GB2566275A

GB2566275A - Measuring variations in perception

Info

Publication number: GB2566275A
Application number: GB1714338.9A
Authority: GB
Inventors: Henry Joel Burleigh Alistair; Christian Pepperell Robert; Ruta Nicole
Original assignee: Fovo Technology Ltd
Current assignee: Fovo Technology Ltd
Priority date: 2017-09-06
Filing date: 2017-09-06
Publication date: 2019-03-13
Also published as: GB201714338D0

Abstract

An apparatus, system and method for measuring space perception in the human visual field, the system comprising: a rotatable support structure encompassing the full field of view of the subject; a reference object R with modifiable properties; one or more stimuli S with modifiable properties located on the support structure. There is also a subject response collection device and a control unit configured to control the support structure and the modifiable properties of the reference object and stimuli, receive the subject response, analyse the responses to determine a subject's space perception. The stimuli may be lights, colour changing material or video displays. The stimuli may be moveable closer to the subject, who may be seated in a chair with an adjustable chin rest. The method includes stimulating the peripheral visual field of the subject, recording the responses and analysing the set of data to give a measurement of their space perception, this may include a mathematical analysis.

Description

MEASURING VARIATIONS IN PERCEPTION

The present invention is directed to measuring and mapping variations in the perception of space and depth in humans across the full binocular visual field. Specifically the disclosed invention permits a clinician or scientific researcher to present a patient or experimental participant with stimuli that can be adjusted, either by the operator or the participant, such that the perceived appearance of an object seen in the visual periphery can be compared to a reference object seen in the centre of the visual field. Variations between the perceived appearance of stimuli and their actual known appearance can be used to calculate how the person perceives visual space.

Physical space is generally regarded as Euclidean in nature, and can be measured using standard Cartesian coordinates. Human perception of visual space, however, is widely regarded as non-Euclidean. This means that we do not perceive space as uniformly distributed, even though everyday experience might lead us to assume that we do. For example, we tend to overestimate distances that are physically close to us and underestimate distances that are far away. So the size of a distant mountain is likely to appear smaller than it is, while a very close object is likely to appear bigger.

The matter becomes more complicated when we consider the structure of the human visual field, which in normal vision consists of two fields, one for each eye, covering a scope of some 1802 horizontally and some 1302 vertically in a roughly oval shape. The foveated area of this visual field is relatively small, some 22 at the centre, yet is served by the highest population of light sensitive cells in the retina, and this is where we see with the greatest acuity. The remainder of the visual field is seen with less acuity, being detected by regions of the retina less densely populated with light sensitive cells. One consequence of this physiological structure of the visual system is that the size and shape of objects seen in the foveated region of the visual field will appear different when seen in the periphery. However, human perception is an active process that selects and interprets visual information coming from the retina. In normal visual behaviour we move our eyes and heads constantly, and through this we accumulate psychological representations of objects around us compounded from many foveated views. Hence, we remain largely unaware of the variations of size and shape in perception of objects across the entire visual field as we are rarely called on to attend closely to the phenomenal appearance of peripheral vision.

Measuring these variations in perceived size and shape of objects across the full visual field is technically challenging. Experiments have been conducted which have focused on the regions around the fovea, up to 202 _Or so of the visual field, but few have been conducted on greater eccentricities, and hardly any on the far peripheral field. One reason is the need to encompass the entire visual field in a way that allows for accurate and reliable presentation of stimuli without overly discomforting the person being tested. The use of flat monitors or flat projections, which is currently the norm in vision science, restricts the coverage of the visual field, and using multiple or chained screens creates problems with respect to time synchrony and calibration.

Projecting on curved or dome screens is technically possible using video, laser, or data projectors. However current projectors are limited in display resolution, the optics needed to map to the curved screen can be expensive and time consuming to align, and in the case of smaller hemispherical projection environments very difficult to position without physically blocking visibility and access to a large proportion of the dome. There can also be complex limitations with display refresh rates and the consistency and reliability of factors like luminance, contrast, and gamma correction across multi angled projection surfaces. Furthermore, it is necessary in order to obtain accurate judgements of perceived space that the stimuli alone are visible to the patient or participant, and that the structure of the device to which the stimuli are attached remain invisible. This is because the visibility of the structure can affect the perceived distance or size of the stimuli. Many projectors and most monitors do not produce a true black, and emit light whether or not an image is being projected or displayed, meaning they can contaminate the device with unwanted light and so reveal aspects of the structure it is necessary to conceal.

