Device for performing sap perimetry

Abstract

The invention relates to the field of ophthalmology and is intended for testing the differential light sensitivity of the retina in different areas of the visual field using SAP perimetry. The present device comprises a unit for generating stimuli and establishing a testing procedure, a unit for displaying stimuli, and a feedback unit. The unit for generating stimuli and establishing a testing procedure generates diagnostic stimuli and establishes a topographical model of diagnostic stimuli which is based on a radial coordinate system and is a grid of lines that is formed by radial rays originating from the centre of the retina and by concentric circles, the centre of which is also situated at the centre of the retina. The stimuli are situated at the nodes of intersection of the radial rays with the concentric circles. The result of the invention is an increase in the reliability of testing of the differential light sensitivity of the retina of the eye using SAP perimetry, and an increase in the accuracy of detection of potential central visual field defects caused by depression of the light sensitivity of the retina.

Description

[0001] DEVICE FOR CONDUCTING SAP PERIMETRY

[0002] Field of technology to which the invention relates

[0003] The invention relates to the field of medicine (in particular, but not only, ophthalmology), as well as for determining professional suitability, in particular, but not only, sports, driving vehicles and complex systems, etc. and is intended for conducting a study of differential light sensitivity of the retina in various areas of the visual field, using the SAP-perimetry (Standard Automated Perimetry) method.

[0004] State of the art

[0005] The ability of the eye to distinguish light and fix objects of different brightness under a certain background illumination is called differential light sensitivity. One of the most common methods for studying the differential light sensitivity of the retina at different points within the visual field is perimetry. The results obtained during perimetry are of great importance in diagnosing various diseases, in particular glaucoma. It is known that in glaucoma, early changes more often occur in the central zone of the visual field [Erichev V.P., Antonov A.A., Vitkov A.A., Grigoryan L.A. Static perimetry in the diagnosis of glaucoma. Part 1. Basic principles. Bulletin of ophthalmology. 2021 ;137(5):281-288. https: / / doi.org / 10.17116 / oftalma2021137052281]. This is due to the uneven distribution of ganglion cells in the retina.The central zone contains approximately 66% of the ganglion cells and receives 83% of all information entering the visual area of ​​the brain.

[0006] SAP perimetry (Standard Automated Perimetry) is the standard and most common type of perimetry, which uses stimuli in the form of small luminous dots of a round shape and a given size to assess the visual field function. Stimuli of five sizes with a diameter from 6.5 to 104 arc minutes are used for the test, traditionally they are designated by Roman numerals from I to V. As a rule, a stimulus of size III (26 arc minutes) is used in patients with good (normal or close to normal) visual acuity. In cases of decreased visual acuity, stimuli of size V (104 arc minutes) are used. The background and stimuli are predominantly white, but there are also modifications with colored stimuli on a colored background. The concept of stimulus topography in SAP perimetry (Standard Automated Perimetry) refers to the distribution of stimuli used in this method of studying the visual field.

[0007] From the state of the art, the SAP (Standard Automated Perimetry) perimeter of the "Humphrey Field Analyzer II" (HFA II) is known

[0008] [https: / / www. zeiss. fr / content / dam / Meditec / international / ifu / documents / hfa3 / current / 2660021166144 _a_artwork.pdf]. The device is a stationary hardware and software complex designed to study the differential light sensitivity of the eye using the SAP perimetry method. Visualization of stimuli occurs on a screen located in the stationary housing of the device. Also known from the prior art are solutions in which visualization of stimuli occurs on a screen located in a head-mounted device housing, for example, the SAP VR perimeter PALMSCAN VF2000 from MicroMedicalDevices [https: / / micromedinc.com / vf2000-visual-field-analyzer / ] or the SAP VR perimeter AVA developed by Elisar [https: / / www.elisar.com].

