## 3 Results and Discussion  
The stress distributions in the measurement phase with the displacement and prestress method are observed in Figures 4-6 for the three analyzed corneas. In all the studied cases, the stress distribution and maximum values obtained were similar with the two implemented methods. Differences between corneal models, Navarro, G0 and G1, are due to the geometrical and thickness variation and the level of intraocular pressure considered (15 mmHg for Navarro model, 18 mmHg for G0 model, and 16 mmHg for G1). The theoretical model showed a symmetric distribution that could be evaluated in a quarter finite element model however in patient-specific models' thickness and geometry are not symmetric and the whole model must be taken into account. For the Navarro theoretical model, maximum values are obtained in the posterior limbus zone where displacements are constrained, and fibers are oriented circumferentially (Figure 4). In this zone, as was observed with X-ray scattering [21] high fibers' density was located. Excluding the limbus zone, the stress distribution in the posterior zone showed a concentric distribution with a stress increment in the center. These results are coherent with the results of other works [21] and could explain the different lamellae's dimensions in the corneal thickness where lamellae are twice as thick in the posterior zone compared to anterior one. In the anterior zone, the results were more homogeneous with lighter stress steps due to the definition of sectors. The obtained von Mises stress level is lower than in the posterior zone and this factor could explain the difference in lamellae thickness, which was thicker in the posterior zone [21]. Figure 4: Stress distribution in measurement phase for Navarro’s Geometry. Displacement method (**Upper**), prestress method (**Lower**). The values obtained and spatial distribution are similar to those obtained by [PERSON] and [PERSON] [35]. However, these authors only use theoretical geometries, whereas in the current research real patient-specific geometries were used besides a theoretical geometry. For patient-specific models (Figures 5 and 6), the stress distribution obtained with the implemented biomechanical models was coherent with the fibers' orientation and density observed by X-ray scattering [22]. An increase was noted for the fibers oriented in the superior-inferior and nasal-temporal directions in the central zone, which continued in a central zone of approximately 7 mm in diameter [24]. These results are consistent with those obtained on the theoretical geometric model by other authors [28; 29; 34], however, our models, in addition to the theoretical model, are applied on real cases of healthy and sick patients (G0 and G1, respectively). Figure 5: Stress distribution in measurement phase for cornea G0. Displacement method (**Upper**), prestress method (**Lower**). Figure 6: Stress distribution in measurement phase for cornea G1. Displacement method (**Upper**), Prestress method (**Lower**). The X-ray images confirmed an increment in fiber density in the internal zone of the limbus, which coincided with the zone where the von Mises stress level rose. The maximum values were obtained in the limbus zone for G0 configuration, but these values were affected by the intraocular pressure (IOP) considered in the study and the constraints imposed in these zones when displacements were constrained. These restrictions are common for this type of study [28; 29; 34]. An average maximum value was obtained in the central zone for the three analyzed geometries, as shown in Table 2. These values are affected by the IOP in the measurement phase (patient-specific). By means of a linear interpolation and by taking a reference intraocular pressure of 15 mmHg, the maximum values of the von Mises stress distribution in the measurement phase were obtained.