It is well established that space perception varies significantly between individuals, and can vary as a function of developmental factors and medical disorders. Thus, children, neurodiverse individuals, or physiologically impaired patients can experience space differently from developed, neuro-typical, or healthy individuals. This can have important implications for health and safety, for diagnosis of medical conditions, for tracking development or degeneration and recovery from medical conditions. Current devices designed to measure visual space perception do not accommodate the entire binocular field of view, nor are they able to measure depth perception at arbitrary distances from the patient or participant being tested. There is a need for devices and methods that reliably map the structure of visual space and measures human perception across the full binocular visual field extending beyond the field of vision science research.

In a first aspect, the present invention discloses an apparatus for measuring space perception in the human visual field of a subject comprising:

a rotatable support structure (D), encompassing the full field of view of the subject;

a reference object (R), wherein the reference object has modifiable properties; and, one or more stimuli (S), located on the support structure, wherein the one or more stimuli have modifiable properties.

In an embodiment, the apparatus may further comprise an adjustable chair (C) for the subject and an adjustable chin rest (A) for the subject.

In an embodiment, the apparatus may further comprise a light proof box (B) with a viewing aperture masking the features of the apparatus from the subject until they are seated correctly and preventing external light entering the apparatus. The light proof box may have a removable blanking window for placing over the aperture when measurements are not being taken.

In an embodiment, the apparatus may further comprise a lightproof box (L) which encompasses the apparatus.

In an embodiment, the support structure (D), may be a hemispherical support bar. The support structure may be geometrically an 180° to 200° arc.

In an embodiment, the apparatus may further comprise a stand (F), wherein the centre of support bar (D) is attached to the stand.

In an embodiment the support bar (D) may be presented in a concave orientation to the subject. The support bar (D) may be in a horizontal position in its default state.

In an embodiment the support bar (D) may be rotatable around its attachment point 45^ clockwise or 45^ anticlockwise. The support bar (D) may be rotated using a lever (E) to rotate in 1° increments. The lever (E) may be provided with a locking means.

In an embodiment the support bar (D) may be constructed of metal, wood, plastic, or a compound of materials. The support bar (D) may be of any height, width or depth dimensions.

In an embodiment the reference object (R) may be positioned inline with the height centre of the subject's (P) pupils.

In an embodiment the reference object (R): may be a light source; may be provided with masks to produce illuminated shapes; may be provided with an illuminated image; may be provided with colour changing material; the luminance of the reference object (R) may be controlled; the timing of the illumination of reference object (R) may be controlled;

In an embodiment the reference object may have an adjustable aperture placed in between the object and subject to control its visible size. The adjustable aperture may have a range of substantially 1mm to 20mm.

In an embodiment the reference object (R) may comprise a video display device.

In an embodiment the reference object (R) may be attached to stand (F) via a tube integrated into the stand.

In an embodiment the reference object (R) may be moved towards and away from the subject (P). A lever (J) may be used to move the reference object (R).

In an embodiment electrical power and image signal may be passed to the reference object (R) from a control unit (H) via wiring (G).

In an embodiment the stimuli (S) may be identical in construction to reference object (R).

In an embodiment the stimuli (S): may be a light source; may be provided with masks to produce illuminated shapes; may be provided with an illuminated image; may be provided with colour changing material; may be transparent or semi-transparent; the luminance of the stimuli (S) may be controlled; the timing of the illumination of stimuli (S) may be controlled.

In an embodiment the stimuli (S) may have an adjustable aperture placed in between the stimuli (S) and subject to control its visible size. The adjustable aperture may have a range of substantially 1mm to 20mm.

In an embodiment the stimuli (S) may comprise a video display device.

In an embodiment the stimuli (S) may be attached is attached to a tube (M), wherein the tube (M) extends through an aperture in the support structure (D).

In an embodiment the stimuli (S) may be moved towards and away from the subject (P).

In an embodiment electrical power and image signal may be passed to the stimuli (S) from a control unit (H) via wiring (K).

In an embodiment the stimuli (S) may be moved around the support bar (D).

In an embodiment the stimuli (S) may have a locking system to fix its position on the support bar.

In an embodiment, the apparatus may further comprising a control unit (H) to operate the apparatus.

In an embodiment the one or more stimuli (S) may be placed in different positions.

In an embodiment the support structure (D) may comprise two arcs. The two arcs may be positioned one extending upward to 100° from the central axis and the other at 70°.

In an embodiment all components lying within the visual field of the subject and not intended to be visible may be coated in light absorbing material.

In a second aspect, the present invention discloses a system of measuring space perception in the human visual field of a subject comprising:

a rotatable support structure encompassing the full field of view of the subject;

a reference object, wherein the reference object has modifiable properties;

one or more stimuli, located on the support structure, wherein the one or more stimuli have modifiable properties;

a subject response collection means; and, a control unit, configured to control the support structure and the modifiable properties of the reference object and one or more stimuli, receive the subject response, analyse the responses to determine the space perception of a subject.

