguishing subclinical keratoconic eyes and normal thincorneas