Eye-tracking color vision test

Abstract

The goal is to improve the sensitivity, consistency, and ease of application of the test. A virtual reality (VR) headset-based and open display-based electronic system that can be used to administer color vision tests can improve the test's sensitivity, consistency, and ease of application. Other aspects 112846.P1160WO are also described.

Description

[Technical Field]

[0001] (CROSS-REFERENCE TO RELATED APPLICATIONS) This non-provisional patent application claims the benefit of the earlier filing date of U.S. Provisional Patent Application No. 63 / 431,223, filed December 8, 2022.

[0002] FIELD OF THE INVENTION One aspect of the present disclosure relates to a portable head-worn device that can be used to perform hands-free color vision testing of a wearer's eyes. Other aspects include eye-tracking color vision testing using motion stimuli. [Background technology]

[0003] Traditionally, color vision is assessed using a pseudo-isochromatic plate (PIP), which hides patterns in an image consisting of many monochromatic bubbles that vary from bubble to bubble within a range of size, hue, and intensity. A patterned symbol created from a group of adjacent bubbles with a different hue range than the background bubble is visible to individuals with normal color vision, but is hidden by individuals with impaired color vision or sensitivity.

[0004] Traditional PIP tests present static images on a printed sheet and individuals are asked to identify the image they are viewing, usually by a verbal response. Electronic versions of these tests exist, which are similar in test strategy in that individuals are asked to look at or enter numbers or letters to select from a set of options. Summary of the Invention

[0005] One aspect of this disclosure is a stereoscopic system that can be used to perform color vision tests or exams in a repeatable manner that not only quantifies the degree of color blindness in the individual being tested, but can also show its progression over time. When virtual reality (VR) headsets are used, these systems can improve the consistency and ease of administering color vision tests in a variety of ambient lighting environments in a more efficient (less time-consuming) manner. The results of the test can then be used, for example, by an eye care professional to diagnose a person's health problem that may require further testing or recommended treatment. Another aspect is directed to eye-tracking color vision tests that use motion stimuli.

[0006] The above summary does not include an exhaustive list of all aspects of the present disclosure. The present disclosure is intended to include all systems and methods that may be implemented from any suitable combination of the various aspects summarized above, as well as those disclosed in the Detailed Description below and particularly pointed out in the Claims section. Such combinations may have advantages not described in the above summary. [Brief explanation of the drawings]

[0007] Some aspects of the disclosure herein are illustrated by way of example, and not by way of limitation, in the figures of the accompanying drawings. Like references indicate like elements in the figures. It should be noted that references to "an" or "one" aspect in the present disclosure do not necessarily refer to the same aspect, but rather mean at least one. Also, for the sake of brevity and to reduce the total number of figures, a given figure may be used to illustrate features of more than one aspect of the disclosure, and not all elements of a figure may be required for a given aspect. [Figure 1] FIG. 1 is a diagram of an exemplary virtual reality (VR) headset-based system for color vision testing. [Figure 2A] FIG. 1 is a flow diagram of an exemplary method for color vision testing. [Figure 2B]1 shows an exemplary PIP with a hidden shape in a colored bubble background and several user selectable shapes displayed to the user's eye. [Figure 3] FIG. 10 is a flow diagram of another exemplary method for color vision testing. [Figure 4] FIG. 1 is a flow diagram of an exemplary method for array-based color vision testing. [Figure 5] FIG. 1 is a flow diagram of an exemplary method for color vision testing using motion stimuli. [Figure 6] FIG. 10 is a flow diagram of yet another method for color vision testing using motion stimuli. DETAILED DESCRIPTION OF THE INVENTION

[0008] Some aspects of the present disclosure will now be described with reference to the accompanying drawings. Wherever the shape, relative position, and other aspects of the described parts are not explicitly defined, the scope of the present invention is not limited to only the parts shown for illustrative purposes only. Also, while many details are set forth, it will be understood that some aspects of the disclosure can be practiced without these details. In other instances, well-known circuits, structures, and techniques have not been shown in detail in order not to obscure an understanding of this description.

[0009] FIG. 1 is a diagram of an exemplary virtual reality (VR) headset-based system that can be used for color vision testing. The system is an example of a stereoscopic system, and some of the aspects described below are also applicable to other stereoscopic systems, such as those using lenticular arrays. The system of FIG. 1 consists of a VR headset 1 worn over the eyes of a user (observer) as shown. It has a wired or wireless communication network interface for communicating data with an external computing device 9, such as a tablet computer, laptop computer, or the like. A human operator, such as an eye care professional (ECP), can simply interact with software running on one or more microelectronic data processors (commonly referred to as "processors") in the system to conduct a color vision test. Once the software is launched or initialized, it can automatically (without operator input) conduct the test by controlling various electronic and optical components of the VR headset 1. The software may have components executed by a processor within the VR headset 1 and components executed by a processor that is part of the external computing device 9. Some of these software components may run on either the VR headset 1 or the external computing device 9. The software may interact with the operator through a graphic user interface component that uses the touch screen of the external computing device 9 to present the results of the color vision test.

