## 3 Results
### The Average ppRPE/BM Cross-Sectional Angle (\(\Gamma\)) across all Radial Directions  
Figure 7 depicts the representative distribution of \(\Gamma\) across the 12 radial directions before and after LP in the right eye and left eye, respectively. It is clear that the averaged ppRPE/BM layer angle \(\Gamma\) varied considerably across the radial directions. Specifically, the distribution pattern of the \(\Gamma\) showed a sine-like curve for the right eye, while a cosine-like curve for the left eye. The distribution pattern of \(\Gamma\) before and after LP were almost identical, indicating that LP-induced \(\Delta\Gamma\) is independent of the radial scan directions. Moreover, such distribution patterns were observed in 29 out of 30 eyes.  
For the 16 right eyes, the standard deviations of \(\Gamma\) ranged from 0.20\({}^{\circ}\) to 1.19\({}^{\circ}\) before LP, and they ranged from 0.19\({}^{\circ}\) to 1.18\({}^{\circ}\) after LP (Figure 8). For the 14 left eyes, the standard deviations of \(\Gamma\) ranged from 0.26\({}^{\circ}\) to 1.34\({}^{\circ}\) before LP, and they ranged from 0.28\({}^{\circ}\) to 1.31\({}^{\circ}\) after LP. The standard deviations of \(\Delta\Gamma\) ranged from 0.07\({}^{\circ}\) to 0.20\({}^{\circ}\) in the 16 right eyes, and they ranged from 0.05\({}^{\circ}\) to 0.29\({}^{\circ}\) in the 14 left eyes. The standard deviations of \(\Delta\Gamma\) were significantly smaller than those of \(\Gamma\) before or after LP. The standard deviations of \(\Gamma\) before LP were found not significantly different from those after LP in all eyes. Furthermore, the repeated measures ANOVA analysis revealed that the ppRPE/BM layer angle change (\(\Delta\Gamma\)) did not vary significantly across the radial directions (\(p\)-value \(>\) 0.01) in both right eyes  
Figure 7: The representative distribution of \(\Gamma\) across the 12 radial scans before and after LP in both eyes of one patient.  
and left eyes. In addition, no significant difference was found between right eyes and left eyes with respect to the standard deviations of \(\Gamma\) before LP, \(\Gamma\) after LP, or \(\Delta\Gamma\).  
The mean \(\Delta\Gamma\) across the 12 radial directions in the 16 right eyes and 14 left eyes are further depicted in Figure 9. Among them, 7 right eyes and 6 left eyes were found to have a positive \(\Delta\Gamma\) after LP. It was also observed that the \(\Delta\Gamma\) after LP could be dramatically different or even opposite between the right eye and left eye of the same individual. In addition, the paired tests revealed that 15 right eyes (94%) and 14 left eyes (100%) had significant ppRPE/BM layer angle changes following LP (\(p<0.01\)). Only the right eye of patient 15 did not show significant changes of \(\Gamma\) following the LP.  
Figure 8: The standard deviations of \(\Gamma\) before LP, \(\Gamma\) after LP, and \(\Delta\Gamma\). The solid dark line indicates the median, and the circle indicates the outlier. (* indicates the standard deviations of \(\Delta\Gamma\) were significantly different from that in \(\Gamma\) before and after LP).  
Figure 9: The mean \(\Delta\Gamma\) across the 12 radial directions in the 16 right eyes and 14 left eyes. Error bar: \(\pm\) standard deviation.