[0009] The disadvantage of these and similar devices is the uneven study of the differential light sensitivity of the retina in different areas of the visual field. This disadvantage occurs due to the fact that the tested ganglion cells are unevenly distributed on the retina. The density of these cells increases significantly towards the center. At the same time, their density in the nasal area is greater than in the temporal area. At the same time, the frequency (density) of the distribution of stimuli during the study is always the same. Thus, each stimulus tests the field in a segment (square) in which a different number of tested ganglion cells are located, which can lead to a decrease in the "sensitivity" parameter of the study during screening and insufficiently high accuracy of determining the differential light sensitivity of the retina during the threshold study.Numerous publications show that when conducting a study of differential light sensitivity of the retina by the standard (white stimulus on a white background) perimetry method, it is possible to record disturbances only when at least a certain percentage of retinal ganglion cells (25-35%) die. Thus, when a certain number of cells die, this percentage can be reached and detected in the peripheral (or temporal) areas, where the cell density is lower, and, consequently, the percentage of dead cells is higher with an equal number of them, and is not reached, and, consequently, is not detected closer to the center of the retina (or in the nasal area), where the density of ganglion cells is higher, and, consequently, the percentage of dead cells is lower with an equal number of them.

[0010] In most currently existing SAP perimeters, the test topography is based on the Cartesian (orthogonal) coordinate system. The diagnostic stimuli are located at the corners of a grid consisting of squares. All grid squares have the same size, most often 6x6 angular degrees. The size of the visual field under study is usually 24 or 30 degrees from the center of the retinal macula. The field under study has the shape of a truncated rhombus, with corners oriented along the coordinate axes, respectively, 48 or 60 angular degrees. The principle of constructing the study topography known from the prior art is that all stimuli are placed uniformly over the entire area of ​​the field under study, in the corners of a grid consisting of square cells, which allows for uniform examination of retinal segments identical in size and shape, but each stimulus has a different and multidirectional distance from the center of the retina.

[0011] Disclosure of the essence of the invention

[0012] The technical task is to create a SAP-perimeter device with an original topographic model of stimulus distribution based on a radial (polar) coordinate system, designed in such a way that each stimulus is placed in a segment of the retina containing approximately the same number of ganglion cells being studied, which makes it possible to detect with equal probability disturbances in the differential light sensitivity of the retina in each segment being studied with the death of an almost equal number of ganglion cells, which in turn increases the reliability of the study of differential light sensitivity of the retina using the SAP-perimetry method.

[0013] The technical result consists in increasing the reliability of the study of differential light sensitivity of the retina of the eye using the SAP-perimetry (Standard Automated Perimetry) method, increasing the accuracy of detecting defects arising due to depression of the light sensitivity of the retina.

[0014] The technical result is achieved due to the fact that the SAP perimeter with a topographic model of stimuli based on a radial (polar) coordinate system contains a stimulus generation and test procedure formation unit, a stimulus visualization unit and a feedback unit, which are interconnected, wherein the stimulus generation and test procedure formation unit is designed with the possibility of generating diagnostic stimuli and forming a topographic model of diagnostic stimuli based on a radial (polar) coordinate system, which is a grid of lines formed by radial rays originating in the center of the retina and concentric circles with a center also formed in the center of the said retina, wherein the stimuli are located at the intersection nodes of the radial rays and concentric circles.

[0015] In addition, the intersections of the grid lines form areas that are curvilinear trapezoids, the area of ​​which increases with distance from the center.

[0016] In addition, the grid areas shaped as curvilinear trapezoids can be designed in such a way that their area decreases in the nasal region. In addition, additional grid areas can be introduced, and therefore additional stimuli in the nasal region.

[0017] In addition, the SAP perimeter additionally contains a block for monitoring the execution of the study, which can be performed either in a single block with the block for generating stimuli and forming the test procedure, or separately;

[0018] In addition, the SAP perimeter additionally contains a block for analyzing the obtained results and generating the probability of a diagnosis, which can be performed either in a single block with a block for generating stimuli and generating a test procedure or with a block for monitoring the execution of the study, or separately;

[0019] In addition, the feedback unit can be implemented in the form of a button that provides a yes / no response from the subject, or in the form of a joystick that controls the response in the form of movement in space, or in the form of a neurointerface that controls the change in signals in the channels of visual analyzers, or in the form of a device that analyzes visual reactions;

[0020] In addition, the blocks are connected to each other by wired communication and / or by using wireless information transmission technology.