[0010] The VR headset 1 may have a goggle-like form factor, as shown, that blocks all ambient lighting outside the VR headset 1 and creates a dimmed environment around the user's eyes (independent of ambient lighting outside the VR headset 1). The VR headset 1 may consist of a left visible light display 3 coupled to a left compartment 5 that fits over the user's left eye and a right visible light display 4 coupled to a right compartment 6 that fits over the user's right eye. The left and right compartments are configured, e.g., molded and opaque, such that (when the VR headset 1 is fitted over the user's eyes) the user cannot view the right display 4 using only their left eye and the user cannot view the left display 3 using only their right eye. Also, the left and right displays need not be separate display screens but instead can be left and right halves of a single display screen. The displays may be implemented using technology that provides sufficient display resolution or pixel density, such as liquid crystal display technology, organic light-emitting diode technology, etc. Although not shown, there may be eyecups on each of the left and right displays that contain optical elements (e.g., lenses) that function to give the user the illusion that the objects the user views in the displays (in this example, pine trees, which may be displayed in 2D or 3D) are at a greater distance than the actual distance from the user's eyes to the displays, thereby allowing for more comfortable viewing. VR headset 1 may also incorporate trial lenses or some other adjustable refractive optics to accommodate patients with different refractive errors.

[0011] The VR headset 1 also has a non-visible light based eye tracking subsystem 8, for example an infrared pupil tracking subsystem, the output eye tracking data of which can be interpreted by a processor to independently track the left and right eye positions and detect blinks and the pupil size or diameter of each eye in a manner invisible to the user.

[0012] The system includes a processor, e.g., one or more microelectronic processors that are part of the external computing device 9, one or more microelectronic processors within the housing of the VR headset 1, or a combination of processors within devices that communicate with each other through a communications network interface. The processor is configured to perform a color vision test when the headset is worn by a user's eyes via software or instructions stored in a machine-readable medium such as a solid-state memory. To do so, the processor signals a left visible light display or a right visible light display to display stimuli for the color vision test that the user views using their left or right eye, respectively. The processor may be configured to signal a further display, e.g., a display screen of the external computing device 9, to display the progress or results of the test. The test may proceed as follows, with reference to FIG. 2A .

[0013] The user is instructed, for example, by an eye care professional (ECP), either in person or via prerecorded instructions played over a speaker, to place the VR headset 1 over their eyes and locate the stimuli displayed by the left or right visible light display. As shown in the flow diagram of FIG. 2A, the processor can then begin the test in operation 13 by signaling the left or right visible light display to simultaneously display i) a single pseudoisochromatic plate (PIP) for color vision testing, e.g., an Ishihara table, and ii) several user-selectable shapes. See FIG. 2B, which shows an example of nine user-selectable shapes, respectively, as the numbers 1 through 9. The user-selectable shape may be a number, letter, or another symbol hidden within the PIP; in FIG. 2B, the shape is the number "8." While the PIP is shown, the processor uses tracking data from the eye tracking subsystem 8 to record the tracked position of the right or left eye as the right or left eye moves and the user views the PIP stimuli (operation 15). The processor interprets the tracked position of the right or left eye to determine a user-selected figure selected by the user from among several user-selectable figures (multiple-choice question) (operation 16). The processor then records an indication of whether the user viewed the stimulus figure in the PIP as a correct or incorrect answer to the question based on a comparison of the stimulus figure and the user-selected figure (operation 18). The processor then repeats operations 13-18 one or more times, each time with a different stimulus figure. This results in several indications being recorded as to whether the user viewed (correctly or incorrectly) various stimulus figures. Thus, the processor may complete the test for the user without receiving manual or verbal input from the user regarding whether the user viewed the stimulus figure.

[0014] In one embodiment, the processor in act 16 is configured to interpret tracking data from the eye-tracking subsystem to detect blinks by the user while the PIP table is displayed in act 13. The processor then determines the user-selected shape based on detected blinks that occur while the user gazes at the particular user-selected shape. In another embodiment, the processor determines the user-selected shape based simply on detecting that the user's gaze remains fixed on the particular user-selected shape for a period of time.

[0015] In another aspect, the processor quantifies hesitation by the user in terms of the time interval between the appearance of the PIPs and the user selecting one of the shapes. The hesitation can be used by the processor to provide more information than a simple binary correct / incorrect selection of a shape. For example, if a user quickly correctly selects some PIPs compared to other PIPs, it can provide additional information about the color sensitivity of the user's eyes.