In an embodiment, the system may further comprise an adjustable chair and adjustable chin rest.

In an embodiment, the system may further comprise a light proof screen with a viewing aperture masking the features of the system from the subject until they are seated correctly and minimizing external light entering the system and a removable blanking window for placing over the aperture when measurements are not being taken.

In an embodiment the rotatable support structure may comprise one or more hemispherical support bars.

In an embodiment, the system may further comprise a stand, wherein the centre of the support structure is attached to the stand.

In an embodiment the support structure may be rotatable around its attachment point 45^ clockwise or 45^ anticlockwise.

In an embodiment the support structure may have an automatic rotating means to rotate in 1° increments.

In an embodiment the modifiable properties of the reference object may be, one ore more of: size, shape, illumination, colour, relative position to the subject.

In an embodiment the modifiable properties of the stimuli may be, one ore more of: size, shape, illumination, transparency, colour, relative position to the subject.

In an embodiment the relative position of the stimuli to the subject may be controlled by a mechanical movement means.

In an embodiment, the system may further comprise a calibration tool, to detect the features of the system and set the systems modifiable properties.

In an embodiment the subject response collection means may comprise, a device with buttons or slider sending the response signal to the control unit.

In an embodiment the subject response collection means may comprise, an eye tracking device to automatically collect response.

In an embodiment the rotatable support structure may be a hemispherical dome.

In an embodiment the stimuli may be permanently affixed to the dome.

In a third aspect, the present invention discloses a method of measuring space perception in the human visual field of a subject comprising the sequence of steps:

(1) aligning a subject with a space perception measurement apparatus or system as claimed in a any previous claim;

(2) selecting a region of a subject's vision to test;

(3) the subject fixates on a reference object;

(4) stimulating the subjects peripheral visual field with stimuli;

(5) gathering the subjects response to the stimuli;

(6) recording the responses;

(7) generating a set of data according to the subjects response;

(8) analysing the set of data to give a measurement of the subject's space perception.

In an embodiment the steps (2) to (6) may be repeated to cover multiple regions of a subjects vision.

In an embodiment step (1) of aligning the subject may be performed automatically.

In an embodiment the selection of step (2) may include determining a range of properties for the stimuli and the rotation of the measurement apparatus in response to the selected region.

In an embodiment the step (3) the fixation may be detected by use of an eye tracker.

In an embodiment during step (3) properties of the reference object may be modified.

In an embodiment the step (4) stimulation may be controlled based in the determined range of properties of the stimuli and rotation apparatus.

In an embodiment in step (5) the response of the subject may be a discrete or a variable measurement.

In an embodiment in step (6) the response may be recorded automatically or manually from the subject.

In an embodiment in step (7) the set of data may be generated and stored in a computer system.

In an embodiment step (8) may comprise mathematical analysis of the set of data, either manually or computationally, to provide a profile of the subjects individual judgements of visual space perception.

The invention may be performed in various ways and embodiments thereof will now be described, by way of example only, reference being made to the accompanying drawings, in which:

Figure 1 is a side elevation diagram showing the main components and operational functions of an embodiment of a first aspect of the present invention;

Figure 2 is a side elevation diagram showing the main components and operational functions of an embodiment of a second aspect of the present invention;

Figure 3 is a side elevation diagram showing the main components and operational functions of a further embodiment of a second aspect of the present invention;

Figure 4 is a diagram of one embodiment of the present invention, showing an example layout of the stimuli in the hemispherical dome; and,

Figure 5 is a flow chart illustrating the main steps in the present method, and the supplementary steps in the present method.

Figure 1 is a side elevation diagram showing a device 10 comprised of the main components and operational functions of one manually operated embodiment of the first aspect of the present invention. In this embodiment a person P, who is a patient or experimental participant, is seated in a chair C that is adjustable for height via a suitable mechanism, as indicated by the bidirectional arrow and equipped with an optional headrest or head restraint that acts to maintain the position and stability of the person's head. The height of the chair is adjusted such that the height of the centre of either of the person's pupils is perpendicular to the centre of the device occupied by the reference object R, shown as line X. A further chin rest A may be provided which is also adjustable, that stabilises the person's head at the correct position with respect to the device, as indicated by the bidirectional arrow. A light proof screen B fitted with a viewing aperture masks the internal components of the device from the person P until they are seated correctly, and also prevents external light entering the stimulus area of the device. An optional blanking window is fitted over the aperture that is opened only while measurements are being taken. Optionally, the entire device is housed in lightproof box L fabricated from a suitable material.