[0021] In addition, wireless information transmission technology is implemented via Wi-Fi, Bluetooth or 1oT.

[0022] In addition, the SAP perimeter can be made either stationary or with the ability to be placed on the head, in the form of a virtual reality helmet or augmented or mixed reality glasses.

[0023] Brief description of the drawings

[0024] The details, features, and advantages of the present invention follow from the following description of the claimed technical solution using the drawings, which show:

[0025] Fig. 1 - Block diagram of the device. The dotted line indicates optional blocks;

[0026] Fig. 2 - Density of ganglion cells depending on their distance from the center of the retina. Data obtained from the source - Christine A. Curcio et al. [Human Photoreceptor Topography.

[0027] Fig.3 - Stimulus topography based on the Cartesian (orthogonal) coordinate system, using the perimeter of the Humphrey® Field Analyzer 3 (HFA3) as an example.

[0028] Fig. 4 - Technically known topography of SAP perimetry stimuli based on the Cartesian (rectangular) coordinate system. The distance between stimuli is 6 angular degrees. Additional stimuli in the nasal region are not shown.

[0029] Fig. 5 - Curve of cell density change used in calculating the area of ​​the curvilinear trapezoidal stimuli. The data for plotting the curve were obtained from Table 1 of the source - Sjostrand, J., Olsson, V., Popovic, Z., & Conradi, N. (1999). Quantitative estimations of foveal and extra-foveal retinal circuitry in humans. Vision Research, 39(18), 2987-2998. doi:10.1016 / s0042-6989(99)00030-9. The diagram shows the fourth-degree trend line polynomial y=f(x) used in the calculations and its reliability value R.

[0030] Fig. 6 - Conventional number of ganglion cells in each square zone adjacent to the stimulus depending on its location relative to the center (macula) of the retina in the topography of SAP perimetry stimuli based on the Cartesian (rectangular) coordinate system. The squares are 6x6 angular degrees. Such uneven distribution of cells can lead to a decrease in the "sensitivity" parameter of the study during screening and insufficiently high accuracy of determining the loss of differential light sensitivity of the retina during a threshold study.

[0031] Fig. 7 - Example of a topographic model of stimuli based on a radial (polar) coordinate system. The stimuli are located at the intersections of uniformly distributed radial rays originating in the center of the retina and concentric circles also centered in the center of the retina.

[0032] Fig. 8 - Conditional number of cells in each zone adjacent to the stimulus depending on its location relative to the center of the retina in the topography of SAP perimetry stimuli based on the proposed radial grid (coordinate system) without correction of the nasal regions. It is evident that in all sectors (stimuli) the number of cells is the same with the exception of the nasal regions.

[0033] The following positions are indicated by numbers on the figures:

[0034] Pos. 1 - Block for generating stimuli and forming the test algorithm;

[0035] Pos. 2 - Stimulus visualization block;

[0036] Pos. 3 - Feedback block;

[0037] Pos. 4 - Block for monitoring the execution of the study;

[0038] Pos. 5 - Block for analyzing the obtained results and forming the probability of diagnosis;

[0039] Pos. 6 - Density of ganglion cells in the nasal and temporal regions at a distance of less than 1 mm;

[0040] Pos. 7 - Density of ganglion cells in the nasal and temporal regions at a distance of less than 20 mm (the graph shows that the density in the nasal region is higher);

[0041] Pos. 8 - Density of ganglion cells in the superior and inferior regions at a distance of less than 1 mm;

[0042] Pos.9 - Density of ganglion cells in the superior and interior regions at a distance of less than 20 mm; Pos.10 - Grids of 76 stimuli (test 30-2) and 54 stimuli (test 24-2) using the prior art Humphrey® Field Analyzer 3 (HFA3) perimeter as an example with additional stimuli in the nasal region. The step between stimuli is 6 angular degrees;

[0043] Pos.11 - Example of printed form of the test result on the perimeter of the "Humphrey® Field Analyzer 3 (HFA3). Test 24-2;