[0016] In one aspect, the processor executes operations 13-18 multiple times, each time alternating display of the PIP between the left visible light display and the right visible light display in operation 13, and in operation 18, the indication as to whether the user saw the stimulus graphic in the PIP refers to only the left eye or only the right eye, respectively.

[0017] In the example of FIG. 2B, the nine user-selectable shapes are not only visible (each number is visible to the user) but are also arranged linearly below the table. As another example of hands-free color vision testing, a system could display the user-selectable shapes in a clock face arrangement, with a single table having a single hidden number selected from 1 to 12 displayed therein, for example, in the center of the clock face (with or without moving hands). In such a clock face / clock face version, the user-selectable shapes could be replaced with generic marks that do not include any numbers within the clock face (e.g., only at the 12, 3, 6, and 9 positions on the clock face). In either case, the user attempts to recognize the hidden number displayed in the table and is then instructed to look toward or in the direction of the clock face where the hidden number would be expected to be located on the clock. For example, if the user recognizes the hidden number as 6, the user would look vertically down; if the user recognizes the hidden number as 3, the user would look horizontally to the right, and so on. Numbers can be added to all 12 positions on the clock face.

[0018] In yet another embodiment, and referring now to the flow diagram of FIG. 3 , beginning at operation 21, a color vision test is conducted by a processor signaling a display to display a PIP containing a hidden stimulus graphic, e.g., a letter “Y” that includes an elongated mark branching off at a bifurcation point. As described above, the processor uses tracking data from the eye tracking subsystem 8 to record (at operation 23) the tracked movement of the right or left eye as the right or left eye moves while the PIP is shown. The processor then interprets (at operation 25) the tracked movement of the right or left eye as being upward along the elongated mark. For example, the user may be tracing the vertical line of the letter “Y.” The processor then records an indication of whether the user viewed the stimulus graphic in operation 26 based on interpreting the tracked movement as indicating hesitation by the user when reaching the bifurcation point or branch of the letter “Y.” The processor may quantify hesitation here in terms of the time interval between arriving at the bifurcation point and resuming tracing along one of the branches. The processor can use this to provide more information than just whether the user saw the branch correctly or incorrectly.

[0019] Referring now to Figure 4, this is a flow diagram of an exemplary method for array-based color vision testing. This test is performed by a processor within the VR-based headset system of Figure 1. When a user places the VR headset 1 on their eyes and can be instructed to search for a visual stimulus, the processor is configured to signal the left or right visible light display to simultaneously display a sequence of several tables, each adjacent to one another, e.g., all shaped like a disk or a square, in operation 41. Note that the sequence need not form a straight line, as it may be a curve, nor need it be an open sequence, as it may instead form a closed loop.

[0020] The user is now instructed to rearrange the tables into the sequence in the correct color order. For example, the user is instructed to identify the table they feel is closest in color to the starting table. The starting table may be highlighted or may be at one end of the sequence and remain fixed during inspection. Once the user identifies a first selected table, the first selected table is "picked up" and then "placed" adjacent to the starting table. The user then chooses a second table that is closest in color to the first table, and the second table is then picked up and moved adjacent to the first table, where it is placed. This process is repeated until the user or processor determines that the rearrangement of the sequence is complete, e.g., all remaining tables except the first table have been picked up at least once. This process can have variations, such as allowing the user to make all decisions about which table to select next, or allowing the user to go back and rearrange previously arranged tables.

[0021] To enable a hands-free version of the table arrangement process, the processor is configured in operation 43 to record tracked movements of the eye (left or right eye) using tracking data from the eye tracking subsystem 8 as the eye moves while the sequence is displayed in operation 41. The processor then interprets the tracked movements of the eye (operation 45) as a) picking up a selected table, then b) dragging the selected table to a different position in the sequence, and then c) placing the selected table in a different position. For example, the tracked movements of the eye may be interpreted as the user gazing at the table (rather than glancing at it), which is then interpreted as picking up or selecting the table or placing the table (depending on the context around the tracked movements of the eye). Alternatively or in addition to interpreting the tracked movements of the eye, the processor detects a first blink of the eye when the gaze is on a table as picking up the table and then a second blink of the eye as placing the selected table in operation 45. The location of the table is indicated by the location of the user's eye gaze at the moment of the detected blink. Operation 45 may be repeated multiple times to result in a rearranged sequence of tables when a determination is made by the processor that the test is complete (operation 47). The processor then evaluates the rearranged sequence in operation 48 to determine the user's color vision score, for example, according to any one of several available techniques, such as Farnsworth D-15.