The main element of the device consists in a hemispherical support bar D, which geometrically is a 180^, 190^ or 200^ arc or spherical wedge, affixed at its centre point to a rigid stand F. Hemispherical support bar D is presented in concave orientation to the person P and in its default state is oriented horizontally. The support bar D is attached to the rigid stand F in such a way that the support bar can be rotated around its affixation point to the extent of 45^ clockwise or 45^ anticlockwise in increments of I² using the lever E provided, as indicated by the curved bidirectional dashed line arrow. Note that as support bar D rotates it moves freely with respect to light proof screen B. A locking mechanism is provided at the lever E that allows an operator of the device to rotate the support bar D to any desired degree, and stabilise the support bar such that it does not move until the locking mechanism is released. The support bar D may be fabricated from any suitable material, such as metal, wood, plastic, or a compound of materials. The support bar D may be of any dimensions, the chosen dimensions being determined by practical considerations such as the desired depth and breadth of measurements required, or the available laboratory or clinical examination space.

Located at the centre of the support bar D facing person P is a reference object R, the height centre of which is positioned in line with the height centre of the person's pupil. Reference object R is an illuminated object that can be adjusted in size, shape and position relative to the person P, as indicated by the bidirectional arrows.

The reference object R may be a unit constructed using a sheet of electroluminescent material or an arrangement of LED bulbs or other light source in front of which is attached a slot into which light proof masks can be mounted in order to create any desired illuminated shape. In addition, images printed onto transparent or translucent material may be mounted in order to create an illuminated image visible to the person P. In addition, coloured gels may be mounted to alter the colour of the reference object R visible to the person. The luminance of the reference object R can be controlled by a suitable circuit or resistors attached to the power supply of the light emitting object. The timing of the illumination of the reference object R can be controlled by a manually operated circuit breaking switch, or other suitable control mechanism, such that the operator can turn the illumination on and off at will.

The size of the visible area of the reference object R can be modified using an adjustable diaphragm or aperture placed in front of the illuminated material, the settings of which are controlled by the operator using a suitable mechanical or electrical device. In one embodiment of this arrangement, the size of the adjustable diaphragm varies from 1mm to 20mm, creating an illuminated disc of this varying size.

The size of the visible area of the reference object R can be modified using an illuminated inflatable bladder, the settings of which are controlled by the operator using a suitable mechanical or electrical device. In one embodiment of this arrangement, the size of the inflatable bladder varies from 1mm to 20mm, creating the appearance of an illuminated disc of this varying size to the person P.

The reference object R may be a unit constructed using a video display device, such as a microprojector, LCD, OLED or LED screen, or similar device, on which images can be displayed from a suitable source, such as a computer. This unit is fitted with a slot into which the items noted above are mounted. The operator controls the luminance and exposure time of the light emitted from the reference object R by adjusting the image source signal. In one embodiment, the screen is located behind an adjustable diaphragm or aperture, and the size of the adjustable diaphragm varies from 1 mm to 20 mm, creating an illuminated display image of this varying size.

The reference object R is attached to frame F, via bar D, by means of a tube integrated into the frame F and holding the reference object R in position. The reference object R can be moved towards and away from the person P using the lever J supported by the tube in increments of 1 mm, as indicated by the bidirectional arrow. The electrical power for the reference object R, and where relevant the image signal, is passed from the control unit H through the tube via suitable wiring G.

Additionally, a stimulus S can be attached to the support bar Dina different location from but identical in construction to the reference object R. All the adjustments that can made to the reference object R can also be made to the stimulus S, including moving the stimulus towards and away from the person P by means of a telescopic or adjustable tube M attached to the stimulus, which slides in and out of an aperture in the support bar D, or by whatever mechanism it is attached to the support bar, as indicated by the bidirectional arrow, or rotating S with respect to the tube around a central pivot. A suitable lever and locking system ensures the stimulus S is stabilised in the desired position. The tube M also carries the power supply, and where relevant the image signal, from the control unit H via suitable cabling K. The stimulus S is positioned on the support bar D such that its front face lies parallel to the surface of the bar at point at which it is attached.

The stimulus S is attached to the support bar D in such a way that the operator can move the stimulus around the arc defined by the bar in increments of l², as indicated by the dashed line bidirectional arrow. A suitable lever and locking system ensures the stimulus S is stabilised in the desired position until manually released.

The control unit H contains the power supplies, regulators, computational devices, or any other devices necessary to operate the device.

In a further embodiment, multiple stimuli S are attached to the support bar D, the number being conditional on the size of the component housing the stimulus S, the dimensions of the bar, and the total number of stimuli required by the operator. Each stimulus is positioned on the support bar D such that its front face lies parallel to the surface of the bar at point at which it is attached.

In a further embodiment, the support bar D comprises two arcs, one extending up to 100²from the central axis and another extending 70² from the central axis, arranged in the fashion of clock hands, and independently moveable to cover the maximum range of the visual field of the person P while not being obstructed by the person's body when seated in the apparatus.

