# Biomechanical Study of the Eye with Keratoconus-Type
## 4 Discussion

Table 3: Corneal curve registered on the nodes of the model for the three levels of severity. This paper presents three finite element models of the eye with keratoconus-type corneal ectasias by level of severity. The first model analyzed a normal eye, the second an eye with corneal ectasia of the keratoconus type, and the third model with the keratoglobus type. When the principal maximum stress exceeded \(3.25\times 10^{-7}\)[36], the presence of keratoconus was obtained but without indication of the level. In the keratoconus model, the main maximum stress was located in the upper temporal area. With an active keratoglobus, control of the main maximum stress was lost, which could become a surgical procedure. The main routine maximum stress with keratoconus-type corneal ectasia is \(3.82\times 10^{-7}\) GPa [36], and this value is smaller than the reported stresses in this paper (\(3.17\times 10^{-6}\) GPa; Figure 9). This indicates that the non-concordance of values may be due to the geographical location of the patient. Researchers in [37] reported that cases of flat corneas (20.00 D to 41.50 D) have been present since the beginning of the last century and are linked to genetic alterations; therefore, it is essential to find adequate methods to diagnose these pathologies. According to a corneal topographer investigating corneal curves [38], the topographic image of a clinical case of corneal curvature shows a small-diameter ectasia, which is better defined in the left eye. For such cases, it would have been convenient to spend more time without glasses, but the patients' vision without glasses was too low. In the topographic image, curvature values were found in the central area close to 63.00 D and 300 mm of curvature [39; 40]. \begin{table}
\begin{tabular}{c c c c c c} \hline \hline
**Authors** & **Clinical Symptoms** & **Diagnostic Process** & **Treatment Modalities** & **Outcomes** & **Ref.** \\ \hline Ours (2023) & Patients in anonymous conditions, their year of birth is known, no gender information or more data can be more data can be was carried out with 3D modeling, with a subsequent finite element analysis. & & The results were as follows in terms of light care. Keratoconus light care. Keratoconus & \(1.07\times 10^{1}\), Keratoconus: \(4.04\times 10^{1}\), Keratoconus: \(5.41\times 10^{1}\). While in many main stress was obtained \\  & POIs of (normal = \(-1.8\) mmHg; keratoconus = \(7.1\) mmHg; keratoconus = \(13.9\) mmHg) & & & \\  & & & & \\  & & & & \\  & & & & \\ \hline \hline \end{tabular}
\end{table} 
Table 4: _Cont._  
Figure 9: Comparison of maximum principal stress parameters identifying the mean/average of the different models described in this paper. This is classified as grade IV keratoconus according to the Amsler Krumeich scale, and it produces high corneal eccentricity in areas of ectasia [40]. The current methods for keratoconus diagnosis are keratometry and photo and video keratoscopy, and they have proven efficient [41; 42]. This paper presents two models of keratoconus-type ectasia with different degrees or severity and a healthy model. In the first healthy model, we observed a curvature that varied between 593 mm and 596 mm in the apical area. However, in the second and third models, which already presented corneal ectasia, we had to consider the different levels of severity based on the corneal radius (mm). All corneal radius curvatures are 4 mm [43]. In our study, we observed statistically significant differences in the amplitude of the anterior chamber between the three groups--normal patients with keratoconus and keratoglobus--as well as in the dimensions, with an increase in the same order in an anteroposterior direction (Figure 10). Recent studies have also compared changes in this variable between similar study groups. In some cases, no significant difference was found, while in others, the behavior of the curve was observed. Finally, these models have significant differences regarding deformation and maximum principal stress.