Device for visual inspection, especially for carrying out visual field test

Abstract

To provide a device that can be applied to medicine, especially ophthalmology and is designed for visual inspection.SOLUTION: A device can be used for perimetry / visual field tests and can be used for other parameters with which a test is carried out with light stimulus that is displayed ahead of eyes of a patient.SELECTED DRAWING: Figure 3

Description

Technical Field

[0001] The present invention relates to a device designed for visual examination that can be applied in medicine, particularly in ophthalmology. The device can be used for perimetry or visual field testing, but can also be used for other parameters where the test is performed by light stimuli displayed in front of the patient's eyes.

Background Art

[0002] From the description included in US Patent No. 5,864,384, devices using virtual reality for visual field testing are known. This device enables sending visual information to the visual pathways of the patient's eyes, their retinas, and optic nerves, and measuring and quantifying the visual information from them. The screen, which is part of the device, covers a large visual field in some cases of patients. The computer connection allows controlling the device and selecting the tests and stimuli sent to the patient. Additionally, switches or buttons are available for collecting responses from the patient. By using the screen as a stimulus source, it is possible to display a fixation point anywhere and change the background, luminance, contrast, color, size, details, and duration of the light stimuli. The use of such a device does not require adapting the entire room for testing because the entire visual field of the patient fits within the device. Another alternative is goggles with independent eyepieces that allow the patient to observe the visual field where the test stimulus is presented to one eye at a time. This device uses virtual reality and is worn on the patient's head.

[0003] From the description of International Publication No. WO 2012 / 148983, it is known to use two LCD panels on a screen to improve the contrast of the generated image. By using two LCD panels together with a polarizer system, it becomes possible to achieve a high dynamic range (HDR). In this way, the dynamic range of the device is increased, but at the same time the brightness of the image is reduced, so a brightness increasing element is additionally used. The first screen in the presented technology is a color screen that generates an image, while the other is an achromatic screen that increases the contrast.

[0004] From the description of International Publication No. WO 2018 / 169330, the use of a visual field measurement method is known. This method uses Goldmann III stimuli with different luminance levels that are presented to the patient at least once within different sections of the screen. The device is a head-mounted screen that generates and displays the stimuli. It also includes buttons that enable it to receive the patient's responses, and the device itself collects and stores information about the responses. The device then transmits this information to an electronic device, which identifies and analyzes the sequence of user responses and generates a report regarding the patient's visual field.

[0005] Unfortunately, the solutions existing in the prior art exhibit drawbacks. The luminance levels achievable by display devices are often too low to perform an accurate eye examination. Furthermore, they have an insufficient number of different luminance levels of display points at which the test can be conducted, which also negatively affects the accuracy / quality of the test. Finally, some of the available devices are inconveniently heavy and consume energy unnecessarily.

Prior Art Documents

Patent Documents

[0006]

Patent Document 1

Patent Document 2

[0007] Accordingly, an object of the present invention is to provide an inspection device for the human eye that enables various eye tests to be performed over a wide luminance range, is lightweight, compact, operates comfortably, and exhibits reduced energy consumption during operation. [Means for Solving the Problems]

[0008] The present invention is an eye inspection device, - a housing that includes other components of the device and has a shape adapted to accommodate the user's head, particularly the face, during the test period, - a power supply means for supplying electrical energy to the device, - a display unit for generating an optical signal for performing the test, - an optical system for transmitting the optical signal from the display unit to the patient, - and a cooling system for the display unit. In the eye inspection device, the display unit has the following components arranged in the order given below, namely a lighting layer, at least one luminance enhancement layer, a first polarizing layer, a first liquid crystal modulation layer, a second polarizing layer, a second liquid crystal modulation layer, and a third polarizing layer, wherein the first and second liquid crystal modulation layers are provided with monochrome LCD panels. The present invention relates to an eye inspection device.

[0009] Preferably, the lighting layer is selected from the group consisting of an LED sheet connected to a light directing film and a CCFL panel.

[0010] Preferably, the first, second, and third polarizing layers have a uniform transmittance within the spectral range of visible light, i.e., a transmittance deviation of less than 10%.