All components lying within the visual field of the person P and not intended to be visible to the person are painted or coated with a black paint, or other suitable light absorbing substance.

The reference object R is used as the point of visual fixation for the person P during any given test. Beyond controlling the properties of the reference object R, the reference object and also the point of visual fixation of the person P may be further changed. The reference object and by association the point of visual fixation of the person P may be selected as one of the stimuli S at another position on the support bar D for any given test. This selection is instead of the reference object R being located at the centre of the support bar D. Thus one of the stimuli S may become reference object R and also the point of visual fixation of the person for a separate test. The reference object R may then be used as a stimuli S. The reference object R and stimuli S can be identical in construction to facilitate altering the position of the reference object and point of visual fixation of the person.

In use the invention can present to the central visual field of a person P, suitably positioned and stabilised, a reference object R of any practically achievable size, shape, image, luminosity, colour and distance, and one or more stimuli of equal variety at any desired position in the peripheral visual field, and at any desired depth, in increments of either 12 or 1 mm. Moreover, where the device is contained in a lightproof box L only the light from the stimulus S will be visible, and the person P will not be able to perceive the internal physical structure of the device.

Figure 2 is a side elevation diagram showing a device 20 comprised of the main components and operational functions of one embodiment of the second aspect of the present invention. In this embodiment, a person P, who is a patient or experimental participant, is seated in a chair C that is adjustable for height via a suitable mechanism, as indicated by the bidirectional arrow, and equipped with an optional headrest or head restraint that acts to maintain the position and stability of the person's head. The height of the chair is adjusted such that the height of the centre of either of the person's pupils is perpendicular to the centre of the device occupied by the reference object R, shown by line X. An adjustable chin rest A may be provided that stabilises the person's head at the correct position with respect to the device, as indicated by the bidirectional arrow. A light proof screen L fitted with a viewing aperture masks the internal components of the device from person until they are is seated correctly, and also prevents external light entering the stimulus area of the device. A blanking window is fitted over the aperture that is opened only while measurements are being taken.

The main element of the device consists of one or more hemispherical support bar(s) D, which geometrically is a 1802, 1902 or 2002 arc, affixed at its centre point to a rigid support frame F. The support bars D are presented in concave orientation to the person P. The support bar D is attached to a frame F in such a way that the support bar D can be rotated around its affixation point to the extent of 452 clockwise or 452 anticlockwise in increments of 12 via a suitable stepper motor M powered and controlled from the control unit H, as indicated by the curved bidirectional dashed line arrow. As the support bar D rotates it moves freely with respect to the light proof screen L. The support bar D may be fabricated from any suitable material, such as metal, wood, plastic, or a compound of materials. The support bar D may be of any size, the chosen size being determined by practical considerations such as the desired depth and breadth of measurements of visual space perception required, or the available laboratory or clinical examination space.

In this embodiment, the support bars D form a structure which comprises two bars wherein there are two arcs, one extending up to 1002 f_rOm the central axis and another extending 702 from the central axis, arranged in the fashion of clock hands, and independently moveable to cover the maximum range of the visual field of the person P while not being obstructed by their body when seated in the apparatus.

Located at the centre of the support structure D facing the person is a reference object R, the height centre of which is positioned in line with the height centre of the person's pupil. The reference object R is an illuminated object that can be adjusted in size, shape and position relative to the person P, as indicated by the bidirectional arrow.

In one embodiment, the reference object R is a unit constructed using a sheet of electroluminescent material or an arrangement of LED bulbs or other light source in front of which is attached a slot into which light proof masks can be mounted in order to create any desired illuminated shape. In addition, images printed onto transparent or translucent material may be mounted in order to create an illuminated image visible to the person P. In addition, coloured gels may be mounted to alter the colour of the reference object R visible to the person. The luminance of the reference object R can be controlled by a suitable circuit or resistors attached to the power supply of the light-emitting object. The timing of the illumination of the reference object R can be controlled by a computationally controlled circuit breaking switch, or other suitable control mechanism, such that the operator can turn the illumination on and off at will.

The size of the visible area of the reference object R is modifiable using an adjustable diaphragm or aperture placed in front of the illuminated material, the settings of which are controlled by the operator using a suitable computational control device. In one embodiment of this arrangement, the size of the adjustable diaphragm varies from 1mm to 20mm, creating an illuminated disc of this varying size.

The size of the visible area of the reference object R is modifiable using an illuminated inflatable bladder, the settings of which are controlled by the operator using a suitable computational control device. In one embodiment of this arrangement, the size of the inflatable bladder varies from 1mm to 20mm, creating the appearance of an illuminated disc of this varying size to the person P.