[0022] Referring to FIG. 5, this is a flow diagram of a method for color vision testing in which a motion stimulus is displayed to a user. This method can be implemented by a processor of a computer system having a visible light display and a non-visible light-based eye-tracking subsystem. The display can be a tabletop display screen, and the eye-tracking subsystem can be mounted on the tabletop display screen so that the user's eyes can be monitored while the user views the display screen. Alternatively, the display and eye-tracking subsystem can be attached to or integrated into a VR headset that the user wears over their eyes, such as the VR headset 1 described above in connection with FIG. 1. The method begins at operation 51, in which the processor can signal the visible light display to display a motion stimulus within the left eye's field of view, the right eye's field of view, or both the left and right eyes' fields of view simultaneously. The motion stimulus includes a background and a region, e.g., a PIP, that contrasts in color with the background. The "color pair" in any PIP is the hue of the object or shape and the hue of the background, intended to test a specific type of color blindness. The region changes position or moves relative to the rest of the motion stimulus to form a pattern. The regions may hereinafter be referred to as figures or objects hidden within the PIP and moving within the PIP. The expectation here is that different objects or figures (with different movement paths) will be apparent to people with different types or degrees of color blindness. For example, when presenting two objects, in most cases, the user is expected to observe only one of the two objects, which is the object that appears with greater contrast to the user.

[0023] In operation 52, the processor uses tracking data from the eye tracking subsystem 8 to record the tracked movement of the right eye or the tracked movement of the left eye as the right eye or the left eye moves while the motion stimulus is displayed in operation 51. The processor also interprets the tracked movement to determine whether the user's gaze is following a pattern (operation 54). These operations 51-54 are repeated multiple times, each time with a different motion stimulus, and then in operation 56, the processor evaluates the interpreted tracked movement to determine the user's color vision score, e.g., how sensitive the user is to the color contrast in each motion stimulus based on how accurately the user's eyes tracked the pattern in the motion stimulus.

[0024] In one embodiment, there may be a single region within the user's overall visual field that slowly changes location over time. In another embodiment, there may be multiple such regions simultaneously appearing in various locations within the user's visual field, e.g., each region being a shape effectively hidden within its respective PIP (hidden only from individuals with color vision deficiencies). There may be multiple such PIPs that are uncorrelated and displayed simultaneously. In such a scenario, the user may be instructed to find the hidden shape (within its respective PIP or table) that appears with the highest contrast from its background. If there are multiple such tables with similar levels of color contrast, and the user's gaze is interpreted as gazing at all of them (sequentially, of course), the color sensitivity measurement obtained from such a stimulus is more likely to be accurate (or have a higher confidence score). One or more of these regions or tables may disappear and then reappear elsewhere as part of a moving stimulus, and the user's gaze thereon is tracked and interpreted to determine the color vision score.

[0025] In another aspect, if there are multiple such regions simultaneously appearing in various locations within the user's field of view, all of the regions will change color or intensity over time, and a blob containing another one of the regions will change color or intensity relative to the remaining background according to a target or desired color scheme. The blob moves around the user's field of view, and the user is instructed to find and follow the blob that is a different color from the background. FIG. 6 is a flow diagram of such a method for color vision testing in which a motion stimulus is displayed to a user. The method may be performed by a processor of a color vision system such as that described above, having a non-visible light-based eye-tracking subsystem that generates tracking data for the user's left and right eyes, and a visible light display for displaying the motion stimulus simultaneously in the left eye's field of view, the right eye's field of view, or both the left and right eyes' fields of view. In this method, the processor is configured to signal the visible light display to display the motion stimulus as multiple PIPs (in the left eye's field of view, the right eye's field of view, or both the left and right eyes' fields of view simultaneously), each PIP containing a hidden figure moving within the respective PIP (operation 61). The PIP obscures the shape in the sense that an individual with color vision deficiency cannot see or fixate on it. In act 63, the processor uses tracking data from the eye tracking subsystem to record the tracked movement of the right eye or the tracked movement of the left eye as the right eye or the left eye moves while the motion stimulus is displayed in act 61, and interprets the tracked movement to determine whether the user is fixating and following the shape. Acts 61-63i)-iii) may be repeated at least once, each time using a different motion stimulus (act 64). The processor then evaluates the interpreted tracked movement of act 63 to determine the user's color vision score (act 66).

[0026] In one version of the method described above in FIG. 5 or FIG. 6 , each PIP or each instance of a PIP has a bubble background, and the shapes within the PIP are blobs of one or more bubbles in the foreground. The blobs vary not only in hue but also in monochromatic intensity or color saturation from one PIP to the next. The bubble background pattern from one table to the next can be maintained spatially consistent within the user's field of view, providing a visual continuity that may make color vision testing more comfortable for the user. In another embodiment, the color intensity or saturation of the majority of all bubbles that make up each PIP is dithered from one PIP to the next. This can advantageously prevent hyperactivity artifacts. Such artifacts allow users to see pixel value changes in isolated areas that are actually below the general threshold of color perception. The intensity or color trajectory of the bubbles across multiple tables can be smoothed to give the impression of smoothly flowing bubbles rather than noisy, transient pauses.

