Patent Description:
<NPL>, describes that in recent years it has been shown that it is of considerable clinical value to determine the visual contrast sensitivity function of the patient. They describe an approach which exploits electrophysiological techniques using the visual evoked cortical potential (VECP) to checkerboard onset-offset stimulation. Its application in a variety of disorders of the visual system is described. The importance of selecting the most appropriate stimulus parameters is discussed, and the relative advantages and disadvantages as compared with psychophysical methods are appraised.

<NPL> describes that the contrast sensitivity function (CSF) is an informative measure of visual function, but current tools for assessing it are limited by the attentional, motor, and communicative abilities of the participant. Impairments in these abilities can prevent participants from engaging with tasks or following an experimenter's instructions. They particularly describe an efficient new tool for measuring contrast sensitivity, Curveball, and empirically validate it with a sample of healthy adults. The Curveball algorithm continuously infers stimulus visibility through smooth eye tracking instead of perceptual report, and rapidly lowers stimulus contrast in real time until a threshold is found. The procedure requires minimal instruction to administer and takes only five minutes to estimate a full CSF, which is comparable to the best existing methods available for healthy adults. Task repeatability was high. They also present evidence that the task is robust across illumination changes, well correlated with results from conventional psychophysical methods, and highly sensitive to improvements in visual acuity from refractive correction. Their findings indicate that Curveball is a promising means of accurately assessing contrast sensitivity in previously neglected populations.

<NPL> describes that microsaccades are small rapid and involuntary eye movements that occur during fixation in an apparently stochastic manner. They are known to be inhibited in response to sensory transients, with a time course that depends on the stimulus parameters and attention. However, the time-related precision of their onsets and the degree to which they can be used to assess the response of the visual system to basic stimulus parameters is currently unknown. In the publication they studied microsaccade response properties as a function of the contrast and spatial frequency of visual onsets. Observers viewed and silently counted <NUM>-min sequences of Gabor patches presented briefly (<NUM>) at <NUM>. Contrast and spatial frequency were randomized in different experiments. They found that the microsaccade response time, as measured by the latency of the first microsaccade relative to stimulus onset following its release from inhibition, was sensitive to the contrast and spatial frequency of the stimulus and could be used to extract a contrast response function without the observers' response. They also found that contrast detection thresholds, measured behaviorally for different spatial frequencies, were highly and positively correlated with the microsaccade response time measured at high contrast (><NUM> times the threshold).

<NPL> describes that measuring the contrast sensitivity function (CSF) in the periphery of the eye is complicated. The lengthy measurement time precludes all but the most determined subjects. The aim of this study was to implement and evaluate a faster routine based on the quick CSF method (qCSF) but adapted to work in the periphery. Additionally, normative data is presented on neurally limited peripheral CSFs. A peripheral qCSF measurement using <NUM> trials can be performed in <NUM>. The precision and accuracy were tested for three subjects under different conditions (number of trials, peripheral angles, and optical corrections). In the second part of the study, they collected three CSFs of <NUM> trials for six persons in the <NUM> nasal, temporal, inferior, and superior visual fields. The measurements were performed in an adaptive optics system running in a continuous closed loop. Contrast sensitivity was higher in the horizontal fields, and the inferior field was better than the superior. This modified qCSF method decreases the measurement time significantly and allows otherwise unfeasible studies of the peripheral CSF.

<CIT> discloses a method, a device and a computer program for determining a refractive error of an eye of a user, and a method of for manufacturing a spectacle lens for the eye of the user. The method for determining a refractive error of an eye of a user comprises the following steps: a) displaying a feature on a screen, wherein a parameter of the feature displayed on the screen is varied; b) acquiring an eye movement metric of the eye of the user as a function of the feature displayed on the screen; c) determining a time at which the eye movement metric of the eye of the user is used to determine a detection threshold of the refractive error of the eye of the user; d) determining a value for the refractive error of the eye of the user from the parameter determined at the time. A visual fixation mark is not displayed.

<CIT> discloses an apparatus, software and methods for assessing ocular, ophthalmic, neurological, physiological, psychological and/or behavioral conditions. As disclosed herein, the conditions are assessed using eye-tracking technology that beneficially eliminates the need for a subject to fixate and maintain focus during testing or to produce a secondary (non-optical) physical movement or audible response, i.e., feedback. The subject is only required to look at a series of individual visual stimuli, which is generally an involuntary reaction. The reduced need for cognitive and/or physical involvement of a subject allows the present modalities to achieve greater accuracy, due to reduced human error, and to be used with a wide variety of subjects, including small children, patients with physical disabilities or injuries, patients with diminished mental capacity, elderly patients, animals, etc. A visual fixation mark is not displayed.

<CIT> discloses a visual acuity testing system that includes a computer with a high-resolution display linked to a video camera. Vertical gratings of varying width are presented either side of a central target image or video, coincident with an iso-luminant image opposite the grating. A digital video camera adjacent to the display is employed to track eye position using software algorithms that relate eye movement to the position of the vertical grating. Software analysis adjusts for head movement, blinks and corneal reflexes. The system eliminates the need to lift acuity cards manually, and provides an automated and objective method of vision assessment in pre-verbal children and those unable to communicate in standard visual acuity tests. The appearance of the vertical grating is not time-varying.

<CIT> discloses a perimeter or a campimeter with a visible fixation point and a method used in them. The method comprises at least the following steps: producing a fixation point having a first visual appearance to be shown to a patient; producing a stimulus shown to the patient at a stimulus time-point at a pre-defined location; activating a response device by the patient upon noticing the stimulus at a response time-point; changing the fixation point to have a second visual appearance for a fixation point second visual appearance time interval near the stimulus time-point.

<CIT> discloses that, in certain embodiments, vision defect information may be generated via a dynamic eye-characteristic-based fixation point. In some embodiments, a first stimulus may be displayed at a first location on a user interface based on a fixation point for a visual test presentation. The fixation point for the visual test presentation may be adjusted during the visual test presentation based on eye characteristic information related to a user. As an example, the eye characteristic information may indicate a characteristic of an eye of the user that occurred during the visual test presentation. A second stimulus may be displayed during the visual test presentation at a second interface location on the user interface based on the adjusted fixation point for the visual test presentation. Vision defect information associated with the user may be generated based on feedback information indicating feedback related to the first stimulus and feedback related to the second stimulus.

<CIT> discloses methods and systems for assessing a visual field of a person. Information can be presented to a person undergoing a visual field testing in a manner that utilizes the person's natural tendency to look at an object that is displayed so that it attracts the person's attention. A fixation target can be displayed on a display viewed by a user. Once it is determined that the user has viewed the fixation target and the person's eye(s) location is determined, a test target is displayed on the display in a location corresponding to a location on the user's visual field. The test target is determined to be either detected or missed based on user input acquired as the user is viewing the display.

<CIT> that, in certain embodiments, enhancement of a field of view of a user may be facilitated via one or more dynamic display portions. In some embodiments, one or more changes related to one or more eyes of a user may be monitored. Based on the monitoring, one or more positions of one or more transparent display portions of a screen of wearable device may be adjusted, where the transparent display portions enable the user to see through the screen of the wearable device. A live video stream representing an environment of the user may be obtained via the wearable device. An enhanced video stream derived from the live video stream may be displayed on one or more other display portions of the screen of the wearable device.

It is therefore an objective of the present invention, in particular in view of <CIT>, to provide to a computer-implemented method, a computer program and an apparatus for determining at least one visual performance of at least one eye of a person, which at least partially overcome the problems of the state of the art.

