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. 2023 Jun 1;12(6):22.
doi: 10.1167/tvst.12.6.22.

Detection of Relative Afferent Pupillary Defects Using Eye Tracking and a VR Headset

Dominik Bruegger  1   2 , Hilary M Grabe  1 , Rino Vicini  1 , Muriel Dysli  1 , David Lussi  1 , Mathias Abegg  1
Affiliations

Detection of Relative Afferent Pupillary Defects Using Eye Tracking and a VR Headset

Dominik Bruegger et al. Transl Vis Sci Technol. .

Abstract

Purpose: The purpose of this study was to assess the feasibility of detecting relative afferent pupillary defects (RAPDs) using a commercial virtual reality headset equipped with an eye tracker.

Methods: This is a cross-sectional study in which we compare the new computerized RAPD test with the traditional clinical standard using the swinging flashlight test. Eighty-two participants including 20 healthy volunteers aged 10 to 88 years were enrolled in this study. We present a bright/dark stimulus alternating between the eyes every 3 seconds using a virtual reality headset, and we simultaneously record changes in pupil size. To determine the presence of an RAPD, we developed an algorithm analyzing the pupil size differences. For the assessment of the performance of the automated and the manual measurement a post hoc impression based on all available data is created. The accuracy of the manual clinical evaluation and the computerized method is compared using confusion matrices and the gold standard of the post hoc impression. The latter is based on all available clinical information.

Results: We found that the computerized method detected RAPD with a sensitivity of 90.2% and an accuracy of 84.4%, as compared to the post hoc impression. This was not significantly different from the clinical evaluation with a sensitivity of 89.1% and an accuracy of 88.3%.

Conclusions: The presented method offers an accurate, easy to use, and fast method to measure an RAPD. In contrast to today's clinical practice, the measures are quantitative and objective.

Translational relevance: Computerized testing of Relative Afferent Pupillary Defects (RAPD) using a VR-headset and eye-tracking reaches non-inferior performance compared with senior neuro-ophthalmologists.

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Conflict of interest statement

Disclosure: D. Bruegger, (O); H.M. Grabe, None; R. Vicini, None; M. Dysli, None; D. Lussi, None; M. Abegg, (O)

Figures

Figure 1.
Figure 1.
Photograph of a participant wearing the VR headset, and the output on the screen during the examination, showing the Image feed from the IR-eye tracking cameras used for alignment and compliance monitoring. Beside the camera feed the graphical user interface of the custom developed software for data visualization and recording is shown.
Figure 2.
Figure 2.
Top two plots: Time-synchronized pupil size recordings of multiple light switches between the left and right eyes from one patient with a right sided RAPD. The top panel shows recordings from the right eye; the middle panel corresponds to the left eye. Grey = single recordings; black = averaged traces with outliers removed; horizontal bars = amplitude values for further processing. Bottom panel = Illumination sequence for the right and left eyes, with illuminated = white, and dark = grey.
Figure 3.
Figure 3.
Top: Scatter plot shows the pre-stimulus amplitude difference (i.e. the difference of maximal dilation with left sided illumination and right sided illumination on the y-axis). The x-axis shows the difference of pupillary amplitude with right sided illumination and left sided illumination. Positive RAPD values correspond to a left sided RAPD, whereas negative values indicate a right sided RAPD. The tilted line separates the left and right sided RAPD. Bottom-left: Correlation between mean defect of the visual field and RAPDSize (for definition see Methods). Bottom-center: Correlation between RAPDSize and the right- and left difference in logMAR visual acuity. Bottom-right: Correlation between RAPDSize and the required neutral density (ND) filter to neutralize the RAPD in the swinging flashlight test. Positive RAPD values correspond to a left sided RAPD, while negative values indicate a right sided RAPD.
See this image and copyright information in PMC

References

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