[0027] The hidden shape can move smoothly. This continuity allows the user to experience a stress-free, intuitive, and smooth tracking task, rather than searching a field for a shape in a random area. This also allows for much easier analysis of eye-tracking data, since there are fewer uncorrelated search eye movements in the eyes of normally sighted individuals.

[0028] The contrast in a first color pair can be compared to the observed contrast in a second color pair or to monochromatic contrast. Testing both color and monochromatic contrasts in a similar test format helps describe the two on a common scale. In the Ishihara test, an area composed of multiple bubbles has a different hue range than the adjacent background. In a similar test for monochromatic contrast sensitivity, an area composed of multiple bubbles has a different value range than the adjacent background. Alternatively, two patterns can be tested against each other in a forced-choice test. That is, for example, the mean difference of a color bubble pattern moves in a different direction than the mean difference of a value pattern, and the contrast of each can be adjusted relative to the threshold. For example, a ball-shaped pattern coded with a hue limit might move in a clockwise direction, while another ball-shaped pattern coded with a value limit might move in a counterclockwise direction. User perception can be observed by requesting the user to follow an object they perceive as moving and observing their gaze with an eye tracker as a smooth pursuit task. Depending on the pattern traced by the user's gaze, color perception thresholds can be determined at various levels and types of color-to-amplitude contrast.

[0029] In one aspect, the motion stimulus has small bubbles of pseudo-random size, color, and intensity superimposed with colors and intensities that tend to be seen as different shapes depending on the user's relative color and intensity contrast sensitivity. Multiple motion patterns are occasionally superimposed, and they can track together for a short period of time and then diverge from each other. This forced choice in path branching precludes a preference for continued tracking of barely observable objects, while higher contrast objects may exist elsewhere in the field that do not currently capture the user's attention. The pseudo-random motion path or display speed prevents erroneous measurements of contrast perception that may be achieved by continuing along a previously traced path with higher contrast along a fixed pattern. Superimposed temporal noise in the size, color, and intensity of each bubble can be added to mask hyperparaity effects, which may not represent the user's true color contrast perception.

[0030] In another version of the method described above in Figure 5 or Figure 6, each of the PIPs has a bubble background and the shapes are one or more bubble blobs in the foreground, and in some of the PIPs the blobs have a different hue range than the background and in some other of the PIPs the blobs have a different brightness or value range than the background.

[0031] In yet another version of the method of Figure 5 or 6, each PIP has a background of bubbles, and the graphic consists of at least one or more first blobs of bubbles and one or more second blobs of bubbles, where the first blobs have a different hue range than the background, the second blobs have a different brightness or value range than the background, and the first blobs appear to move in a different direction than the second blobs.

[0032] In yet another version of the method of FIG. 5 or FIG. 6 , the processor is further configured to signal the visible light display to display a horizontally moving set of vertical contrast stripes simultaneously with the motion stimulus in operation 61. The processor evaluates the tracked movement of the user's eyes in operation 63 to determine whether the user is misusing the system. In this regard, a wide background in the user's field of view that appears to be moving horizontally may distract the user from consciously following specific portions of the motion stimulus pattern, but it may be impossible for the user's eyes not to zigzag in an attempt to stabilize the pattern. Such a pattern may be particularly useful for eliminating the possibility of misusing the test. In this case, presenting a set of horizontally moving vertical contrast stripes may be useful by itself or in combination with other stimuli described herein. In this case, it may also be useful to reduce or eliminate the high spatial frequency contrast provided by the bubbles, which may allow the user to fixate their gaze on a specific bubble. On the other hand, such artificial fixations at a single point should be very easily detectable and may be a particularly useful "cue" for someone attempting to misuse the system to achieve a negative outcome.

[0033] A similar inspection strategy may be used to inspect low spatial frequency intensity contrast.

[0034] In another aspect of the present disclosure, the color vision test has a dynamic number of iterations, rather than a predetermined or fixed number. For example, referring to the example of FIG. 2A , where each iteration is a single pass through acts 13-18, a dynamic version of the test may perform a different number of such iterations when the processor determines that the test is complete or terminated. For example, each time the test is administered to a different person, or to the same person at various times, the processor may calculate a confidence score that may be updated after each iteration. The confidence score may refer to a level of certainty or reliability associated with the user's seen / not seen responses. The test may begin with the processor accessing a priori assumptions about the user's color contrast sensitivity (e.g., a probability distribution based on a normal distribution or a uniform distribution of all contrast sensitivities). The processor then questions the user about each presented PIP stimulus that usefully segments the current estimate with seen / not seen responses. There is a likelihood function associated with each answer to a particular question that the processor has access to. For example, regardless of any prior knowledge, if a user answers a particular question correctly, there is a probability distribution of contrast sensitivity (accessible to the processor), and if the user answers incorrectly, there is a different probability distribution. After each presentation and response, the processor calculates an updated probability distribution of the user's color contrast sensitivity by multiplying the pre-question (previous) probability distribution function by the answer likelihood function. The processor stops presenting the stimuli when the patient's sensitivity is found to be within a preset confidence limit, for example, when the standard deviation of the probability distribution function falls below a fixed value. Alternatively, the processor can present a monotonic staircase of contrast sensitivity questions. In a contrast-weakening staircase approach, a stopping criterion is met when the user fails a certain set of questions. The user's color contrast sensitivity is estimated at a level between a level at which the user can reliably pass the questions and a level at which the user will reliably fail the questions, for example, an estimate that the user has a 50% chance of passing the questions.