It is a particular objective of the present invention, to provide a reliable and efficient approach to examine a complex visual performance of a patient's peripheral field of view in an automatic examination process for a plurality of defined points in a visual field area. It is further object of the invention to monitor a time dependency of the visual field.

This problem is solved by a method, a computer-implemented method, a computer program and an apparatus for determining at least one visual performance of at least one eye of a person having the features of the independent claims. Preferred embodiments, which can be implemented in an isolated fashion or in any arbitrary combination, are listed in the dependent claims or throughout the following description.

In a first aspect, the present invention relates to a computer-implemented method for determining at least one visual performance of at least one eye of a person, wherein the method comprises at least the following steps:.

wherein the at least one visual performance of the at least one eye of the person is determined for at least one point in a visual field of the person by using a first spatial location of the at least one visual fixation mark and a second spatial location of the at least one visual stimulus; wherein an attention level of the person is determined by evaluating a time-related difference in the reaction times between the at least one particular measurement cycle and the at least one subsequent measurement cycle.

As generally used, the term "computer-implemented method" refers to a method which involves a programmable apparatus, in particular, a computer, a computer network, a processing device, such as comprised by a mobile communication device, or a readable medium carrying a program, whereby at least one of the steps of the method, specifically at least one of steps a), b), c) and/or d), are performed by using at least one computer program. Alternatively, the at least one computer program may be accessible by an apparatus which may be adapted for performing the method via a network, such as via an in-house network or via internet. With particular regard to the present invention, the present method can, thus, be performed on a programmable apparatus, which is configured for this purpose, such as by providing a computer program which is configured for such a purpose.

As generally used, the term "determine" or any grammatical variation thereof refers to a process of generating representative results which are, typically, denoted as "data". With particular regard to the present invention, the data comprise information, which are related to the at least one visual performance within a visual field of at least one eye of a person.

As further used herein, the term "visual performance" refers to a property at least indirectly and/or directly related to a performance of the at least one eye of the person which can be determined by investigating the at least one eye of the person by an adapted measurement procedure.

According to step a), to at least one eye of a person at least one visual fixation mark configured to attract a visual perception of the person by directing a line of sight of the at least one eye of the person towards the visual fixation mark is displayed on a screen. The at least one visual fixation mark may be presented visually to the at least one eye of the person, particularly in a perceivable manner.

As generally used, the term "displaying" or any grammatical deviation thereof refers to a presentation of at least one of an image, an item, text, or a video, particularly at least one of a visual fixation mark or a visual stimulus, on the at least one screen.

As generally used, the term "screen" refers to an electronic visual display device designated for the presentation of at least one of an image, an item, text, or a video transmitted electronically. With particular regard to the present invention, the screen may be configured for displaying the at least one visual fixation mark to the at least one eye of a person, particularly in such manner that the at least one visual fixation mark may be perceptible by the at least one eye of the person. The at least one visual fixation mark may also be displayed to be perceptible by both eyes of the person.

As used herein, the term "visual fixation mark" refers to an item configured to attract a visual perception of the person by directing a line of sight of the at least one eye of the person towards the visual fixation mark. The person is, particularly, attracted to fixate the visual fixation mark in such a manner that a line of sight of the at least one eye of the person intersects with the visual fixation mark for at least a predetermined time interval. Based on standard ISO <NUM>:<NUM>, Section <NUM>. <NUM>, the term "line of sight" refers to an path from a point of interest, i.e. a point of fixation, in object space to a center of an entrance pupil of the eye of the person and, further, comprise a continuation in image space from a center of an exit pupil to a retinal point of fixation, generally the foveola, in the eye of the person.

According to step b), subsequently to the at least one eye of the person at least one visual stimulus configured to elicit at least one eye movement in the at least one eye of the person towards the at least one visual stimulus is displayed on the screen. The at least one visual stimulus may be presented in a manner that it is perceptible by the at least one eye of the person. This may elicit the at least one eye movement. An eye movement elicited by the at least one visual stimulus may be an eye movement according to which the line of sight and/or the gaze position of the at least one eye of the person is directed towards the at least one visual stimulus. The at least one visual fixation mark may be presented on a first sub-screen and the at least one visual stimulus may be presented on at least one second sub-screen.

As used herein, the term "visual stimulus" refers to a graphical presentation of an item, which is known or reasonably to be expected by the person skilled in the art to elicit the at least one desired type of eye movements in the at least one eye of the person. The at least one visual stimulus may be displayed at a spatial location on the screen that is different from the spatial location on the screen of the at least one fixation mark.

As generally used, the term "eliciting" or any grammatical deviation thereof refers to purpose of the displayed item, particularly the at least one visual stimulus and/or at least one fixation mark, namely the purpose to induce at least one eye movement of the person. The term "eye movement" refers to a time-variance of the line of sight and/or the gaze position of the at least one eye. The at least one eye movement that may be relevant for the present invention, is the eye movement from the at least one visual fixation mark to the at least one visual stimulus, or vice versa. This eye movement causes the line of sight of the at least one eye of the person to change from intersecting the at least one visual fixation mark to intersecting the at least one visual stimulus, or vice versa.

A sequence of step a) and b) causes the at least one eye of the person to i) fixate the at least one visual fixation target and then ii) fixate the at least one visual stimulus. A further sequence of step a) and b) causes the at least one eye of the person to iii) fixate the at least one visual fixation target again and then ii) fixate the at least one visual stimulus again. This eye movement may be induced by a different spatial location of the at least one visual fixation mark and the at least one visual stimulus.

According to step c), tracking data about the at least one eye movement of the at least one eye of the person by using at least one eye-tracking device is generated, particularly tracking data about the at least one eye movement of the at least one eye of the person moving towards the at least one visual stimulus by using at least one eye-tracking device is generated.

As generally used, the term "tracking" or any grammatical deviation thereof refers to recording motions of the at least one eye by using the at least one eye-tracking device. As generally used, the term "eye-tracking device" refers to a device that is used to record the motion of the at least one eye of the person, particularly a change of the line of sight and/or a gaze position of the at least one eye of the person. As a result of the recording, eye tracking data comprising information about the motion of the at least one eye of the person is generated, wherein the information about the motion of the at least one eye of the person may be given by the time-variance of the line of sight and/or the gaze position of the at least one eye. At least one outcome may be provided comprising the tracking data.

According to step d), the at least one visual performance from the tracking data is determined by using at least one processing device. The term "processing device" refers to at least one and/or a plurality of components of a computer system designated to process data, particularly process input data to generate output data. The tracking data may be considered as input data.

In accordance with the present invention, the at least one visual performance of the at least one eye of the person is determined for at least one point, preferably a plurality of points, in the visual field of the person by further using at least a first spatial location of the at least one visual fixation mark and a second spatial location of the at least one visual stimulus during step d). As generally used, the term "visual field" refers to a spatial area which is perceptible by the at least one eye of the person. The second spatial location of the at least one visual stimulus on the screen may be assigned to a particular point in the visual field using an assignment rule. As generally used, the term "assignment rule" refers to a relationship between two parameters, especially between the second spatial location of the at least one visual stimulus on the screen and the particular point in the visual field.

