## 5 Discussion
This direction was kept when scotoma simulated participants had to play the game without augmentation, and the value increased even more across the blocks. Additionally, by the end of the third block of the central scotoma condition, the bias strength tripled the value that subjects had when they finished the last block of the augmented condition (Figure 10, G2). The trend that emerged was to position the gaze above the target. However, even if in an uncommon position, the gaze position above the target was still in line with previous studies [25]. Based on the results, we hypothesise that presenting salient cues at the early stages of central visual loss can help build a preferred gaze location. In contrast, prior experiences of wild gazing in the presence of a scotoma may delay this choice. These results also point towards developing a preferred retinal locus (PRL) position for moving targets. Subjects presented with advanced stages of a central scotoma who have not undergone any training and had not been presented with visual cueing usually develop an unclear and variable preferred gaze positioning. This variability is reduced when augmentation is implemented and the previously adopted positioning changes. However, this behavioural change might take longer due to this previously positioning that the subject already has. Some potential limitations should be acknowledged, considering the pilot nature of the study. For instance, future studies will need to replicate our findings with greater samples. Moreover, the present study indicates that different adjustments on the augmentation might be needed depending on the stage of the macular degeneration. In this study, the HTC Vive Pro Eye, which is known to have an end-to-end latency between 58.1 ms [31] and 80 ms [32] was used. Thanks to the colour recognition subtask and the scotoma radii thresholding, the data were corrected for eye-tracking delays (25 ms). However, this end-to-end latency [31; 32; 44] is not stable as it can be seen in the results, and therefore may have influenced the scotoma positioning similarly to previous gaze-contingent paradigms [44; 45]. After data pre-processing, a 1\({}^{\circ}\) error in scotoma coverage for the majority of subjects tested was found. This finding allowed a better understanding of the occluded area and allowed us to correct for it when analysing the results. However, it also decreased the area that was intended to be covered. An additional limitation of the current system are errors in the IPD estimation. This type of error can lead to a breakdown of binocular fusion, with errors in correctly focusing on a target [52]. However, as calibrations were performed before each condition and manual adjustments of the scotoma were performed on a trial basis, this error can be neglected. Despite the limitations discussed above, a standardised scotoma simulation of 5\({}^{\circ}\) was still achieved for eight subjects. The simulation changed the gaze behaviour compared to normal conditions. In general, our results confirm what was previously published [16; 17; 18; 19; 20; 24], i.e., standardised scotoma simulations and augmentations help study and train gaze behaviours. Virtual reality gaming proved to be a more entertaining task, resulting in greater participants' engagement and rapid adaptation. The similar results obtained in a VR 2D world to previous literature is the first step for building a model for a future, more complex and immersive reference system. Once a model of PRL development with the key characteristics and behaviours has been established more immersive and realistic virtual scenarios can be used, such as, for example, crossing the street scenarios that involve tracking a moving target in the periphery.