[0035] In one version of the color vision system described above, the processor may be external to the VR headset 1, which has a wired or wireless communication network interface through which tracking data from the eye tracking subsystem 8 is transmitted to the processor. An alternative to such a system is where the processor is integrated into the housing of the VR headset 1, or where the processor-implemented operations of the flow diagrams described above are distributed between different processors within the VR headset 1 and the external computing device 9.

[0036] In one embodiment, the eye tracking subsystem 8 is an infrared pupil tracking subsystem that generates images of the left and right eye pupils. In that case, the eye tracking subsystem 8 may image the entire left eye and the entire right eye, and the processor determines the gaze angles of the left and right eyes based on knowledge of the distance between the right and left visible light displays, the distance between the right eye and the right visible display, and the location of the left pupil in the left eye and the right pupil in the right eye, or the interpupillary distance.

[0037] In one aspect, the VR headset 1 has one or more light sensors that can be used to detect light levels inside the left and right compartments, and the processor is configured to record the light levels in the left and right compartments, representing the contribution of external light while the user is wearing the VR headset 1. To avoid affecting the results of the test in a non-repeatable manner, and thereby making the test more reliable, the processor controls parameters of the display (left display 3 or right display 4) to ensure that the lighting within the compartment (left compartment 5 or right compartment 6, respectively), or the chromaticity of the display, is consistent each time the color vision test is administered. The parameters depend on the color palette of the display and the nature of the lighting within the compartment.

[0038] Based on the above explanation, the following description of the present invention may be made. 15. A color vision testing system comprising: a non-visible light based eye tracking subsystem that generates tracking data for the user's left or right eye; a processor, wherein the processor: i) signaling a visible light display to display a motion stimulus in the left eye's field of view, the right eye's field of view, or both the left and right eye's fields of view simultaneously, the motion stimulus including a background and a region that contrasts in color with the background, the region changing position relative to the rest of the motion stimulus to form a pattern; ii) using tracking data from the eye-tracking subsystem to record the tracked position of the right eye or the tracked position of the left eye as the right eye or the left eye moves while the motion stimulus is displayed in i); iii) interpreting the tracked movements to determine whether the user is gaze-gaze following a pattern; iv) A system configured to repeat steps i) to iii) multiple times using different motor stimuli each time. 16. The system of statement 15, wherein the processor is further configured to evaluate iii)-iv) to determine the user's color vision score. 17. The system of any one of statements 15 to 16, wherein the display is a desktop display screen and the eye-tracking subsystem is mountable on the desktop display screen. 18. The system of any one of statements 15 to 16, wherein the display is a display screen integrated into the housing of the tablet computer, and the eye tracking subsystem is integrated into the housing of the tablet computer. 19. The system of any one of statements 15 to 16, wherein the display and eye-tracking subsystem are attached to or form part of a virtual reality headset. 20. A color vision testing system comprising: a non-visible light based eye tracking subsystem that generates tracking data for the user's left or right eye; a processor, wherein the processor: i) signaling a visible light display to display a motion stimulus in the left eye's field of view, the right eye's field of view, or both the left and right eye's fields of view simultaneously, the motion stimulus comprising a pseudoisochromat (PIP), and a moving figure hidden within the PIP; ii) using tracking data from the eye-tracking subsystem to record tracked movements of the right eye or tracked movements of the left eye when the right eye or left eye moves while the motion stimulus is displayed in i); iii) interpreting the tracked movement to determine whether the user is gaze-gaze-tracking the shape within the PIP; iv) Repeat steps i) to iii) at least once using a different motor stimulus each time. v) A system configured to evaluate iii) to iv) to determine the user's color vision score. 21. The system of claim 20, wherein each of the PIPs includes a bubble background, the shapes are blobs of one or more bubbles in the foreground, and the blobs vary in hue and monochrome intensity or color saturation from one PIP to the next. 22. The system of statement 21, wherein the color intensity or saturation of the majority of all bubbles that make up each PIP is dithered from one PIP to the next. 23. The system of claim 20, wherein each of the PIPs has a bubble background and the shapes are one or more bubble blobs in the foreground, and in some of the PIPs the blobs have a different hue range than the background, and in some other of the PIPs the blobs have a different brightness or value range than the background. 24. The system of claim 20, wherein each of the PIPs includes a background of bubbles, the figure includes one or more first blobs of bubbles and one or more second blobs of bubbles, the first blobs having a different hue range than the background, the second blobs having a different brightness or value range than the background, and the first blobs appear to move in a different direction than the second blobs. 25. The system of statement 20, wherein the processor is further configured in i) to signal the visible light display to display a horizontally moving set of vertically contrasting stripes simultaneously with the motion stimulus, and to evaluate the tracked movement to determine whether the user is misusing the system.