[0011] Preferably, both LCD panels have an optical resolution suitable for achieving light stimulation within an area fitting within a solid angle of 4.4 * 10 -5 steradians ± 20% / -15%.

[0012] Preferably, the device has one each of the two display units, the optical system, and the cooling system defined above for each eye.

[0013] Preferably, the optical system is provided with correction lenses properly arranged for each eye and positioned to be movable longitudinally with respect to the eye being tested independently of each other.

[0014] Preferably, both display units are provided with means for moving each of them independently with respect to the eye being tested.

[0015] Preferably, the optical system is provided with means for adjusting the position of the display unit and / or the correction lens, and means for moving them horizontally to adjust the display unit and / or the correction lens according to the user's interpupillary distance.

[0016] Preferably, in the cooling system, more than 50% of the coolant used to cool the display unit is used to cool both LCD panels, and in particular, more than 2 / 3 of the coolant is used to cool both LCD panels, while the remainder of the coolant is configured to be used to cool the illumination layer.

[0017] Preferably, the housing is provided with an adjustable grip for directly attaching the device to the patient's head.

[0018] Preferably, the housing is additionally provided with connection means for attaching the device to the stand.

[0019] Preferably, the power supply means is provided with both an electrical connection for power supply from a main power source and a battery or accumulator directly connected to the device.

[0020] Preferably, the housing has a replaceable and flexible gasket for blocking light coming from outside the device at the spot where the patient brings their face close, during the examination.

[0021] Preferably, the device is adapted and configured to achieve a luminance of 10000 asb ± 25%.

[0022] Preferably, the device has a digital computing system for controlling the operation of the device and for eye examination, which is directly integrated into the device.

[0023] The device described according to the present invention meets the above-defined objectives and significantly improves the ability and simplicity of eye examination.

Brief Description of the Drawings

[0024]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Best Mode for Carrying Out the Invention

[0025] Perimetry implemented using an LCD is known and is used in small perimeters. A proper visual field test requires a high dynamic range and high-brightness stimuli, which are difficult to achieve with existing devices.

[0026] This problem is addressed by a screen 1 that uses two modulation layers 5a, 5b, preferably in the form of an LCD panel, to generate an image together with a set of polarizing layers 4a, 4b, preferably in the form of polarizing plates, which combine to give good representation of black. The screen 1 uses an illumination layer 2, a brightness enhancement element 3, and a set of three polarizing layers 4a, 4b, where the first of the polarizing layers is positioned in front of the first modulation layer 5a, the second is positioned between the LCD modulation layers 5a, 5b, and the last is positioned behind the second modulation layer 5b, as shown in FIG. 1.

[0027] Such a configuration of the screen 1 makes it possible to achieve the dynamic range achieved in conventional perimeters, i.e., between 0 and 48 dB. The high dynamic range can be achieved by using an additional light modulation element in the form of an LCD panel 5b.

[0028] Using two LCD panels for modulation also provides a high dynamic resolution that enables accurate representation of the luminance levels required for eye examinations. The 8-bit monochrome panels applied can each achieve 8 (256) levels of luminance modulation. The set of two panels in the screen 1 makes it possible to achieve 16 (65536) luminance levels over the entire dynamic range of 0 to 48 dB. Such a dynamic resolution makes it possible to meet the requirements of the EN ISO 12866 standard related to perimetry tests, particularly the background luminance tolerance (+25% / -20% of the specified value) and the differential luminance of the stimulus (+25% / -20% of the specified value).

[0029] Furthermore, by using a monochrome LCD panel, the device consumes less energy than a color panel. This further makes it easier to cool the components of the device, particularly the components of screen 1.

[0030] The subject of the present invention enables eye examinations consisting of dynamic perimetry and static perimetry, the Amsler test, distance visual acuity tests, and contrast sensitivity tests, pupillometry, and the Hirschberg test by using screen 1 and providing the optical system 6 shown in FIG. 2 to the device.

