## 5 Discussion  
Macular degeneration is a chronic disease that affects central vision; as the macular region deteriorates, it loses the ability to produce clear images of the focused objects. The visual system needs to re-adapt its behaviour to overcome this condition by shifting the gaze away from the object of interest and reallocating it in the periphery (outside the area of visual loss). Quickly developing a new adaptive mechanism is essential for patients  
Figure 10: Polar histograms of gaze direction in respect to target for group 1 (**G1**) and group 2 (**G2**) across the blocks (1, 2, and 3). Above each polar histogram, the mean resultant length (r) and the average angle (avgAng) with the corresponding SD of gaze-target direction are represented. The long red line represents the average angle, the black bold semicircle at the end of the red line indicates the SD. The red arrow overlapped on top of the long red line is the mean resultant vector. suffering from macular degeneration to detect objects of interest, such as incoming cars or bicycles. Most patients with central visual loss take up to three (3) months to adapt, and only one out of three manages to direct their eyes correctly towards the object of interest [9, 48]. Other authors have already used VR for rehabilitation and training of this eccentric fixation behaviour using patients [13, 14, 15]. However, one of the major challenges for these studies is that patients have different types of scotomas with different shapes and positions, and for this reason, patients require individualized augmentations. The mixed results obtained so far regarding individual augmentation on patients complicate its translation to clinical practice. The current study investigates gaze behaviour during salience augmentation for standardised central scotoma simulation during tracking of a moving object. Previous studies only looked at changes in normally sighted participants with simulated scotomas without further testing how augmentations might change their behaviours. In our case, a modified version of a VR Pong game was presented to participants where they had to pursue a ball, stopping it from exiting the play area by moving the paddles, and they also had to acknowledge changes in the ball's colour. The group whose participants initially experienced an advanced scotoma simulation, and only afterwards salience around the scotoma was presented, a significant change in gaze behaviour was observed. In comparison to the normal condition, during the salience augmented scotoma condition, the target was placed above the scotoma edge both when considering 5\({}^{\circ}\) as well as 6\({}^{\circ}\) radius (Figure 9, G1). Furthermore, the polar histograms show that, even if the mean resultant vector did not increase across blocks, gaze position started to be directed more and more towards the lower hemifield in the augmented condition. On the other hand, no such trend could be observed across blocks for the scotoma simulation condition (Figure 10, G1). The tendency observed for the salient augmented condition is in accordance with previous findings [4] where 57% of macula degeneration patients had better attention preference for the lower hemifield and where most patients with central visual loss direct their gaze [21, 48, 49, 50, 51]. For the second group, a change in gaze behaviour for both simulated conditions was also achieved. A significant change was observed during the scotoma simulation, with the target being placed further away from the scotoma edge when taking into account 5\({}^{\circ}\) and also 6\({}^{\circ}\) extension in the coverage range (Figure 9, G2), when compared with the baseline condition (normal). The polar histogram revealed a similar trend for the augmented condition to the one observed by the first group. The gaze's direction started having a specific directionality that was kept throughout the other two blocks.