In another embodiment, the reference object R is a unit constructed using a video display device, such as an LCD or LED screen, or similar device, on which images can be displayed from a suitable source, such as a computer. This unit is fitted with a slot into which the items noted above are mounted. The operator controls the luminance and exposure time of the light emitted from the reference object R by adjusting the image source signal via a suitable computational control system. In one embodiment, the screen is located behind an adjustable diaphragm or aperture, controlled by a suitable computational control device and the size of the adjustable diaphragm varies from 1mm to 20mm, creating an illuminated display image of this varying size.

The reference object R is attached to frame F, via bar D, by means of a tube integrated into the frame F and holding the reference object R in position. The reference object R can be moved towards and away from the person P using a suitable stepper motor, or gear or cog action, powered and controlled by the control unit H in increments of 1 mm, as indicated by the bidirectional arrow. The electrical power for the reference object R, and where relevant the image signal, is passed from the control unit H through the tube via suitable wiring.

In one embodiment multiple stimuli S identical in construction to the reference object R, are attached to structure D in different locations around the arc of the bars D. The number of stimuli attached is conditional on the size of the component housing stimuli S, the dimensions of the bars, and the total number of stimuli required by the operator.

All the adjustments that can made to the reference object R can also be made to the stimuli S, including changing its size, shape, colour, etc., and moving the stimuli S towards and away from the person P by means of a motorised ratchet mechanism or telescopic mechanism M controlled via a suitable computational control system, which moves the tube T attached to the stimuli S in and out of a suitable fixing in the bars D, or by whatever mechanism it is attached to the bars D as indicated by the dashed line bidirectional arrows. A suitable locking system ensures the stimuli S are stabilised in the desired position. The tube T also carries the power supply, and where relevant the image signal, from the control system H via suitable cabling K. The stimuli S are positioned on the bars D such that its front face lies parallel to the surface of the bars D at the point at which it is attached.

Each stimuli S is attached to the bars D in such a way that the operator can move it around the arc defined by the bars D in increments of l², as indicated by the dashed line bidirectional. A suitable lever and locking system ensures the stimuli S is stabilised in the desired position until manually released.

The control unit H contains the power supplies, regulators, computational devices, or any other devices necessary to operate the device. The operator O of the device controls the control unit H via a suitable computer system, comprising a central processor, memory storage, and an image display screen, which uses suitable software, to control the mechanical and electronic functions of the device embodying the invention.

A calibration tool Q is connected via suitable wiring to the control unit, which can be located at the same viewing position as the person P when the person is absent, and which can measure the size, distance, luminance and other physical properties of the device to ensure all variable properties are correctly calibrated, this being controlled by a suitable calibration system programmed into the control unit.

A user input device W is provided that allows the person P to directly input responses to the stimuli S. In one embodiment, this consists in a mechanical slider that sends an electronic signal to the control unit H representing the value recorded by the person P. In another embodiment, the user input device W consists in a set of buttons or a keyboard or a touch screen that sends an electronic signal to the control unit H representing the values recorded by the person P.

In another embodiment, an eye-tracking unit I is attached to the bars D, which is used to track the behaviour of the person's eyes, and send data to the control unit H via suitable wiring.

All components lying within the visual field of the person P and not intended to be visible to the person P are painted or coated with a black paint, or other suitable light absorbing substance.

In use the device can present to the central visual field of a the person P, suitably positioned and stabilised, a reference object R of any practically achievable size, shape, image, luminosity, colour and distance, and one or more stimuli of equal variety at any desired position in the peripheral visual field, and at any desired depth, in increments of either I² or 1mm.

Figure 3 is a side elevation diagram showing the main components and operational functions of a further embodiment 30 of the second aspect of the invention. In this embodiment, all the components and functionality of the device described in Figure 2 are included, with the exception that support is a hemispherical dome rather than an arc, and the reference object R and the stimuli S are permanently affixed to the internal surface of the dome D and cannot be changed in position with respect to dome D.

Figure 3 shows the configuration of the stimuli S with respect to dome D. In this embodiment, the operator O can adjust the size, shape, luminance, colour, etc. of each stimuli S via the computer system and control unit H and can rotate the dome D to alter the position of each stimuli S with respect to the person P using a suitable control mechanism, but not alter the position of each stimuli S with respect to the dome D.

Figure 4 is a diagram of one embodiment of the invention, showing an example layout 40 of the stimuli in the hemispherical dome D referred to in Figure 3. The hemispherical shape of the dome, seen here in concave orientation, is indicated using lines of latitude and longitude at intervals of 30^. The central reference object R is shown and all the stimuli S are shown distributed throughout the internal surface of the hemisphere. Other quantities of stimuli and geometrical distributions of stimuli may be used in the design, as determined by the requirements of the operator. The reference object R may also be interchanged with any of the stimuli S.

