Measurements
corneal thickness
ANTERIOR
All measurements are performed in constant, dim-lighting conditions. Several corneal curvature and corneal thickness measurements were obtained from each image by each instrument:Anterior axial power of the flattest meridian (AKf, D)Anterior axial power of the steepest meridian (AKs, D)Posterior axial power of the flattest meridian (PKf, D)Posterior axial power of the steepest meridian (PKs, D)Central corneal thickness (CCT, μm)Thinnest corneal thickness (TCT, μm)Horizontal location of thinnest corneal point (TCP(X, mm), in which 0 indicates the apex, positive value for the temporal direction, and negative value for the nasal direction (TCP(X), mm)Vertical location of thinnest corneal point from apex (TCP(Y), mm), in which 0 indicates the apex, positive value for the superior direction, and negative value for the inferior directionPeripheral corneal thickness at intersection between the 2-mm diameter circle and the nasal horizontal meridian (PCT2, μm)Peripheral corneal thickness at intersection between the 4-mm diameter circle and the nasal horizontal meridian (PCT4, μm)Peripheral corneal thickness at intersection between the 6-mm diameter circle and the nasal horizontal meridian (PCT6, μm)