Further in accordance with the present invention, an attention level of the person is determined by evaluating a time-related difference in the reaction times between the at least one particular measurement cycle and the at least one subsequent measurement cycle. As used herein, the term "time-related difference" refers to a value of a deviation between the reaction time recorded in the particular measurement cycle and the reaction time recorded in the subsequent measurement cycle. The term "subsequent measurement cycle", refers to a measurement cycle, which is performed at a point in time that is later than the point in time at which the particular measurement cycle was performed. As used herein, the term "attention level" refers to a score of the awareness of the person, particularly the degree of awareness to perceive a visual stimulus. A visual stimulus may be considered as perceived when to person is aware of a presence of the visual stimulus. It is not necessary to identify a visual stimulus for being aware of it.

The attention level may be determined spatially resolved, particularly in the visual field of the person. The attention level may be determined spatially resolved for a plurality of different points in the visual field of the person. Particularly therefore, the at least one time-related difference in the reaction times may be determined for at least one specific point. Alternatively, a plurality of time-related difference may be determined for a plurality of different points in the visual field of the person. Thereby, a map of the visual field may be generated, wherein the map comprises a plurality of time-related differences in reaction times, wherein each time-related difference in reaction times is related to a different point in the field of view. A size of the at least one visual stimulus being during any measurement cycle may remain.

In a particularly preferred embodiment, the at least one visual performance may be determined for a particular point in the visual field by assigning a particular spatial location to the particular point using an assignment rule. In a particularly preferred embodiment, the assignment rule considers the second spatial location of the at least one visual stimulus and the first spatial location of the at least one visual fixation mark; and particularly further considers a distance between the at least one eye of the person and the at least one visual stimulus and/or the at least one visual fixation mark.

In a preferred embodiment, the first spatial location of the at least one visual fixation mark may be recorded during step a) and the second spatial location of the at least one visual stimulus may be recorded during step b). As used herein, the term "spatial location" refers to a specific position of the at least one respective item on the screen. As further used herein, the terms "first" and "second" are designed to distinguish the same kind of parameters, however, related to two different items. The item may be the at least one visual fixation mark and/or the at least one visual stimulus. In particular, the spatial location of an item may be recorded by using a signal which is configured for displaying the item on the at least one screen. As further used herein, the term "recording" or any grammatical variation thereof refers to producing data comprising information about the spatial location of the least one respective item and making the data available to the method.

The first spatial location of the at least one visual fixation mark may be recorded during step a). Further, the distance between the at least one eye of the person and the at least one visual stimulus and/or the at least one visual fixation mark may be recorded using a distance measuring device.

In a particularly preferred embodiment, a measurement cycle may comprise at least step b) and step c), more particular the measurement cycle may, additionally, comprise step a) and/or step d), wherein at least two measurement cycles, preferably a plurality of measurement cycles, may be performed for determining a plurality of points in the visual field, specifically with a differing second spatial location of the at least one visual stimulus. In particular, the differing second spatial locations may have different eccentricity levels and/or a spatial orientations with regard to the at least one visual fixation mark. As used herein, the term "eccentricity level" refers to an absolute value of the vector connecting the at least one visual stimulus and the at least one fixation mark. The term "spatial orientation" refers to the direction of a vector connecting the second spatial location of the at least one visual stimulus and the first spatial location of the at least one fixation mark. As used herein, the term "plurality" refers to a quantity of at least two items.

In a particularly preferred embodiment, assigning the particular point in the visual field to the particular spatial location may be performed using an assignment rule, wherein the assignment rule may be maintained during the at least two measurement cycles and/or in all measurement cycles. The term "measurement cycle" refers herein to a sequence of at least the steps b) and c), wherein step a) and/or step d) may, additionally, be comprised by the measurement cycle. In a preferred embodiment, at least one of: <NUM>; <NUM>; <NUM>; <NUM>; <NUM>; <NUM>; <NUM>; <NUM>; <NUM>; <NUM>; <NUM> or <NUM> cycles may be performed.

In a particularly preferred embodiment, the at least one visual fixation mark may be displayed in a center area of the screen, particularly directing the at least one eye of the person in a neutral position. The neutral position may be the primary position of the eye. In the primary position, the eye is looking straight ahead with a visual axis parallel to a sagittal plane of the head of the person.

In a particularly preferred embodiment, the center area may be completely enclosed by a surrounding area, wherein the at least one visual stimulus is displayed in the surrounding area in step b). As generally used, the term "completely enclosed" refers to the fact that the center area is delimited around its entire perimeter by the surrounding area.

In a particularly preferred embodiment, an angle α may be given between a first connecting line and a second connecting line, wherein the first connecting line connects a center of the at least one visual fixation mark and at least one reference position in the at least one eye of the person, wherein the second connecting line connects a center of the at least one visual stimulus and the at least one reference position in the at least one eye of the person, wherein α is larger than at least one of: <NUM>°, <NUM>°; <NUM>°; <NUM>°; <NUM> °; <NUM>°; or <NUM>°. Thereby, the at least one visual stimulus is perceivable to the at least one eye of the person in a peripheral field of view when the at least one eye is fixating the visual fixation mark. As generally used, the term "field of view" refers to the extent of the observable world that is seen be the at least one eye of the person.

In a particularly preferred embodiment, the at least one reference position in the at least one eye of the person may be selected from at least one of:.

As generally used, the term "corneal reflex" refers to a visible reflex on the cornea as generated by a light beam impinging on the eye. As further generally used, the term "corneal apex" refers to a most anterior point of a cornea when the at least one eye is in the primary position.

In a particularly preferred embodiment, the at least one visual stimulus can be display in any spatial orientation with regard to the at least one visual fixation mark. The term "spatial orientation" refers to the direction of a vector connecting the at least one visual stimulus and the at least one fixation mark.

In a particularly preferred embodiment, the surrounding area may correspond to the peripheral field of view, when the line of sight of the at least one eye of the person intersects with the at least one visual fixation mark. The term "peripheral field of view" is a portion of the field of view that comprises a vision occurring outside the gaze position. The line of sight is not comprised in the peripheral field of view. The peripheral field of view is outside of a central field of view.

In a particularly preferred embodiment, a third connecting line connecting an outer perimeter of the central field of view, particularly connecting a maximal circumference of the central field of view, and a reference position in the at least one eye of the person may be given, wherein a central field of view angle β between the third connecting line and the line of sight of the at least one eye of the person that intersects the reference position in the at least one eye of the person, is at least one of: <NUM>°, <NUM>°; <NUM>°; <NUM>°; <NUM> °; <NUM>° or <NUM>°. The term "central field of view" refers to a portion of the field of view comprising the line of sight. The central field of view is surrounded by the peripheral field of view, particularly directly surrounded.

In a particularly preferred embodiment, the at least one visual performance of the at least one eye may be selected from at least one of:.

As generally used, the term "contrast sensitivity" refers to a property of at least one eye of a person to discern between different luminance levels in at least one visual target. As further generally used, the term "visual acuity" refers to a spatial resolution ability of the at least one eye of the person with respect to a structure within at least one visual target. As further generally used, the term "color vision" refers to a property of the at least one eye of the person to discern between different colors comprised by at least one visual target. As generally used, the term "time-related sensitivity" refers to the ability of the person to perceive a visual stimulus dependent on the time varying appearance of the at least one visual stimulus. As used herein, the term "visual attention" refers to a degree of awareness of the person, particularly a degree of awareness to perceive a visual stimulus. The visual attention may be analyzed to determine a time-variance of the ability of the person to concentrate, particularly the ability of the person to concentrate on visual input, specifically the ability of the person to concentrate dependent on the visual field of the person.