Figure 5 is a flow chart 500 illustrating the main steps 510 in the method, and the supplementary steps 520 in the method.

1. The first main step 511 is to seat and position the person P in the device, using the chair, chin and head adjustments to ensure the person's eyes are lined up correctly with the reference object R. Prior to this, the operator O may have calibrated the device using the tools provided, or this step may be applied automatically if the device is equipped with a suitable auto-calibration tool 521. At this stage the person P would not be visually aware of the internal structure of the device.

2. In a further step 512, the operator O selects the region of the visual field of the person P to be tested, a decision that may be made for experimental or clinical reasons. This region is then targeted by selecting the appropriate stimulus S, including its size, shape, luminance, colour or other visible property that might affect the outcome of the test. Depending on which embodiment of the system is being used, the support structure D might be rotated, or the stimulus S moved, either manually or electromechanically, to the desired position 522.

3. In a further step 513, the operator O instructs the person P to visually fixate on the reference object R, and this can be detected on a device equipped with an eye tracker 523. The operator may also adjust the visible size of the reference object, or some other visible property of the reference object, once the person is in a position within the device to provide feedback about the visible properties of the reference object 523. The method may be used to test both the monocular visual field and the binocular visual field, in the former case by occluding one eye during the measurement.

4. In a further step 514, the operator O stimulates the peripheral visual field of the person P with stimuli S by applying the correct control switch, electrical current, or signal to the illuminated component of the stimuli S, either manually via a suitable mechanical device, or electronically via the computer system and control unit H. The duration, illumination and other properties of the stimuli S may also be set 524.

5. In a further step 515, the person P is instructed to respond by indicating to the operator O their judgement as to the perceived difference between the reference object R and the stimuli S, either by selecting by means of a verbal response or a key or button press a discrete value pertaining to which of the reference object or stimuli has the greater or lesser degree of whichever visual property is being manipulated, or a variable value by moving a slider to adjust the stimuli so it matches the reference object in respect of whichever visual property is being manipulated. Alternatively, in cases where the device embodying the method is equipped with more than one stimuli S, the perceived properties of the different stimuli can be compared and recorded, or in cases where the device embodying the method is equipped with stimuli that can be moved along the arc of support structure D, then the perceived relative distances may be recorded 525.

6. In a further step 516, the response of the person P to the stimulus is recorded, either verbally or through the user input device, which may record variable responses through a suitable mechanical or electromechanical slider or discrete responses through buttons or a keyboard 526.

If the operator O wishes to take more measurements the method is repeated from step 2 onwards, each time adjusting one or more of the visible properties of each stimuli S to obtain measurements under different conditions 51R.

7. In a further step 517, once each measurement is taken, data is generated, either manually by the operator O or computationally using the computer system and control system, and stored in a suitable format 527.

8. In a further step 518, once all the data is collected, a suitable mathematical analysis is conducted, either manually or computationally, to provide a profile of the person's P individual judgements of visual space perception 528.

Claims

1. An apparatus for measuring space perception in the human visual field of a subject (P) comprising:

2. The apparatus of claim 1, further comprising an adjustable chair (C) and adjustable chin rest (A) for the subject.

3. The apparatus of any previous claim, further comprising a light proof screen (B) with a size-adjustable viewing aperture masking the features of the apparatus from the subject until they are seated correctly and minimizing external light entering the apparatus.

4. The apparatus of any previous claim, further comprising a lightproof box (L) which encompasses the apparatus.

5. The apparatus of any previous claim, wherein the support structure (D), is hemispherical or is geometrically an 180° to 200° arc.

6. The apparatus of any previous claim, further comprising a stand (F), wherein the centre of support bar (D) is attached to the stand and the support bar (D) is rotatable around its attachment point 452 clockwise or 452 anticlockwise.

7. The apparatus of any previous claim, wherein the support bar (D) is rotated using a lever (E) to rotate in 1° increments.

8. The apparatus of any previous claim, wherein the reference object (R) is positioned inline with the height centre of the pupils of the subject (P).

9. The apparatus of any previous claim, wherein the reference object (R) or one or more stimuli (S) is a light source.

10. The apparatus of any previous claim, wherein the reference object (R) or one or more stimuli (S) is provided with a mask to produce illuminated shapes or images.

11. The apparatus of any previous claim, wherein the reference object (R) or one or more stimuli (S) is provided with colour changing material.

12. The apparatus of any previous claim, wherein the luminance of the reference object (R) or one or more stimuli (S) can be controlled.

13. The apparatus of any previous claim, wherein the timing of the illumination of the reference object (R) or one or more stimuli (S) can be controlled.

14. The apparatus of any previous claim, wherein the reference object (R) or one or more stimuli (S) has an adjustable aperture placed in between the reference object and subject to control the visible size of the reference object or one or more stimuli to the subject, the adjustable aperture having a diameter in the range of substantially 1mm to 20mm.

