Figure legends
Figure 1. Panel A. The Skew VOG-Test is a portable device consisting of a tablet screen that is mounted on the back of a bucket. The subject is equipped with VOG googles for measuring eye position using pupil-tracking software. Panel B. APCT: A trained orthoptist estimated the induced skew performing the alternate cover test with prisms opposed to the subjects left eye. The prisms were changed in diopter size until there was no corrective vertical eye movement during the alternate prism cover test.
Figure 2. Vertical positions of the right eye over time are shown with black lines. Periods of right and left eye occlusions are plotted in front of white and grey backgrounds, respectively. Curves A to F show increasing foil strengths respectively (A 1 PD foil (0.57°), B) 2 PD foil (1.14°) C) 4 PD foil (2.28°) D) 6 PD foil (3.42°) E) 8 PD foil (4.56°) and F) 10 PD foil (5.70°)). Please note, that hypermetric saccades have not been included by the VOG algorithm.
Figure 3. Correlation between the alternate cover test with prisms (performed by an orthoptist) and VOG device (Pearson’s R2= 0.606, p<0.05).
Figure 4. Bland-Altman plot: analysis of the agreement between the APCT and the VOG. The difference between APCT and the VOG plotted against the mean value for both the ACT and the VOG. The solid line shows the mean of the differences, while the dashed lines represent the superior and inferior limits of agreement.
Figure 5. Median prism diopters (PD) obtained by VOG-measurement (white boxes) and by the orthoptist using APCT (grey boxes). On the x-axis, the different FPs are given in prism diopter.