In a preferred embodiment, the at least one eye movement may be a reflexive saccade in the at least one eye of the person. As generally used, the term "saccade" refers to a movement of the at least one eye of the person. Particularly a movement from the at least one fixation target to the at least one visual stimulus, or vice versa. The term "reflexive" refers to the fact that the person does not intend the eye movement. A reflexive saccade may be triggered by at least one of: an appearing of the at least one visual stimulus, a disappearing of the at least one a visual fixation mark, an appearing of the at least one a visual fixation mark, or a disappearing of the at least one a visual stimulus.

In a preferred embodiment, a pupil size of the at least one eye of the person may, further, be recorded, particularly a time-variance of the pupil size of the at least one eye of the person. As generally used, the term "pupil" refers to a black hole having the recorded size located in a center of an iris of the at least one eye of the person. By recording the pupil size, pupil size data may be generated comprising information about the pupil size, particularly information about an area, a diameter, or a radius of the pupil.

In a preferred embodiment, the at least one visual stimulus may be continuously displayed during step b). As used herein, the term "continuously" expresses that at least one visual stimulus is constantly displayed. The at least one visual stimulus is therefore not disappearing and appearing again during step b).

In a preferred embodiment, the at least one visual stimulus may be selected from at least one of:.

As used herein, the term "artificial pattern", as used herein, relates to a computer-generated pattern or to a pattern generated by a computer. The term "natural image" refers to a picture having been captured from a scene occurring in nature. By way of example, the natural image may be a picture of a landscape or of an interior scene, such as of a room or a part thereof. The term "virtual image" refers to a scene that was generated by using a computer program, preferably, in a fashion that it may resemble and/or reconstruct a naturally occurring scene. As further generally used, the term "grating" refers to a regularly spaced collection of identical, parallel, elongated elements. The term "Gabor patches" refers to sinusoidal gratings, usually with a Gaussian envelope, which are known to be particularly useful as visual stimulus for the user's eye. As generally used, the term "noise" refers to an interference quantity with a broad non-specific frequency spectrum. The noise patch is the visual presentation of this noise with the further requirement that the noise patch has at least one defined spatial frequency. As further generally used, the term "spatial frequency" refers to a reciprocal value of a spatial distance reflecting a spatial period of repetition in the at least one visual stimulus. The grating, the Gabor patch and/or the noise patch may specifically be artificial patterns.

In a preferred embodiment, an appearance of the at least one visual stimulus may be displayed in a time-varying manner on the at least one screen. As used herein, the term "appearance" refers to a look of the respective item, particularly the at least one visual stimulus and/or the at least one fixation mark. As used herein, the term "time-varying manner" refers to the fact that the appearance changes over time. Meaning that the appearance of the at least one visual stimulus is different at a first time from an appearance of the at least one visual stimulus at a second time. During time-varying the appearance, the at least one visual stimulus may be continuously displayed on the screen to the at least one eye of the person. The time-varying in the appearance of the at least one visual stimulus during step b) may thus be always perceivable by the at least one eye of the person.

In a preferred embodiment, an appearance of the at least one visual fixation mark on the at least one screen and the appearance of the at least one visual stimulus on the at least one screen may differ from each other. As the appearance of the at least one visual stimulus and the at least one fixation mark is different, the person may by visually inspecting these items tell which item the person is perceiving. The appearance may not to be confused with a spatial location.

In a preferred embodiment, the at least one visual fixation mark may be maintained in a constant manner during at least one measurement cycle, preferably a plurality of measurement cycles. As used herein, the term "constant" implies that the appearance and/or the first spatial location of the at least one visual fixation mark on the screen is not time-varying. In other words, the appearance and/or the first spatial location of the at least one visual fixation mark may, as particularly preferred, remain unchanged during it is displayed on the at least one screen, particularly during step a).

In a preferred embodiment, at least one parameter attributed to the appearance of the at least one visual stimulus may be varied between a first value and a second value, particularly in a continuous manner, more particularly in a monotonous manner. As used herein, the term "varied" refers to a change in the appearance or a look of the at least one stimulus caused by a time-variance of one parameter attributed to the at least one visual stimulus. As used herein, the term "continuously" means that the parameter attributed to the appearance is varied perpetual and/or ongoing. The term "monotonously" means that the parameter attributed to the appearance is varied uniformly and/or in a steady manner. In other word, the change in the parameter may be not time-varying but be maintained.

In a preferred embodiment, the at least one parameter may be selected from at least one of:.

As generally used, the term "contrast" refers to a luminance level in the at least one visual stimulus. As further generally used, the term "spatial frequency" refers to a reciprocal value of a spatial distance reflecting a spatial period of repetition in the at least one visual stimulus. As further generally used, the term "color" refers to a wavelength of a pattern as used in the at least one visual stimulus. As further generally used, the term "time-related frequency" refers to a repetition frequency of a periodic visual stimulus, particularly a number of repetitions of a periodic stimulus moving through a certain spatial point per unit time.

In a preferred embodiment, for the at least one parameter attributed to the appearance at least one of:.

As used herein, the term "threshold" refers to a minimum and/or maximum parameter setting that a stimulus must reach in order to trigger an excitation, a sensation or a reaction, particularly in order the elicit the at least on eye movement.

In a preferred embodiment, a plurality of at least one parameter may be attributed to the appearance, particularly wherein a plurality of at least one parameter attributed to the appearance is varied between a first value and a second value, particularly in a continuous manner, more particularly in a monotonous manner.

In a preferred embodiment, step c) may be performed during step a) and/or step b). In a preferred embodiment, displaying of the at least one visual fixation mark is stopped before step b). As used herein, the term "stopped" refers to a cessation of the displaying of the at least one visual fixation. The at least one visual fixation mark is disappearing. The at least one visual fixation mark is then no longer perceivable to the at least one eye of the person.

In a preferred embodiment, a gaze position of the at least one eye of the person may be checked during step a). As used herein, the term "gaze position" refers to a point of fixation in which the at least one line of sight and at least one object intersect. Particularly when the gaze position is known, it is possible that in a preferred embodiment, the center of the fixation mark may be displayed in a central field of view during step a). In a further preferred embodiment, the gaze position may be checked whether it is inside or outside an area of the at least one visual fixation mark during step a); particularly step b) may only be performed when the gaze position is inside the area of the at least one visual fixation mark.

In a preferred embodiment, the area of the at least one visual fixation mark may at least partially and/or completely be located within the central field of view. The term "area of the at least one visual fixation mark" may refer to the field on the screen on which the item, particularly the at least one visual fixation mark, is displayed. In a preferred embodiment, the at least one visual performance of the at least one eye may be determined outside the central field of view in a peripheral field of view. In a preferred embodiment, the center and/or the area of the at least one visual stimulus may be displayed in the peripheral field of view during step b).

In a preferred embodiment, displaying the at least one visual stimulus during step b) may be s stopped when the at least one eye movement has been tracked, in particular when the at least one eye movement has been elicited by the at least one visual stimulus. In a preferred embodiment, during step b) the at least one visual stimulus may be displayed for a maximum of a predetermined time. As used herein, the term "predetermined time" refers to a defined time value.

In a preferred embodiment, step b) may be repeated when at least one visual disturbance which affects the ability of the at least one eye of a person to observe the visual stimulus is detected. As used herein, the term "visual disturbance" refers to a reason and/or obstacle that hinders the at least one eye of the person to perceive the at least one visual stimulus and/or the at least one fixation mark. The visual impairment may particularly be at least indirectly and/or directly related to a condition of the at least one eye of the person. The visual impairment may be detectable by the at least one eye tracking device.