[0044] Pos.12 - Decoding the test results on the grid above;

[0045] Pos.13 - Stimuli arranged on a grid in the orthogonal Cartesian coordinate system. 54 stimuli, step - 6 degrees, study area - 24 degrees from the center of the retina. This is the Humphrey® 24-2 test without additional stimuli in the nasal area;

[0046] Pos.14 - Conventional number of ganglion cells in each square zone adjacent to the stimulus depending on its location relative to the center of the retina in the topography of SAP perimetry stimuli based on the Cartesian (rectangular) coordinate system. The square sizes are 6x6 angular degrees. Such uneven distribution of ganglion cells may result in a decrease in the "sensitivity" parameter of the study during screening and insufficiently high accuracy of determining the loss of differential light sensitivity of the retina during a threshold study;

[0047] Pos.15 - Nasal region (N);

[0048] Pos.16 - Temporal region (T);

[0049] Pos.17 - Blind spot;

[0050] Pos.18 - Grid of the radial (polar) coordinate system. Uniformly distributed radial rays originating in the center of the retina and concentric circles with a center also in the center of the retina;

[0051] Pos.19 - Stimuli located at the intersection nodes of uniformly distributed radial rays originating in the center of the retina and concentric circles also centered in the center of the retina, in a topographic model based on a radial (polar) coordinate system;

[0052] Pos.20 - Conventional number of ganglion cells in each zone, having the shape of a curvilinear trapezoid and adjacent to the stimulus, depending on its location relative to the center of the retina with the topography of SAP perimetry stimuli based on the proposed radial grid (coordinate system) without correction of the topography in the nasal areas. It is evident that in all sectors (stimuli) the number of ganglion cells is the same, with the exception of the nasal areas, in which ganglion cells are located with a density increased by 42%;

[0053] Pos.21 - Conventional number of ganglion cells in the nasal region, in each zone having the shape of a curvilinear trapezoid and adjacent to the stimulus, depending on its location relative to the center of the retina with the topography of SAP perimetry stimuli based on the proposed radial grid (coordinate system) without correction of the topography in the nasal regions. It is evident that in the nasal regions the number of ganglion cells increases by 42% on average.

[0054] Implementation of the invention

[0055] The claimed device is intended for conducting SAP perimetry (Standard Automated Perimetry) with the topography of diagnostic stimuli based on the radial (polar) coordinate system. Regardless of the design features (stationary or mobile), the device is a hardware and software complex capable of performing a full set of actions necessary to determine the differential light sensitivity of the retina and detect possible defects in the central field of vision that arise due to depression of the light sensitivity of the retina. Or, in other words, a hardware and software complex capable of performing a full set of actions that fit the definition of "SAP perimetry".In addition, if necessary (but not necessarily), based on the results of the studies, the device is able to determine, based on embedded algorithms or a specially trained machine learning (ML) or artificial intelligence (AI) system, the probability of the presence of a particular disease and / or its stage.

[0056] The device consists of a stimulus generation and test procedure formation unit, a stimulus visualization unit, and a feedback unit. Additionally, there may be a study execution control unit and a unit for analyzing the obtained results and forming the probability of diagnosis.

[0057] As stated earlier, unlike known solutions, the claimed device is capable of generating stimuli for conducting SAP perimetry using a topographic model of stimuli based on a radial (polar) coordinate system.

[0058] The topography of stimuli in SAP perimetry includes the following main characteristic - arrangement: SAP perimetry stimuli are arranged on a special grid or matrix, which allows the required area of ​​the visual field to be examined. The arrangement of stimuli can be adapted to the specific needs of the study.

[0059] The essence of the proposed solution for the topography of SAP perimetry stimuli concerns such a parameter as the location of stimuli and is based on the results of two known types of studies: 1. The studied ganglion cells are located unevenly on the retina. The density of these cells increases significantly towards the center. In addition, their density in the nasal region is greater than in the temporal region (Fig. 2);

[0060] 2. When conducting a study of differential light sensitivity of the retina using the perimetry method, it is possible to record disturbances in the central visual field only when at least a certain percentage (or share) of the studied ganglion cells die. In other words, it is not the number of dead cells that matters, but their percentage (or share) relative to those being studied at the given moment using one stimulus.