[0039] While particular embodiments have been described and shown in the accompanying drawings, it will be understood that these are merely illustrative of the broad invention and not limiting, and since various other modifications may occur to those skilled in the art, the invention is not limited to the specific constructions and arrangements shown and described. Accordingly, this description is to be regarded as illustrative rather than limiting.

Claims

1. 1. A stereoscopic system comprising: a VR headset comprising: a left visible light display, a left compartment for wearing over a user's left eye, a right visible light display, and a right compartment for wearing over the user's right eye, the left and right compartments configured such that when the headset is worn over the user's eyes, a) the user cannot see the right display using only their left eye, and b) the user cannot see the left display using only their right eye; and a non-visible light based eye tracking subsystem that generates tracking data for the left and right eyes; a processor, wherein when the headset is placed on the user's eyes, the processor: i) signaling the left visible light display or the right visible light display to simultaneously display i) a pseudoisochromat (PIP) for color vision testing and ii) a plurality of user-selectable graphics; ii) using the tracking data from the eye tracking subsystem to record a tracked position of the right eye or the left eye as the right eye or the left eye moves while the PIP is presented in i); iii) interpreting the tracked position of the right eye or the left eye to determine a user-selectable shape selected by the user from among the plurality of user-selectable shapes; iv) the system is configured to record an indication as to whether the user viewed the stimulus graphic based on a comparison of the stimulus graphic in the PIP with the user-selectable graphic.

2. 10. The system of claim 1, wherein the processor controls parameters of the left or right display to ensure that lighting in the left or right compartment or chromaticity of the left or right display does not affect the results of the test in a non-repeatable manner.

3. 10. The system of claim 1, wherein the processor executes steps i)-iv) multiple times, each time the PIP includes a different stimulus graphic, and records multiple indicators of whether the user viewed the stimulus graphic.

4. The processor, when the headset is placed on the user's eyes, i) sending a signal to the left visible light display or the right visible light display to display a second PIP for the color vision test, the second PIP including a second stimulus figure, the second stimulus figure including an elongated mark branching at a bifurcation point; ii) using the tracking data from the eye tracking subsystem to record tracked movements of the right eye or the left eye as the right eye or the left eye moves while the second PIP is shown; iii) interpreting the tracked movement of the right eye or the left eye as being along the elongate mark; iv) recording an indication as to whether the user looked at the second stimulus graphic based on interpreting the tracked movement as indicating hesitation by the user at the bifurcation point.

5. The system of claim 4 , wherein the processor is configured to quantify the hesitation and use the hesitation to provide more information than simply a binary right or wrong.

6. The system of claim 1 , wherein the processor completes the test for the user without receiving manual input from the user as to whether the user viewed the stimulus graphic.

7. 7. The system of claim 6, wherein the processor is further configured to interpret tracking data of the eye tracking subsystem to detect a blink by the user while the PIP table is displayed in i), and determine a user-selected shape based on the detected blink.

8. 2. The system of claim 1, wherein the processor executes steps i) to iv) multiple times, each time the display of the PIP alternates between the left visible light display and the right visible light display in i), and wherein in iv), the indication as to whether the user saw the stimulus graphic in the PIP refers to only the left eye or only the right eye.

9. 9. The system of claim 1, wherein the processor is external to the VR headset, and the VR headset includes a wired or wireless communication network interface through which the tracking data from the eye tracking subsystem is transmitted to the processor.

10. The system of any one of claims 1 to 9, wherein the eye-tracking subsystem is an infrared pupil-tracking subsystem that generates images of the pupils of the left and right eyes.

11. The eye tracking subsystem images the entire left eye and the entire right eye, and the processor: knowledge of the distance between the right visible light display and the left visible light display; the distance between the right eye and the right visible display; 11. The system of claim 1, further comprising: determining the gaze angle of the left eye and the right eye based on the location of the left pupil in the left eye and the right pupil in the right eye, or the interpupillary distance.

12. 12. The system of claim 1, wherein the VR headset comprises one or more light sensors that can be used to detect light levels inside the left and right compartments, and the processor is configured to record the light levels in the left and right compartments, representing the contribution of external light while the user is wearing the VR headset.