In a preferred embodiment, the at least one visual disturbance may be selected from at least one of:.

As generally used, the term "blink" refers to a rapid, usually involuntary and unnoticed closing and opening of an eyelid of the at least one eye of the person. As generally used, the term "vergence" refers to the simultaneous movement of both eyes of the person in opposite directions to obtain focus on a common gaze position. As generally used, the term "vergence angle" refers to an angle between the line of sights of both eyes that intersect in the gaze position.

In a preferred embodiment, during step b) the second spatial location of the at least one visual stimulus may be maintained. In other words, the second spatial location of the at least one visual stimulus may not vary over time. In a preferred embodiment, the second spatial location at which the at least one visual stimulus is displayed may be determined randomly by an algorithm. As used herein, the term "algorithm" refers to a set of instructions for solving a problem or a class of problems. The algorithm may, in particular, comprise instructions for a computer.

In a preferred embodiment, the second spatial location at which at least one subsequent visual stimulus in at least one subsequent measurement cycle is displayed, may be determined by considering at least one particular visual stimulus, particularly by considering an outcome of at least one particular visual stimulus determined in at least one particular measurement cycle. As used herein, the term "outcome" refers to recorded data used in the analysis of the at least one visual performance. The outcome may be recorded continuously during each measurement cycle in such a manner that data recorded during one measurement cycle is continuously added to the outcome. The outcome may thus comprise at least a portion of the data and/or all data recorded in at least a portion of the measurement cycles and/or in all measurement cycles.

In a preferred embodiment, the second spatial location at which at least one subsequent visual stimulus in at least one subsequent measurement cycle is displayed, may be determined by considering at least one particular visual stimulus by using a psychometric procedure. As generally used, the term "psychometric procedure" refers to a theory-based, standardized test for measuring psychological characteristics of a person. Such a test makes statements about how reliably the characteristic is determined, particularly how reliably the at least one visual performance within the visual field is determined, particularly the at least one visual performance at the at least one point in the visual field. To apply the psychometric procedure, the outcome may be analyzed at least one time during the measurement, particularly the at least one visual parameter may be determined.

In a preferred embodiment, the psychometric procedure may be selected from at least one of:.

As generally used, the term "staircase procedure" refers to a method in which a plurality of stimuli, particularly a modification of the at least on visual stimulus, are presented in ascending and/or descending order in subsequent measurement cycles. When the person's response changes, particularly when the at least one visual stimulus is no longer perceived and/or perceived for the first time, the direction of the stimulus sequence is reversed. As generally used, the term "Bayesian method" refers to a statistical inference procedure in which prior information about at least one population parameter with evidence from information contained in a sample is combined to guide a statistical inference process. Particularly in the context of psychophysical measurements, the term "Bayesian method" refers to a statistical inference procedure in which prior information about a psychometric function parameter space is combined with information from measurement samples, particularly from an outcome generated in a plurality of measurement cycles, to calculate at least one probability distribution of at least one psychometric function parameter and to guide the at least one visual stimulus accordingly, in particular to guide the visual stimulus by varying the at least one parameter and/or the spatial location of the at least one visual stimulus, accordingly.

In a preferred embodiment, the second spatial location of the at least one visual stimulus may be with regard to the fixation mark in at least one of:.

As generally used, the term "inferior visual field" refers to a portion of the visual field above a horizontal line through the line of sight. As generally used, the term "superior visual field" refers to a portion of the visual field below a horizontal line through the line of sight. As generally used, the term "nasal visual field" refers to a portion of the visual field lateral to a vertical line through the line of sight on the side where the nose is. As generally used, the term "temporal visual field" refers to a portion of the visual field lateral to a vertical line through the line of sight on the side where the temple is. In a preferred embodiment, from at least one outcome generated in four measurement cycles as well the top spatial location, the bottom spatial location, the left spatial location and the right spatial location of the at least one visual performance may be determined.

In a preferred embodiment, the fixation mark may be a particular item designated for directing the view, particularly the gaze position, of the at least one eye thereto, preferably wherein the at least one fixation mark may be selected from at least one of:.

In a preferred embodiment, in at least two measurement cycles and/or in all measurement cycles comprising step a) the at least one fixation mark may be displayed at the same first spatial location. In a preferred embodiment, a reaction time may be determined, particularly during step b) for determining the visual attention, wherein the reaction time is a time difference between displaying the at least one visual stimulus on the at least one screen and an occurrence of the at least one eye movement, in particular the occurrence of the at least one eye movement as elicited by the at least one visual stimulus. In a preferred embodiment, the reaction time may be a time difference between a beginning of the displaying of the at least one visual stimulus on the at least one screen and the beginning of the at least one eye movement, in particular the beginning of the at least one eye movement that has been elicited by the at least one visual stimulus.

In a preferred embodiment, a flag may categorize the at least one visual stimulus displayed during step b) as "seen", when the at least one eye movement has been tracked during displaying the at least one visual stimulus, in particular when the at least one eye movement has been elicited by the at least one visual stimulus. As generally used, the term "flag" refers to a status indicator that is may be used as a tool to indicate a certain states, particularly a status of the occurrence of the at least one eye movement. A flag may be set, deleted or checked. In a preferred embodiment, a flag may categorize the at least one visual stimulus displayed during step b) as "not seen", when the at least one eye movement has not been tracked during displaying the at least one visual stimulus, in particular when the at least one eye movement has not been elicited by the at least one visual stimulus.

In a preferred embodiment, step b) may comprise emitting an attention stimulus configured direct a focus of the person to an upcoming displaying of the at least one visual stimulus. As used herein, the term "emitting" refers to the issuing the attention stimulus perceivable by the person. As generally used, the term "focus" refers to the center of interest or activity of the person. It may refer to the ability of the person to concentrate on the next visual stimulus, wherein the next visual stimulus is not yet displayed at the point in time at which the attention stimulus is emitted but will be displayed after emitting the at least one visual stimulus.

In a preferred embodiment, the attention stimulus may be selected from at least one of:.

As used herein, the term "visual signal" refers to an attention stimulus that is displayed to the at least one eye of the person. The term "audio signal" is an attention stimulus that is perceptible by a sense of hearing of the person. The term "tactile signal" refers to an attention stimulus that is perceived by a haptic sensation, for example haptic sensations such as, but not limited to, tickling, a touch, a movement, a vibration, a temperature, a pressure and/or a tension.

In a preferred embodiment, determining the at least one visual performance may comprise analyzing the at least one outcome. In a preferred embodiment, at least one outcome may be generated which comprises for at least one circle at least one of:.

As used herein, the term "generating" or any grammatical deviation thereof refers to recording the measured data. The at least one outcome may comprise data recorded in a plurality of measurement cycles. As generally used, the term "analyzing" or any grammatical variation thereof refers to a systematic investigation in which the at least one outcome under investigation is broken down into its components. These components are thereby recorded on the basis of criteria and subsequently ordered, examined and evaluated.

In a preferred embodiment, at least one outcome may be generated that comprises for the at least one circle:.

In a preferred embodiment, a plurality of reaction times of the at least one particular measurement cycle and/or wherein a plurality of reaction times of the at least one subsequent measurement cycle may be correlated, in particular correlated by.