[0061] Let's take a closer look.

[0062] The first type of research is counting the number of ganglion cells in different areas of the retina. In 1990, Christine A. Curcio et al. published an article [Human Photoreceptor Topography], and in 1999, Johan Sjostrand et al. published an article [Quantitative estimations of foveal and extra-foveal retinal circuitry in humans], in which they provide figures and visual graphs showing an increase in the density of ganglion cells as they approach the center of the retina. According to the published data, at a distance of 2 degrees from the center of the retina, the density of ganglion cells is 16 times greater than at a distance of 20 degrees. It is also shown that in the nasal region, the density of ganglion cells is 42% higher than in the temporal region. Similar results have been published based on the results of a number of other studies [Curcio CA, Allen KA. Topography of ganglion cells in human retina. The Journal of Comparative Neurology. 1990;300(1):5-25. https: / / doi.Org / 10.1002 / cne.903000103].

[0063] The second type of research provides an understanding that when conducting a study of differential light sensitivity of the retina using the perimetry method, it is possible to record disturbances only when at least a certain percentage of the cells being studied perish. It is generally accepted that perimetric studies with a white stimulus on a white background allow one to record disturbances when more than 25-35% of the retinal ganglion cells perish. In other words, it is not the number of dead ganglion cells that matters, but their percentage (or share) relative to those being studied in a given place using one stimulus.Thus, when a certain number of cells die, this percentage (share) can be achieved and detected in the peripheral (or temporal) region, where the density of ganglion cells is lower, and not achieved, and therefore not detected, closer to the center of the retina (or in the nasal region), where the density of ganglion cells is higher, and, therefore, the percentage of dead cells is lower with an equal number of them.

[0064] The combined effect of these two facts leads to an important drawback of the traditional topography of SAP perimetry stimuli - an uneven study of the differential light sensitivity of the retina in different areas of the visual field.

[0065] Traditional SAP perimetry topography involves the use of a topographic model of stimuli based on the Cartesian (orthogonal) coordinate system. The area to be examined is divided into squares of equal size. Most often, the squares are 6x6 angular degrees. The stimuli are presented to this topographic grid. The number of stimuli in the test depends, in particular, on the size of the field to be examined. The most common grids are 76 stimuli (test 30-2) and 54 stimuli (test 24-2), using the example of the Humphrey® Field Analyzer 3 (HFA3) perimeter known from the state of the art with additional stimuli in the nasal region.

[0066] Since when using the topographic model of stimuli based on the Cartesian (orthogonal) coordinate system, all the squares of the grid on which the stimuli of one test are located have the same area, each square of the grid contains a different number of cells under study, depending on its location relative to the center of the retina, which, as was said above, can lead to a decrease in the "sensitivity" parameter of the study during screening and insufficiently high accuracy in determining the loss of differential light sensitivity of the retina during a threshold study. Thus, with the 24-2 test, with a step of 6 angular degrees, approximately 74,000 cells are placed in each of the four central squares (stimuli), 10,000 cells in the upper, lower and temporal squares, 9,000 cells in the corner squares, and up to 17,000 cells in the nasal squares (Fig. - 6).Accordingly, a perimetric test capable of recording only the death of more than 25-35% of cells will give a result when more than 18,000-26,000 cells die in the central squares; when more than 2,500-3,500 cells die in the upper, lower and temporal squares; when more than 2,000-3,000 cells die in the corner squares; when more than 4,000-6,000 cells die in the nasal squares.

[0067] The given example clearly demonstrates the main drawback of the traditional topography of SAP perimetry stimuli based on the Cartesian (orthogonal) coordinate system - uneven study of the differential light sensitivity of the retina in different zones of the central visual field.