[0031] The optical system 6 enables the observation of an image at infinity, thereby enabling the performance of tests other than perimetry as described above. The natural alignment of the eyeball and the observation from afar are ensured by the refractive adjustment made possible by the lens 7 and its movement along the optical axis of the system (see 8 in FIG. 2), and also by adjusting the distance between the optical means (lens or the display device itself further upstream) to match the interpupillary distance of the patient. Since the patient's eyes are positioned such that the optical axes are parallel and the eyes do not accommodate the object (displayed stimulus) and view it at infinity, the patient does not get overly tired during the examination, which is reflected in the results.

[0032] Figure 3 shows the positioning of the sample of the screen 1 and the optical system 6 inside the head 9 of the device according to the present invention. Another factor that enables this test, particularly the perimetry test, is the high contrast of the screen 1 by using the screen 1 together with two LCD panels 5a, 5b. The high contrast enables correct results to be maintained during the visual acuity test using the visual acuity chart and enables proper recognition of structures, such as a sine wave structure, while testing the contrast sensitivity. By using the additional optical system 6, spherical correction of refractive anomalies is possible by refractive adjustment in the range of, for example, -6D to 2D. This enables proper perimetry to be performed with respect to perimeters based on spherical and aspherical bowls, which is carried out with appropriate correction of the patient (mostly by applying a correction lens in front of the eye being tested). The said range of adjustment covers many of the population with refractive anomalies.

[0033] To perform complete dynamic perimetry, it is currently necessary for the device to be able to display stimuli in the full Goldmann range corresponding to generally accepted criteria for stimulus size and luminance. According to the subject matter of the present invention, using the screen 1 enables a wide dynamic range of 0 to 48 dB, a high dynamic resolution in the form of 65536 achieved luminance levels, and a maximum screen luminance of 10000 asb.

[0034] Due to its size, the present invention is a movable device that can stand independently or be attached to the head. Due to its mobility, the device can be used both in a hospital and in the home of a patient who has difficulty moving. The housing of the present invention (including the possibility of using a flexible gasket installed on the housing at a location where the patient brings their face close) and the installation method do not require further configuring the room to properly conduct the test because they block the patient's field of view from the surrounding situation (the test can be conducted in a room with the light switched on / the curtains of the window opened, or in extreme cases even outdoors). This mobility also enables examining the patient in a lying position if the patient cannot sit in front of the device.

[0035] The subject of the present invention can be manufactured as a device that enables operation in two modes: an upright mode as shown in FIG. 4 and a head-mounted mode as shown in FIG. 5. The upright mode, which can be used in a hospital, can be applied by positioning the head 9 of the device on a stand 10 that further enables adjusting the height of the head 9 and the chin rest 11. In this mode, the patient is steadily positioned relative to the screen 1 and the optical system 6, and the device does not impose a burden on the neck.

[0036] The mode can be switched by removing the head 9 from the stand 10 and fitting a head grip 12 (for example, in the form of a strip attached to the housing) to the device that enables firmly fixing the device to the head. In this mode, the patient can assume any position without the need to adjust the chin rest to the stand.

[0037] An embodiment of the screen 1 that guarantees a high dynamic range is shown in FIG. 1. The illumination layer 2 illuminates two modulation layers 5a, 5b in the form of an LCD panel to generate an image to be displayed to the patient.

[0038] The LCD panels 5a, 5b are positioned between three polarizing layers 4a, 4b, which are in the form of linear polarizers positioned relative to each other such that the polarizer 4b is in a cross - configuration with the polarizer 4a. For example, the polarizers 4a, 4b can be positioned relative to each other in the following order: a light - transmitting polarizer 4a having type s polarization, a light - transmitting polarizer 4b having type p polarization, and a light - transmitting polarizer 4a having type s polarization. The purpose of the first polarizer is to linearly polarize the non - polarized light coming from the illumination 2, and this light is then transmitted to the first LCD 5a. The degree of light passing through the LCD panel 5a depends on the orientation of the liquid crystal molecules within the display device.