As used herein, the term "correlate" refers to a mutual interaction of information, which is implemented in such a manner that the interaction generates an output. The term "mean-value" refers to a scaled sum, particularly the sum of the values scaled by dividing by the number of values. The term "maximal value" refers to the largest value. The term "minimal value" refers to the smallest value.

In a preferred embodiment, the at least one subsequent measurement cycle may be performed later than the at least one particular measurement cycle by a time interval of at least <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM> or <NUM>. As generally used, the term "time interval" refers to a definite length of time marked off by two time stamps.

According to a further aspect, the present invention relates to a computer program comprising instructions which, when the program is executed by a computer, cause the computer to carry out at least one step, preferably all steps, of the computer-implemented method for determining at least one visual performance of at least one eye of a person as disclosed herein. For this purpose, a computer program may comprise instructions provided by means of a computer program code which are capable of performing any or all of the steps of the methods according to the present invention when implemented on a computer or a data processing device. The computer program code may be provided on a data storage medium or a separate device such as an optical storage medium, e.g. on a compact disc, directly on a computer or data processing device, or via a network, such as via an in-house network or via internet. For further details concerning the computer program, reference may be made to the methods according to the present invention as disclosed elsewhere herein.

According to a further aspect, the present invention relates to an apparatus for determining at least one visual performance of at least one eye of a person, the apparatus comprising:.

wherein the at least one processing device is configured for determining the at least one visual performance of the at least one eye of the person for at least one point in a visual field of the person by using a first spatial location of the at least one visual fixation mark and a second spatial location of the at least one visual stimulus; wherein an attention level of the person is determined by evaluating a time-related difference in the reaction times between the at least one particular measurement cycle and the at least one subsequent measurement cycle.

In a preferred embodiment, the apparatus further may comprise at least one of:.

As generally used, the term "connecting interface" refers to shared boundary across which two or more separate components of a computer system exchange information. The exchange can be between software, computer hardware, peripheral devices, humans, and combinations of these.

In a preferred embodiment, the connecting interface may be selected from at least one of:.

As generally used, the term "network interface controller" refers to a computer hardware component that connects a computer to a computer network. As generally used, the term "transmitter" refers to an electronic device, which produces electromagnetic waves with an antenna.

In a preferred embodiment, the apparatus may be selected from at least one of:.

As used herein, the term "stand-alone computer" refers to a computer that is not necessarily connected to any other computer. Users can interact with the stand-alone computer, enter and process data, but no data or information is exchanged with other computers in the process of determining the visual performance within a visual field of at least one eye of a person. As generally used, the term "personal computer" refers to a multifunctional computer with a geometry and capabilities making it useful in everyday situations. As generally used, the term "virtual reality headset" refers to a head-mounted device that provides virtual reality for the wearer. As generally used, the term "augmented reality overlay device" refers to a hardware for an interactive experience between a real-world environment and computer-generated perceptual information. As generally used, the term "television set" refers to a device having a tuner, a display and at least one loudspeaker for a purpose of viewing and listening to television broadcasting through at least one of satellite or cable, wherein the television set may also be used as a monitor. As generally used, the term "mobile communication device" refers to a portable wireless telecommunications equipment that may transmit and/or receive voice, video, or computer data.

In a preferred embodiment, the mobile communication device may be selected from at least one of:.

As generally used, the term "smartphone" refers to a mobile phone having extensive computer functionalities and connectivity. As generally used, the term "tablet" refers to a portable, flat touch-screen computer. As generally used, the term "laptop" refers to a special type of computer having a screen movably attached to a housing, wherein the screen may be folded onto the housing.

In a preferred embodiment, the at least one screen may be selected from at least one of:.

As generally used, the term "monitor" refers to an electrically controlled display for a visual displaying of information such as an image or an item. As generally used, the term "touchscreen" refers to device having a screen that can be touch to generate an input. As generally used, the term "projector" refers to an optical device for enlarging a two-dimensional original by suitable guidance of light rays.

In a preferred embodiment, the at least one eye-tracking device may be selected from at least one of:.

As generally used, the term "camera" refers to an optical device that captures visual images. As generally used, the term "webcam" refers to a small camera that may sit on a monitor, or is built into a computer. As generally used, the term "eye tracking glasses" refers to a spectacle having an attached sensor for tracking an eye. As generally used, the term "visually evoked potential device" refers to a device configured for recording of a specific part of the nervous system.

In a preferred embodiment, the apparatus may be configured for carrying out at least one step, preferably all steps, of the computer-implemented method for determining at least one visual performance within a visual field of at least one eye of a person.

A remote apparatus for determining at least one visual performance of at least one eye of a person, not part of the invention, is also disclosed, the remote apparatus is comprising:.

As generally used, the term "receiving" refers taking and beginning to process the at least one outcome provided by computer-implemented method for determining the at least one visual performance within the visual field of the at least one eye of a person.

With respect to the prior art, the device exhibits the following advantages.

Visual performance tests for determining a visual performance for a specific point in a visual field as known from the state of art mostly require an ophthalmologist or optometry specialist. Therefore, such test result in reduced portability and cannot be performed by a person itself. The automated test of the present invention on the other hand may be performed by the person itself, particularly by using a mobile device.

As the eye movement is measured directly using an eye tracking device, the test has the advantage that it does not require any further response of the patient. This makes testing of children or patients with disabilities easier.

The visual performance may be determined for the peripheral field of view as the determination is carried out in a spatially resolved manner in such a way that the visual performance is assigned to a point in the visual field.

The testing is time efficient, as a one-trial-only testing procedure may be performed, particularly in combination with a smooth enhancement of the visual stimulus, and particularly by considering the first threshold and the second threshold as well as psychometric procedures. It is further possible to monitor a time dependency of the visual field.

As used herein, the terms "have", "comprise" or "include" or any arbitrary grammatical variation thereof are used in a non-exclusive way. Thus, these terms may refer to both a situation in which, besides the feature introduced by these terms, no further features are present in the entity described in this context and to a situation in which one or more further features are present.

As further used herein, the terms "preferably", "more preferably", "particularly", "more particularly", or similar terms are used in conjunction with optional features, without restricting alternative possibilities. Similarly, features introduced by "in an embodiment of the invention" or similar expressions are intended to be optional features, without any restriction regarding alternative embodiments of the invention, without any restrictions regarding the scope of the invention and without any restriction regarding the possibility of combining the features introduced in this way with other features of the invention.

Further optional features and embodiments of the present invention are disclosed in more detail in the subsequent description of preferred embodiments, preferably in conjunction with the dependent claims. It is emphasized here that the scope of the invention is not restricted by the preferred embodiments.

<FIG> shows an exemplary apparatus <NUM> for determining a visual performance within a visual field <NUM>, <NUM> of an eye <NUM> of a person <NUM>. The apparatus <NUM> according to <FIG> is a mobile communication device, especially a smartphone. Alternatively, the apparatus <NUM> may be a system comprising a stand-alone computer, a monitor, and a camera; a system comprising a personal computer, a monitor, and a camera; a virtual reality headset; an augmented reality overlay device; a television set; a tablet; or a laptop.

The visual performance which is exemplarily determined here is a visual acuity in the peripheral field of view <NUM>. Alternatively or in addition, a contrast sensitivity, a color vision, a time-related sensitivity and/or a visual attention may be determined.