[0068] To eliminate this drawback, it is proposed to use a radial (polar) coordinate system instead of the Cartesian (orthogonal) coordinate system to construct the topography of SAP perimetry stimuli. The baselines of such a system consist of radius vectors originating in the center of the retina and concentric circles with a common center also in the center of the retina. The areas formed as a result of the intersection of these baselines are curvilinear trapezoids, the area of ​​which increases with distance from the center. In addition, the grid areas shaped as curvilinear trapezoids can be made in such a way that their area decreases in the nasal region. In this case, additional grid areas can be introduced, and, consequently, additional stimuli in the nasal region.Accordingly, it is possible to select such parameters of the base lines (radii and circles) that, as the distance from the center of the retina increases, the increase in the area of ​​the sectors compensates for the decrease in the density of the cells under study. With complete compensation, the number of cells under study in each sector (area) will be the same (Fig. 8). This, in turn, will make the study of differential light sensitivity of the retina in different areas of the visual field uniform and eliminate the above-mentioned disadvantage inherent in traditional topography. The nasal area will be an exception. This is due to the fact that the density of ganglion cells in the nasal area is 42% higher and to compensate for it, it will be necessary to increase the density of stimulus placement in the nasal area. An example of a grid based on the radial polar coordinate system is shown in Fig. 8.It is evident that due to the increase in the area of ​​the segments with distance from the center of the retina, the number of ganglion cells located in each sector is the same. The exception is the segments located in the nasal region (Pos. 21), in which a greater number of these cells are located.

[0069] To compensate for the denser location of ganglion cells in the nasal region, two methods can be used:

[0070] 1. the radius vectors are distributed unevenly around the circumference, that is, more densely in the nasal region;

[0071] 2. in the nasal region the height of the curvilinear trapezoids decreases in the direction of the radius vectors.

[0072] This technique allows the creation of multiple stimulus topographies for SAP perimetry depending on the tasks set by the researchers.

[0073] This patent shows a 54-stimuli topography (Fig. 8) without topography correction in the nasal areas. It is intended to replace the traditional 24-2 square grid.

[0074] The given topography is only an example of the use of the proposed topographic model for SAP perimetry based on the radial polar coordinate system and does not exhaust the possibilities of this model.

[0075] To implement the procedure for generating stimuli for conducting SAP perimetry with a topographic model of stimuli based on a radial (polar) coordinate system, the following SAP perimeter elements were used:

[0076] • block for generating stimuli and forming the test procedure;

[0077] • stimulus visualization unit;

[0078] • feedback block.

[0079] Additionally, the following may be present:

[0080] • control unit for the implementation of the study;

[0081] • block of analysis of the obtained results and formation of the probability of diagnosis.

[0082] The stimulus generation and test procedure formation unit is designed with the ability to provide stimulus generation and formation of the research algorithm in accordance with the selected SAP perimetry strategy, using a topographic stimulus model based on the radial polar coordinate system. The stimulus visualization unit is designed with the ability to provide visualization of the stimuli generated by the stimulus generation and test procedure formation unit on a stationary monitor or screen, or, but not limited to, on monitors or screens of a head-mounted device.

[0083] The device may be placed on the head and may be, but is not limited to, in the form of a virtual reality helmet or augmented or mixed reality glasses.

[0084] The feedback unit is designed to provide information about the moment when the patient saw the generated stimulus. The feedback unit can be designed as a button providing a yes / no response, or as a joystick controlling the response in the form of movement in space, or as a neurointerface controlling the change in signals in the channels of visual analyzers, or as a device analyzing visual reactions. The feedback unit can be located in the patient's hands or another part of the patient's body or on the patient's head.

[0085] The combined use of these units enables SAP perimetry with topography of diagnostic stimuli based on the radial polar coordinate system.

[0086] The block for monitoring the execution of the study can be implemented either in a single block with the block for generating stimuli and forming the test procedure, or separately. Using the block for monitoring the execution of the study allows the researcher to monitor the course of the study and, if necessary, make the necessary adjustments.