[0039] In one state of the panel, the light polarization is changed by the liquid crystal cells of the LCD 5a such that the light passes through the polarizer 4b that is perpendicular to the first polarizer 4a and illuminates the pixels in the second LCD panel 5b.

[0040] In other states, the light is blocked by the type p polarizer 4b that is perpendicular to the type s polarizer 4a and thus does not reach the corresponding pixels in the next LCD panel 5b.

[0041] After passing through the type p polarizer 4b, the light that falls on the next LCD panel 5b illuminates the pixels corresponding to the pixels of the first LCD panel 5a with an appropriate brightness. Then, the light with appropriately changed polarization passes through the next type s polarizer 4a that is perpendicular to the type p polarizer 4b. In each of the polarizers 4a and 4b and the LCD panels 5a, 5b, the light is gradually attenuated until a high depth of black is achieved on the screen 1 at the spots where the pixels must be black.

[0042] Due to the loss of light intensity on the elements of the screen 1, a brightness enhancement element 3 is used that is positioned between the illumination layer 2 and the first type s polarizer 4a. This element makes it possible to achieve an appropriate brightness of the screen 1 for inspection, even up to 10000 asb.

[0043] The image displayed through Screen 1 is projected onto the patient's retina by an optical system 6 whose embodiment is shown in FIG. 2. The purpose of this system is to form a beam of light rays coming from Screen 1 so that the image is always produced on the fundus of the patient's eye. This is achieved by the movement 8 of the lens 7 along the optical axis of the system 6, for example, by refractive adjustment in the range of -6D to 2D.

[0044] In the following, a hierarchical scheme of the components of the device according to the invention is presented, showing one by one the effects achieved by specific groups of features indicated by the device.

[0045] In the simplest configuration, the device according to the invention suitable for and adjustable for eye examination requires the following components for operation: a housing, power supply means, a display unit, an optical system, and a cooling system. In this basic version, with respect to the components, it is very similar to other devices known in the prior art.

[0046] Due to the changes introduced as a result of long-term research and development, the device according to the invention is differentiated, specifically, - By using a display unit having the following structure, namely an illumination layer 2, a brightness enhancement layer 3, a first type of polarizing layer (polarizing plate) 4a, a first modulation layer (LCD panel) 5a, a second type of polarizing layer (polarizing plate) 4b, a second modulation layer (LCD panel) 5b, and a first type of polarizing layer (polarizing plate) 4a, a structure with energy consumption and heat generation that can ensure the level of brightness required for the examination, without damaging the components (without overheating the LCD panel) and can be cooled is formed. By using a system of two modulation layers (LCD panels) 5a, 5b that are monochrome, the possibility of using the discussed device is greatly limited, different from other already known display devices positioned near the user's eyes (for example, VR sets focus on the diversity of the displayed colors), but introduces significant advantages. This reduces energy consumption several times (and more than 10 times compared to similar devices with both color LCD panels tested during the development of this solution) compared to similar devices with at least one color LCD panel. As a result, instead of a large cooling system that is heavy and tires the user with the noise generated during operation, it is sufficient to use a smaller and user-friendly (lighter and quieter) cooling system.

[0047] The lighting layer 2, preferably in the form of an LED sheet, with a light-directing film, makes it possible to reduce the size of the display unit (compared to lighting with a single light source), and the energy consumption by the lighting layer 2 is reduced, reducing the amount of heat generated by it and also reducing the cooling requirement.

[0048] With the said modification, optimization of the cooling system is possible, where two-thirds or even three-quarters of the coolant is allocated to cool the LCD panel (the rest is allocated to cool the lighting layer 2).

[0049] Using the first type and the second type of polarizing layers (polarizing plates) 4a, 4b with a uniform light transmittance possible for the entire spectral range used (i.e., visible light) is a beneficial modification to address the problem of color change of the displayed image depending on the brightness of the screen 1. The uniform transmittance is defined as the lowest relationship of the transmittance coefficient to the light wavelength (i.e., preferably with a deviation of less than 10%). The said polarizing plate ensures a high brightness of the image while maintaining the lighting color over the range of brightness changes within which the screen 1 of the device according to the invention can operate.