The apparatus <NUM> comprises a screen <NUM> according to <FIG>. On the screen <NUM> a visual fixation mark <NUM> is displayed to the eye <NUM> of the person <NUM>. To determine the visual performance, a visual stimulus <NUM> is, subsequently, displayed on the screen <NUM> in order to elicit an eye movement in the eye <NUM> of the person <NUM> (not depicted here). The screen <NUM> as depicted in <FIG> is a touchscreen of the smartphone. Alternatively, the screen <NUM> may be a monitor, a virtual reality head set, a television set, or a projector.

The apparatus <NUM> comprises an eye-tracking device <NUM> configured for tracking the eye movement in the eye <NUM> of the person <NUM>. The eye-tracking device <NUM> according to <FIG> is a camera integrated into the smartphone. Alternatively, the eye-tracking device <NUM> may be a webcam, an eye tracking glasses, or a visually evoked potential device. The eye-tracking device <NUM> according to <FIG> is further used as a distance measuring unit. For this purpose, it is configured for measuring and recording a distance between the eye <NUM> of the person <NUM> and the visual stimulus <NUM>. Further, the distance between the visual fixation mark <NUM> the eye <NUM> of the person <NUM> can be measured and recorded.

To determine the visual performance within the visual field <NUM>, <NUM> of the eye <NUM> of the person <NUM>, a computer-implemented method <NUM> may be applied. The method <NUM> may be implemented as a computer program that is running on the apparatus <NUM>.

According to <FIG>, in a first displaying step <NUM> according to step a) of the method <NUM> the visual fixation mark <NUM> is displayed on the screen <NUM> to the eye <NUM> of the person <NUM>. The fixation mark <NUM> as depicted here is an artificial pattern, specifically a fixation cross. Alternatively, the fixation mark <NUM> may be a specific natural image, a specific virtual image, a circle, particularly a blank circle, a dot, or a cartoon. The fixation mark <NUM> is displayed in a center area <NUM> of the screen <NUM>. The spatial location of the visual fixation mark <NUM> is maintained in a constant manner during at least one measurement cycle <NUM>, preferably a plurality of measurement cycles <NUM>. A first spatial location of the visual fixation mark <NUM> is recorded.

The fixation mark <NUM> is designated for directing the view, particularly a gaze position, of the eye <NUM> thereto. In <FIG>, the gaze position is in an area defined by the visual fixation mark <NUM> and therefore a line of sight <NUM> of the eye <NUM> intersects with the visual fixation mark <NUM>. The eye <NUM> is in a neutral position. As a result, the center <NUM> of the visual fixation mark <NUM> is displayed in a central field of view <NUM> of the eye <NUM> of the person <NUM> during the first displaying step <NUM>. The area of the visual fixation mark <NUM> is completely located within the central field of view <NUM>. The center area <NUM> of the screen <NUM> corresponds to the central field of view <NUM>.

The central field of view <NUM> is defined by a central field of view angle β between a third connecting line <NUM>, connecting an outer perimeter <NUM> of the central field of view <NUM> and the line of sight <NUM> of the eye <NUM> of the person <NUM> that goes through the reference position in eye <NUM> of the person <NUM>. The outer perimeter <NUM> may be a maximal circumference of the central field of view <NUM>. The central field of view angle β as depicted in <FIG> is <NUM>°. Alternatively, the central field of view angle β may be <NUM>°, <NUM>°; <NUM>°; <NUM> °; <NUM>° or <NUM>°. The reference position in the eye <NUM> may be a pupil center, a corneal reflex, or a corneal apex.

The eye-tracking device <NUM> is further used to check if a gaze position of the eye <NUM> is whether inside or outside an area comprising a second spatial location of a center <NUM> of the visual fixation mark <NUM> during the first displaying step <NUM>. When the gaze position is inside the area of the visual fixation mark <NUM> a second displaying step <NUM> according to step b) of the method <NUM> may be performed.

According to a second displaying step <NUM> of the method <NUM>, the visual stimulus <NUM> is displayed on the screen <NUM> to elicit an eye movement in the eye <NUM> of the person <NUM> as depicted in <FIG>. The expected eye movement is a reflexive saccade. As can be seen in the <FIG>, displaying of the visual fixation mark <NUM> is stopped before the second displaying step <NUM> and therefore the visual fixation mark <NUM> is indicated in these Figures by dashed lines. Alternatively, the visual fixation mark <NUM> may be displayed during the second displaying step <NUM>.

The visual stimulus <NUM> depicted in <FIG> is an artificial pattern, specifically a grating being a Gabor patch. Alternatively, the visual stimulus <NUM> may be a specific natural image, a specific virtual image, or a noise patch having at least one defined spatial frequency. The appearance of the visual fixation mark <NUM> and the appearance of the at least one visual stimulus <NUM> is different from each other.

The visual stimulus <NUM> may be displayed outside of the central field of view <NUM> in the peripheral field of view <NUM>. The second spatial location of the visual stimulus <NUM> may be located in a surrounding area <NUM> that completely encloses the center area <NUM>. This can be achieved by considering an angle α, which is defined between a first connecting line <NUM> and a second connecting line <NUM>. The first connecting line <NUM> connects the center <NUM> of the visual fixation mark <NUM> and a reference position in the eye <NUM> of the person <NUM>. The second connecting line <NUM> connects the center <NUM> of the visual stimulus <NUM> and the reference position in the eye <NUM> of the person <NUM>. As the visual stimulus <NUM> is displayed in the peripheral field of view <NUM>, the angle α is, according to <FIG>, larger than <NUM>°. Alternatively, it may be larger than <NUM>°, <NUM>°, <NUM>°, <NUM> °, <NUM>° or <NUM>°.

As can be seen in <FIG> that also illustrates the second displaying step <NUM>, the gaze position of the eye <NUM> of the person <NUM> changed onto the visual stimulus <NUM> as intended as the person <NUM> reacted to the displaying of the visual stimulus <NUM>. Consequently, the line of sight <NUM> also changed in a manner that it now intersects with visual stimulus <NUM>.

The at least one visual stimulus <NUM> is continuously displayed during the second displaying step <NUM> and the second spatial location of the visual stimulus <NUM> may be fixed. The second spatial location of the visual stimulus <NUM> may be defined by a certain eccentricity level and a certain spatial orientation of the center <NUM> of the visual stimulus <NUM> with regard to the center <NUM> of the visual fixation mark <NUM>.

During the displaying on the screen <NUM>, the appearance of the visual stimulus <NUM> is time-varying. For this, a parameter attributed to the appearance of the visual stimulus <NUM> is varied between a first value and a second value. The parameter may be varied in a continuous manner or even a monotonous manner. The parameter varied to determine the visual acuity is here a spatial frequency of the visual stimulus <NUM>, as can be seen by a comparison of <FIG>. Alternatively, the parameter may be a contrast, in particular for determining the contrast sensitivity; a color, in particular for determining the color vision; or a time-related frequency, in particular for determining a time-related sensitivity. It is further possible, that a plurality of parameters attributed to the appearance is varied between a first value and a second value. Also, the varying of the plurality of parameters may be in a continuous manner or in a monotonous manner.

According to a generating step <NUM> according to step c) of the method <NUM> for determining the visual performance within the visual field <NUM>, <NUM> of the eye <NUM> of the person <NUM>, the eye movement is tracked using the eye-tracking device <NUM>. Therefore, a time variance of the gaze position or a time variance of the line of sight <NUM> may be recorded.

For the parameter attributed to the appearance a first threshold may be determined at which the eye movement in the eye <NUM> of the person <NUM> is tracked for the first time and a second threshold value may be determined at which the eye movement in the eye <NUM> of the person <NUM> is tracked for the last time.