13. 1. A stereoscopic system, comprising: A VR headset, a left visible light display; a left compartment for wearing over the user's left eye; a right visible light display; a right compartment for the user's right eye, the left compartment and the right compartment being configured such that when the headset is worn on the user's eye, 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; and a non-visible light based eye tracking subsystem that generates tracking data for the left eye and the right eye; a processor, wherein when the headset is placed on the user's eyes, the processor: i) signaling the left visible light display or the right visible light display to display a sequence of a plurality of tables for a constellation-type color vision test; ii) using the tracking data from the eye tracking subsystem to record tracked movements of the right eye or the left eye as the right eye or the left eye moves while the sequence in i) is displayed; iii) a) picking up a selected table of the plurality of tables, then b) dragging the selected table to a different position in the sequence, and then c) interpreting the tracked movement or detecting a blink of the right eye or the left eye as placing the selected table at the different position; iv) repeating iii) a plurality of times to result in a reordered sequence of said plurality of tables; v) a system configured to evaluate the rearranged sequence to determine a color vision score for the user.

14. 14. The system of claim 13, wherein for a) and c), the processor interprets the tracked movement of the right eye or the left eye as the user gazing at the selected table.

15. 1. A method for color vision testing, comprising: i) signaling a left visible light display or a right visible light display to simultaneously display i) a pseudoisochromat (PIP) for color vision testing and ii) a plurality of user-selectable graphics; ii) using tracking data from an eye tracking subsystem to record a tracked position of the right eye or the left eye as the right eye or the left eye moves while the PIP is presented in i); and iii) interpreting the tracked position of the right eye or the left eye to determine a selected user selectable shape from among the plurality of user selectable shapes; iv) recording an indication as to whether the user viewed the stimulus graphic based on a comparison of the stimulus graphic in the PIP with the user-selectable graphic.

16. sending a signal to the left visible light display or the right visible light display to display a second PIP for the color vision test, the second PIP including a second stimulus figure, the second stimulus figure including an elongated mark branching at a bifurcation point; using the tracking data from the eye tracking subsystem to record tracked movements of the right eye or the left eye as the right eye or the left eye moves while the second PIP is shown; interpreting the tracked movement of the right eye or the left eye as being along the elongate mark; 16. The method of claim 15, further comprising: recording an indication as to whether the user looked at the second stimulus graphic based on interpreting the tracked movement as indicating hesitation by the user at the bifurcation point.

17. 17. The method of claim 16, further comprising quantifying the hesitation and using the hesitation to provide more information than simply a binary right or wrong.

18. 16. The method of claim 15, wherein the color vision test for the user is completed without receiving manual input from the user as to whether the user has seen the stimulus graphic.

19. 16. The method of claim 15, further comprising interpreting tracking data of the eye tracking subsystem to detect a blink by the user while the PIP table is displayed in i), and determining a user-selected shape based on the detected blink.

20. 16. The method of claim 15, further comprising performing steps i)-iv) a plurality of times, each time the display of the PIP alternates between the left visible light display and the right visible light display in i), and wherein in iv), the indication as to whether the user saw the stimulus graphic in the PIP refers to only the left eye or only the right eye.

21. 1. A color vision testing system comprising: a processor, the processor comprising: i) accessing prior assumptions of color contrast sensitivity; ii) signaling a visible light display to present stimuli within the user's visual field in accordance with the color contrast sensitivity a priori assumptions, the stimuli including pseudoisochromats (PIPs), and recording the user's responses while the stimuli are presented; iii) repeating ii) a plurality of times, thereby obtaining a plurality of responses of the user to the plurality of presented stimuli; iv) interpreting the user's responses into answers; v) for each of the plurality of answers, accessing a first likelihood function if the answer is correct and a different second likelihood function if the answer is incorrect; vi) after each presentation and response, calculating an updated probability distribution of the user's color contrast sensitivity based on the previous probability distribution and based on the accessed first likelihood function or the second likelihood function; vii) the system is configured to discontinue presentation of the stimuli when the updated probability distribution is found to have a preset confidence limit.

22. 22. The system of claim 21, wherein the processor is further configured to, in response to ceasing presentation of the stimuli, determine a color vision score for the user based on the updated probability distribution.

23. A method for color vision testing, i) sending a signal to a left visible light display or a right visible light display to display a sequence of a plurality of tables for a constellation color vision test; ii) using tracking data from an eye tracking subsystem to record tracked movements of the user's right eye or left eye as the eye moves while the sequence in i) is displayed; and iii) a) picking up a selected table of the plurality of tables, then b) dragging the selected table to a different position in the sequence, and then c) interpreting the tracked movement to detect a blink of the right eye or the left eye with the selected table at the different position; iv) repeating iii) a plurality of times to result in a reordered sequence of said plurality of tables; and v) evaluating the rearranged sequence to determine a color vision score for the user.

24. 24. The method of claim 23, wherein for a) and c), the tracked movement of the right eye or the left eye is interpreted as the user gazing at the selected table.

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