## 2 Materials and Methods
### Laser Beam Propagation into the AC  
Previously to the irradiation experiments, we analyzed (WinLens3D Basic) the propagation of the pump-probe beams to optimize the experimental setup of the STM technique through a pig eye model,and to know the size of the pump beam waist radius within the AC. Figure 5 illustrates the simulation of the probe beam propagation through a pig eye model into the AC. The simulation parameters of the probe beam and the frontal width of a mitotic iris (see Figure 5) were obtained experimentally, while the eye model parameters were obtained from a database [24; 25]. The simulation shows the effect on the probe beam when varying the incidence angle \(\theta\) of the probe beam, which is displaced by a \(\delta\) (1.1 mm) distance with respect to the incidence spot of the pump beam on the cornea surface, and considering that the cavitation bubbles are generated just below the cornea.  
In Figure 5, it is shown how the probe beam fills the cavitation zone and, at the same time, it hits a region on the iris off of which it is reflected. For example, at an incident angle of \(52^{\circ}\) (see Figure 5a), both conditions are met, but if the incident angle changes to \(49^{\circ}\), as shown in Figure 5b, we have losses of the probe beam, since it partially misses the iris, regardless of if the cavitation zone is fulfilled. If the angle increases to \(60^{\circ}\), the probe beam does not miss the iris, but the reflected beam coming out is too close to the sclerocorneal limbus, where the probe beam is fully screened (see Figure 5c).  
Figure 6 shows the propagation of the pump beam focused with a 12 mm focal-length lens (NA = 0.36) into the AC of the pig eye model. The software WinLens3D Basic uses the solution to the paraxial wave equation to define the beam waist radius \(W_{0}\) (\(1/e^{2}\)) as a function of the wavelength \(\lambda\), beam quality factor \(M^{2}\), Rayleigh range \(Z_{R}\), beam diameter D, and beam divergence \(\theta\). With the  
\begin{table}
\begin{tabular}{c c c c} \hline \hline
**Eye Label** & **Zone I (\(\sigma\), \(\upmu\)s)** & **Zone II (\(\sigma\), \(\upmu\)s)** & **Zone III (\(\sigma\), \(\upmu\)s)** \\ \hline Diamond & 4.10 & 4.46 & 4.32 \\ Circle & 3.28 & 3.71 & 3.80 \\ Rectangle & 4.83 & 2.25 & 1.52 \\ Zone & \(\sigma\) [\(\upmu\)s] & IQR [\(\upmu\)s] & \\ I & 6.22 & 9.4 & \\ II & 6.51 & 11.89 & \\ III & 4.99 & 7.7 & \\ \hline \hline \end{tabular}
\end{table}
Table 1: Standard deviation \(\sigma\) and interquartile range (IQR) from the data shown in Figure 4.  
Figure 5: Simulation on WinLens3D Basic of the probe beam propagation through the AC. (**a**), (**b**), and (**c**) are the results for incident angles of \(52^{\circ}\), \(49^{\circ}\), and \(60^{\circ}\), respectively. The star indicates the cavitation bubble zone.  
ETP previously obtained experimental data for the free propagation pump beam (\(\lambda\), \(\theta\), \(M^{2}\) and \(Z_{R}\)) using the ETP, we computed the value of \(W_{0}\) for both the pig eye model and free space, obtaining \(W_{0}\) = 8.4 \(\upmu\)m and 4.6 \(\upmu\)m, respectively, which agrees well with the experimental measurements and theoretical values previously obtained.