15. The apparatus of any previous claim, wherein the reference object (R) or one or more stimuli (S) comprises a video display device.

16. The apparatus of any previous claim, wherein the reference object (R) or one or more stimuli (S) can be moved closerand further from the subject (P).

17. The apparatus of any previous claim, wherein the one or more stimuli (S) is identical in construction to reference object (R).

18. The apparatus of any previous claim, wherein the one or more stimuli (S) can be located at any position on the support bar (D).

19. The apparatus of any previous claim, wherein the each of one or more stimuli (S) are placed in different positions.

20. The apparatus of any previous claim, wherein the support structure (D) comprises two arcs and the two arcs are positioned one extending upward to 100° from the central axis and the other extending upward to 70°from the central axis.

21. The apparatus of any previous claim, further comprising a control unit (H) to operate the apparatus.

22. The apparatus of any previous claim, wherein electrical power and image signal is passed to the reference object (R) or one or more stimuli (S) from a control unit (H) via wiring (G).

23. The apparatus of any previous claim, wherein all components lying within the visual field of the subject and not intended to be visible are coated in light absorbing material.

24. A system of measuring space perception in the human visual field of a subject comprising:

a reference object, wherein the reference object has modifiable properties;

a subject response collection means; and, a control unit configured to;

control the support structure and the modifiable properties of the reference object and one or more stimuli, receive the subject response, analyse the responses to determine the space perception of the subject.

25. The system of claim 24, further comprising an adjustable chair and adjustable chin rest.

26. The system of claim 24 or 25, further comprising a light proof screen with a viewing aperture masking the features of the system from the subject until they are seated correctly and preventing external light entering the system and a removable blanking window for placing over the aperture when measurements are not being taken.

27. The system of any claim 24 to 26, wherein the rotatable support structure comprises one or more spherical wedge shaped support bars.

28. The system of any claim 24 to 27, further comprising a stand, wherein the centre of the support structure is attached to the stand.

29. The system of any claim 24 to 28, wherein the support structure is rotatable around its attachment point 45^ clockwise or 45^ anticlockwise.

30. The system of any claim 24 to 29, wherein the support structure has an automatic rotating means to rotate in 1° increments.

31. The system of any of claim 24 to 30, wherein the modifiable properties of the reference object are, one or more of: size, shape, illumination, colour, relative position to the subject.

32. The system of any of claim 24 to 31, wherein the modifiable properties of the stimuli are, one or more of: size, shape, illumination, colour, relative position to the subject.

33. The system of any of claim 31 or 32, wherein the relative position of the reference object and one or more stimuli to the subject are controlled by a mechanical movement means.

34. The system of any of claim 24 to 33, further comprising a calibration tool, to detect the features of the system and set the systems modifiable properties.

35. The system of any of claim 24 to 34, wherein the subject response collection means comprises, a manual input device.

36. The system of any of claim 24 to 35 wherein the subject response collection means comprises, an eye tracking device.

37. The system of any of claim 24 to 36, wherein the rotatable support structure is a hemispherical dome.

38. The system of the previous claim, wherein the one or more stimuli are permanently affixed to the dome.

39. A method of measuring space perception in the human visual field of a subject comprising the sequence of steps:

(2) selecting a region of a subject's vision to test;

(3) the subject fixates on a reference object;

(4) stimulating the subjects peripheral visual field with stimuli;

(5) gathering the subjects response to the stimuli;

(6) recording the responses;

(7) generating a set of data according to the subjects response;

40. The method of claim 39, wherein the steps (2) to (6) are repeated to cover multiple regions of a subject's vision.

41. The method of claim 39 or 40, wherein step (1) aligning the subject may be performed automatically.

42. The method of any claim 39 to 41, wherein step (2) includes determining a range of properties for the stimuli and the rotation of the measurement apparatus in response to the selected region.

43. The method of any claim 39 to 42, wherein step (3) the fixation can be detected by use of an eye tracker.

44. The method of any claim 39 to 43, wherein during step (3) properties of the reference object are modified.

45. The method of any of claim 39 to 44, wherein the step (4) stimulation can be controlled based in the determined range of properties of the stimuli and rotation apparatus.

46. The method of any claim 39 to 45, wherein during step (5) the subject's response can be a discrete or variable measurement.

47. The method of any claim 39 to 46, wherein in step (6) the response can be recorded automatically or manually from the subject.

48. The method any claim 39 to 47, wherein in step (7) the set of data is generated and stored in a computer system.

49. The method any claim 39 to 48, wherein step (8) comprises mathematical analysis of the set of data, either manually or computationally, to provide a profile of the subjects individual judgements of visual space perception.