[0087] The block of analysis of the obtained results and formation of the probability of diagnosis can be performed either in a single block with the block of stimulus generation and formation of the test procedure, or with the block of control over the execution of the study, or separately. Using the block of analysis of the obtained results and formation of the probability of diagnosis allows after the end of the study to obtain an independent "third opinion" on the probability of the presence of a particular diagnosis or its stage.

[0088] Communication between all units is accomplished via wired communication and / or by using wireless information transmission technology.

[0089] Wireless information transmission technology is implemented through, but not limited to, Wi-Fi, Bluetooth, loT.

[0090] In the particular case of implementation of the declared technical solution, the patient and the researcher may be one and the same person.

[0091] Fig. 1 shows a block diagram of the device, which shows a block for generating stimuli and forming the test procedure (Pos. 1), a block for visualizing stimuli (Pos. 2), a feedback block (Pos. 3), and an additional block for monitoring the execution of the study (Pos. 4) and a block for analyzing the obtained results and forming the probability of a diagnosis (Pos. 5).

[0092] Fig. 2 shows the density of ganglion cells as a function of their distance from the center of the retina to the source - Christine A. Curcio et al. Human Photoreceptor Topography.

[0093] Fig. 3 shows some currently known from the art SAP perimetry stimulus topographies. Shown are grids 24-2 (54 stimuli) and 30-2 (76 stimuli) of the prior art SAP perimeter "Humphrey® Field Analyzer 3 (HFA3). - In the solutions known from the art, the test topography is based on a Cartesian (orthogonal) coordinate system. The diagnostic stimuli are arranged on a grid in the form of squares of the same size. All squares have the same size, often 6x6 angular degrees (Pos. 10 and 13), and are arranged close to each other.

[0094] Fig. 4 Pos. 13 - shows in more detail the 24-2 grid (54 stimuli) of the SAP-perimetry stimulus topography technique, known from the Cartesian (rectangular) coordinate system. The distance between the stimuli is 6 angular degrees. Additional stimuli in the nasal region are not shown.

[0095] Figure 5 shows the curve of the change in the density of the ganglion cells used in the calculations of the area of ​​the stimuli in the form of curvilinear trapezoids. The data for constructing the curve were obtained from Table 1 of the source - Sjostrand, J., Olsson, V., Popovic, Z., & Conradi, N. (1999). Quantitative estimations of foveal and extra-foveal retinal circuitry in humans. Vision Research, 39(18), 2987-2998. doi:10.1016 / s0042-6989(99)00030-9. The diagram shows the fourth-degree trend line polynomial y=f(x) used in the calculations and the value of its reliability R.

[0096] Fig. 6 shows the conventional number of ganglion cells in each square area in which the stimulus is located depending on its location relative to the center of the retina in the topography of SAP perimetry stimuli based on the Cartesian (rectangular) coordinate system. The squares are 6x6 angular degrees. Such uneven distribution of ganglion cells can lead to a decrease in the parameter "sensitivity" of the study during screening and insufficiently high accuracy of determining the loss of differential light sensitivity of the retina during a threshold study.

[0097] The principle of constructing the currently known from the state of the art research topography based on the Cartesian (orthogonal) coordinate system is that each stimulus is located in the center of identical in size and shape segments of the retina in the form of squares, most often 6x6 angular degrees in size. But at the same time, each square and, accordingly, the stimulus has a different and multidirectional distance from the center of the retina. The disadvantage of this solution is the uneven study of the differential light sensitivity of the retina in different zones of the central field of vision. This disadvantage is a consequence of the fact that the studied ganglion cells are located unevenly on the retina. The density of these cells increases significantly towards the center. In addition, their density in the nasal region is greater than in the temporal region. This unevenness is illustrated in Fig. 2.where the change in the density of ganglion cells with changing distance from the center of the retina is clearly visible. Pos. 6 - in the nasal and temporal regions at a distance of less than 1 mm; Pos. 7 - in the nasal and temporal regions at a distance of less than 20 mm (the graph shows that their density in the nasal region is higher); Pos. 8 - in the superior and inferior regions at a distance of less than 1 mm; Pos. 9 - in the superior and inferior regions at a distance of less than 20 mm;