Additionally, also a pupil size of a pupil <NUM> of the eye <NUM> of the person <NUM> is recorded by using the eye tracking device <NUM>. By doing so, a time-variance of the pupil size may be recorded.

<FIG> gives an overview of the sequence of the steps according to the method <NUM> for determining the visual performance of the eye <NUM> of the person <NUM>. A generating step <NUM> according to step c) is performed during the first displaying step <NUM> according to step a) and the second displaying step <NUM> according to b). Herein, the first displaying step <NUM> is performed before the second displaying step <NUM>. A measurement cycle <NUM> may comprise a sequence of the first displaying step <NUM>, the second displaying step <NUM> and the generating step <NUM>; however, the first displaying step <NUM> may not, necessarily, be comprised by the measurement cycle <NUM>. To determine the visual performance for further points in the visual field <NUM>, <NUM> the visual stimulus <NUM> is displayed at different second spatial locations during the second displaying step <NUM> during a plurality of measurement cycles <NUM>. The method <NUM> for determining the visual performance within the visual field <NUM>, <NUM> further comprises a determining step <NUM> according to step d) of the method <NUM>.

During the second displaying step <NUM> the visual stimulus <NUM> may be displayed for a maximum of a predetermined time. In case the eye movement may not be elicited within the predetermined time, the second displaying step <NUM> may then be repeated using a visual stimulus <NUM> having a different parameter and/or spatial location.

Displaying the at least one visual stimulus <NUM> during the second displaying step <NUM> may be stopped, when the at least one eye movement elicited by the visual stimulus <NUM> has been tracked. In this case, the second displaying step <NUM> may then be considered as being completed.

The second displaying step <NUM> may, further, be repeated when a visual disturbance may be detected, which affects the ability of the eye <NUM> of the person <NUM> to observe the visual stimulus <NUM>. Such a disturbance may be a blink of the eye <NUM> of the person <NUM>, a gaze position of the eye <NUM> outside of the screen <NUM> displaying the visual stimulus <NUM>, a vergence angle between both eyes of the person <NUM> showing that the person <NUM> is not focusing on the screen <NUM>, or a pupil size showing that the person <NUM> is not focusing on the screen <NUM>.

According to <FIG>, <FIG>, the second spatial location of the visual stimulus <NUM> is with regard to the fixation mark <NUM> at a top spatial location for determining the visual performance of an inferior visual field. Alternatively, it may be at a bottom spatial location for determining the visual performance of a superior visual field, a left spatial location for determining the visual performance of a nasal visual or a temporal visual field, respectively, or a right spatial location for determining the visual performance of the temporal visual field or the nasal visual field, respectively. To determine the peripheral field of view <NUM> in the inferior visual field, the superior visual, the nasal visual and the temporal visual field an outcome may be generated from four measurement cycles <NUM> in which the visual stimulus <NUM> is displayed at the top spatial location, the bottom spatial location, the left spatial location and the right spatial location. On the other hand, the visual fixation mark <NUM> may be displayed at the same spatial location during the first displaying step <NUM> of each measurement cycle <NUM>.

The second spatial location at which the visual stimulus <NUM> may be displayed is determined randomly by an algorithm. Alternatively or in addition, the second spatial location at which a subsequent visual stimulus <NUM> in a subsequent measurement cycle <NUM> is displayed may be determined by considering an outcome of a particular visual stimulus <NUM> determined in a particular measurement cycle <NUM> as performed before the subsequent measurement cycle <NUM>. For doing so, a psychometric procedure may be used that may be selected from a staircase procedure or a Bayesian method.

To determine the visual attention a reaction time may be recorded. The reaction time may be a time difference between displaying the visual stimulus <NUM> on the screen <NUM> and an occurrence of the at least one eye movement elicited by the visual stimulus <NUM>. This measurement may, further, include emitting an attention stimulus configured to direct a focus of the person <NUM> to an upcoming displaying of the visual stimulus <NUM>. The attention stimulus may be a visual signal, an audio signal, and/or a tactile signal.

After each measurement cycle <NUM> an outcome may be generated including the tracking data generated by the eye tracking device <NUM> and the second spatial location at which the visual stimulus <NUM> is displayed on the screen <NUM>. Additionally, the outcome may include the visual stimulus <NUM>, the tracking data generated by the eye tracking device <NUM>, a flag, the first threshold, the second threshold, the pupil size, the reaction time, and/or the attention stimulus.

The flag can be used to categorize the visual stimulus <NUM> displayed during step b) as "seen", when the eye movement elicited by the visual stimulus <NUM> has been tracked during displaying the visual stimulus <NUM>. The flag can, further, be used to categorize the visual stimulus <NUM> displayed during step b) as "not seen", when the eye movement elicited by the visual stimulus <NUM> has not been tracked during displaying the visual stimulus <NUM>.

The outcome can be analyzed to determine the visual performance by using at least one processing device of the apparatus <NUM> for the points in the visual field <NUM>, <NUM> that correspond to the second spatial locations at which the visual stimulus <NUM> has been displayed. To determine the at least one visual performance of a specific point in the visual field during the determining step <NUM> an assignment rule can be applied. The assignment rule may consider the first spatial location of the visual fixation mark <NUM> and the second spatial location of the visual stimulus <NUM>. The assignment rule may, further, consider a distance between the eye <NUM> of the person <NUM> and the visual stimulus <NUM> and/or the visual fixation mark <NUM>.

Additionally, an attention level of the person <NUM> is determined by evaluating a time-related difference in the reaction times between the particular measurement cycle <NUM> and the measurement cycle <NUM> that was performed a given time interval later than the particular measurement cycle <NUM>. In this analysis, a plurality of reaction times of the particular measurement cycle <NUM> and a plurality of reaction times of the subsequent measurement cycle <NUM> may be correlated, for example by calculating a mean-value, determining a maximal value, or determining a minimal value.

Claim 1:
A computer-implemented method (<NUM>) for determining at least one visual performance of at least one eye (<NUM>) of a person (<NUM>), wherein the method comprises at least the following steps:
a) displaying on a screen (<NUM>) to the at least one eye (<NUM>) of a person (<NUM>) at least one visual fixation mark (<NUM>) configured to attract a visual perception of the person (<NUM>) by directing a line of sight (<NUM>) of the at least one eye (<NUM>) of the person (<NUM>) towards the visual fixation mark (<NUM>);
b) subsequently displaying on a screen (<NUM>) to the at least one eye (<NUM>) of the person at least one visual stimulus (<NUM>) configured to elicit at least one eye (<NUM>) movement in the at least one eye (<NUM>) of the person (<NUM>) towards the at least one visual stimulus (<NUM>);
c) generating tracking data about the at least one eye movement of the at least one eye (<NUM>) of the person (<NUM>) by using at least one eye-tracking device (<NUM>); and
d) determining the at least one visual performance from the tracking data by using at least one processing device;
wherein the at least one visual performance of the at least one eye (<NUM>) of the person (<NUM>) is determined for at least one point in a visual field of the person (<NUM>) by using a first spatial location of the at least one visual fixation mark (<NUM>) and a second spatial location of the at least one visual stimulus (<NUM>);
characterized in that
an attention level of the person (<NUM>) is determined by evaluating a time-related difference in reaction times between at least one particular measurement cycle (<NUM>) and at least one subsequent measurement cycle (<NUM>).