Afferent pupil defect testing in a VR headset
Virtual reality, VR, headset-based electronic systems that can be used to perform afferent pupil defect, APD, tests. The systems may improve the sensitivity, consistency, and ease of application of the APD tests. Other aspects are also described.
1 . A headset-based system, the system comprising:
a headset comprising:
a left visible light display;
a left compartment adapted to fit over a left eye of a user and block out environment light;
a right visible light display;
a right compartment adapted to fit over a right eye of the user and block out the environment light, wherein the left and right compartments are configured so that when the headset has been fitted over the user's eyes i) the user cannot see the right display using only their left eye and ii) the user cannot see the left display using only their right eye;
light sensors disposed inside the left and right compartments to detect levels of the environment light that leaks into the left compartment or the right compartment; and
a non-visible light-based eye tracking subsystem that produces tracking data for the left eye and for the right eye; and
a processor configured to, when the headset has been fitted over the user's eyes;
i) signal the left display and the right light display to simultaneously display a background with a first level of brightness, and then
ii) signal only one of the left display or the right display to display a stimulus of a predetermined brightness that is brighter than the first level of brightness, and then
iii) signal only the other one of the left display or the right display to display the stimulus, and
iv) during i)-iii) record sizes of a left pupil and a right pupil over time based on the tracking data from the eye tracking subsystem and store the recorded sizes as a data set associated with the user,
wherein the processor is further configured to record the levels of the environment light for the left compartment and the right compartment representing an external light contribution while the headset is fitted over the right and left eyes of the user.
2 . The system of claim 1 wherein the processor is further configured to add a middle background interval, by signaling the left display and the right display to simultaneously display the background after ii) and before iii).
3 . The system of claim 2 wherein the processor is further configured to interpret the recorded sizes to determine speeds at which the left pupil and the right pupil constrict and then recover in the middle background interval and store the determined speeds as further data associated with the user.
4 . The system of claim 1 wherein the processor is further configured to:
mark the data set where the recorded sizes of the left pupil and the right pupil, over a same time interval of at least one second where the background is being displayed, differ by more than a threshold.
5 . The system of claim 1 wherein the processor is further configured to:
mark the data set where the left pupil and the right pupil do not constrict symmetrically, over a same time interval of at least one half of a second, in response to the stimulus being displayed.
6 . The system of claim 1 wherein the processor is further configured to:
signal the left display and the right display to simultaneously display the stimulus for a given time interval;
record sizes of the left pupil and the right pupil, based on the tracking data from the eye tracking subsystem over the given time interval, and store the recorded size as another data set associated with the user; and
mark the another data set where the recorded sizes of the left pupil and the right pupil differ by more than a threshold.
7 . The system of claim 1 wherein the processor is further configured to signal the left display or the right display to illuminate the left eye or the right eye at a mesopic level while displaying a target stimulus.
8 . The system of claim 3 wherein the processor is configured to display the recorded sizes of the left pupil and the right pupil over time, or the determined speeds at which the left pupil and the right pupil constrict and recover, as part of a history of afferent pupil defect testing performed on the user.
9 . The system of claim 1 wherein the background is dark or no light.
10 . The system of claim 1 wherein the stimulus is a light region.
11 . The system of claim 1 wherein the stimulus is displayed between one-half second and two seconds.
12 . The system of claim 1 wherein the recorded sizes of the left pupil and the right pupil over time have a resolution of less than one millimeter.
13 . The system of claim 1 wherein the processor is external to the headset, and the headset comprises a wired or wireless communications network interface through which the tracking data from the eye tracking subsystem is sent to the processor.
14 . The system of claim 1 wherein the eye tracking subsystem is an infrared pupil tracking subsystem that produces images of pupils of the left eye and the right eye.
15 . A method for pupil defect testing comprising:
i) signaling a left display and a right light display of a headset to simultaneously display a dark background, and then
ii) signaling only one of the left display or the right display to display a light stimulus, and then
iii) signaling only the other one of the left display or the right display to display the light stimulus,
v) during i)-iii) record sizes of a left pupil and a right pupil of a user of the headset over time, based on tracking data from an eye tracking subsystem in the headset, and store the recorded sizes as a data set associated with the user, and
vi) marking the data set where the recorded sizes of the left pupil and the right pupil, over a same time interval of at least one second where the background is being displayed, differ by more than a threshold.
16 . The method of claim 15 further comprising adding a middle background interval by signaling the left display and the right display to simultaneously display the dark background after ii) and before iii).
17 . The method of claim 15 further comprising marking the data set where the left pupil and the right pupil do not constrict symmetrically, over a same time interval of at least one half of a second, in response to the stimulus being displayed.
18 . The method of claim 15 further comprising:
signaling the left display and the right display to simultaneously display the stimulus for a given time interval;
recording sizes of the left pupil and the right pupil, based on the tracking data from the eye tracking subsystem over the given time interval, and store the recorded size as another data set associated with the user; and
mark the another data set where the recorded sizes of the left pupil and the right pupil differ by more than a threshold.