[0098] Thus, it is obvious that each segment (square-shaped area) under study contains a different number of cells under study, which may lead to a decrease in the parameter "sensitivity" of the study during screening and insufficiently high accuracy of determining the differential light sensitivity of the retina during a threshold study. Numerous publications show that when conducting a study of differential light sensitivity of the retina by the perimetry method, it is possible to record violations only when at least a certain percentage of the cells under study die (usually the value of 25%-35% is indicated).Thus, when a certain number of ganglion cells die, this percentage can be reached and detected in the peripheral (or temporal) areas, where the density of ganglion cells is lower, and, consequently, the percentage of dead cells is higher with an equal number of them, and not reached, and, consequently, not detected closer to the center of the retina (or in the nasal area), where the density of these cells is higher, and, consequently, the percentage of dead cells is lower with an equal number of them.

[0099] Fig. 7 shows an example of a topographic model of stimuli based on a radial polar coordinate system. The stimuli are located at the intersections of uniformly distributed radial rays originating at the center of the retina and concentric circles also centered at the center of the retina.

[0100] The topography of the stimuli in SAP perimetry is an important aspect of this research method, since it allows obtaining information on the differential light sensitivity of the retina and detecting possible defects or changes in the central visual field arising due to depression of retinal light sensitivity.

[0101] The above-described claimed SAP perimeter solution, containing the said blocks, designed with the ability to generate an original topographic model of stimuli based on a radial polar coordinate system and planned in such a way that each stimulus allows for examining an area of ​​the retina containing approximately the same number of cells being examined, allows for detecting with equal probability disturbances in the differential light sensitivity of the retina in each segment being examined when the same number of cells being examined die, which in turn increases the reliability of examining the differential light sensitivity of the retina using the SAP perimetry method.

Claims

CLAUSE OF INVENTION 1. A SAP perimeter with a topographic model of stimuli based on a radial polar coordinate system, characterized in that it contains a stimulus generation and test procedure formation unit, a stimulus visualization unit, and a feedback unit, interconnected with each other, wherein the stimulus generation and test procedure formation unit is designed with the possibility of generating diagnostic stimuli and forming a topographic model of diagnostic stimuli based on a radial polar coordinate system, which is a grid of lines formed by radial rays originating in the center of the retina and concentric circles with a center also formed in the center of said retina, wherein the stimuli are located at the intersection nodes of the radial rays and concentric circles.

2. The SAP perimeter according to paragraph 1, characterized in that the intersections of the grid lines form areas that are curvilinear trapezoids, the area of which is made to increase with distance from the center.

3. The SAP perimeter according to paragraph 1, characterized in that the intersections of the grid lines form areas that are curvilinear trapezoids, the area of which is made to decrease in the nasal region.

4. The SAP perimeter according to item 1, characterized in that stimuli are additionally performed in the nasal region.

5. The SAP perimeter according to paragraph 1, characterized in that it additionally contains a block for monitoring the execution of the study, which is implemented both in a single block with the block for generating stimuli and forming the test procedure, and separately; 6. The SAP perimeter according to paragraph 1, characterized in that it additionally contains a block for analyzing the obtained results and generating the probability of a diagnosis, which is implemented both in a single block with a block for generating stimuli and generating a test procedure or with a block for monitoring the execution of the study, and separately; 7. The SAP perimeter according to item 1, characterized in that the feedback unit is made in the form of a button that provides a yes / no reaction from the test subject, or in the form of a joystick that controls the reaction in the form of movement in space, or in the form of a neurointerface that controls the change in signals in the channels of visual analyzers, or in the form of a device that analyzes visual reactions; 8. The SAP perimeter according to item 1, characterized in that the blocks are connected to each other by means of a wired connection and / or by using wireless information transmission technology.

9. The SAP perimeter according to paragraph 1, characterized in that the wireless information transmission technology is implemented via Wi-Fi, Bluetooth or loT.

10. The SAP perimeter according to paragraph 1, characterized in that it is made both stationary and with the possibility of being placed on the head, in the form of a virtual reality helmet or augmented or mixed reality glasses.

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