[0050] Preferably, in some embodiments, by using one of the first type of polarizing plate 4a having a transmittance of about 50%, the luminance of the displayed image is increased. The other polarizing plates must exhibit a high absorption coefficient in order to achieve the minimum luminance required for the inspection.

[0051] The use of high-resolution LCD panels 5a, 5b provides for a free choice of tests. The larger number of pixels improves the measurement capabilities and accuracy (e.g., more possible areas / spots for illuminating while testing the field of view), and it becomes possible to meet the requirements of EN ISO 12866 related to the field of view test, specifically the stimulus size tolerance (+20% / -15% of the mentioned value, converted to solid angle). It is difficult to clearly specify a single exact and most beneficial resolution for the LCD panels 5a, 5b, because this is strictly dependent on the geometry of the device, particularly the distance between the screen 1 and the user's eye. Preferably, the value of the solid angle of the generated light stimulus should be 4.4 * 10 -5 steradians. If preferred guidelines expressed as values of solid angles are known, the LCD panel can be appropriately selected according to the specific geometry already given for the device.

[0052] The display unit, optical system, and cooling system, one for each eye, provide a great degree of freedom and independence in measurement, where in this case each eye can be inspected in a state adapted to the device without the user having to move away from the device and without having to switch the device from a left-eye measurement to a right-eye measurement, etc.

[0053] An axially movable correction lens provides for easy correction of the refractive abnormalities of the patient's eye, whereby the test can be carried out without having glasses, lenses in the cornea, etc.

[0054] With a deformable form having a movable display device, it is possible to correct the refractive abnormalities of the patient's eyes in the same way while reducing the weight and size of the device without using a lens.

[0055] Furthermore, the adjustable horizontal position of the display device / correction lens is beneficial because it allows the distance between these elements to be adjusted according to the patient's interpupillary distance.

[0056] By providing a grip 12 for attaching the device to the patient's head, the freedom of use of the device according to the present invention is greatly improved, especially for those who have difficulty or inconvenience sitting in front of a device placed on a table.

[0057] By providing a stand 10 and adjustment of the device housing according to two modes of measurement (with the device mounted on the head or on the table), the mobility and freedom of movement are greatly improved.

[0058] By providing two different power supply means (from the main power supply and the battery / accumulator), the mobility and freedom of movement of the device are further improved.

[0059] By providing a flexible gasket inside the housing to prevent light from outside the device from reaching the patient's eyes, the comfort of the measurement is improved, and this comfort is not disturbed by outside light or light coming from the monitor used by the person performing the test.

[0060] With a device capable of achieving a luminance of 10000 asb, it is possible to perform tests according to the generally accepted standards of visual field test devices.

[0061] With a device having its own computing system for controlling and performing eye examinations, the independence of the device and the possibility of using it as an automatic movable device for eye examinations are greatly improved.

[0062] Another beneficial and commonly encountered modification that can be included in the device according to the present invention is also the fact that it is provided with means for monitoring the movement of the eye's pupil, for example in the form of a camera that records the movement of the eye during an examination. Such an additional camera is beneficial because it enables tracking of the way the eye looks during the test, thereby providing the examiner with additional information about the state of the patient's eye.

[0063] The device according to the present invention can be configured to display light stimuli in various configurations, namely a single stimulus or multiple stimuli at once, according to the requirements, circumstances, and nature of the test.

[0064] It must be shown that the modifications discussed above can be used in various configurations.

Explanation of Reference Numerals

[0065] 1 Screen / display unit of the device according to the present invention 2 Lighting layer 3 Brightness enhancement layer 4a, 4b Polarizing layers of the first type and the second type 5a, 5b First and second modulation layers (for example, LCD panel) 6 Optical system 7 First lens from the optical system 8 Position adjustment direction of the first lens 9 Head of the device according to the present invention 10 Stand for the device according to the present invention 11 Chin rest 12 Adjustable head grip

Claims

1. 1. A visual inspection device comprising: a housing having a shape adapted to accommodate the head, and in particular the face, of a user for the duration of the test, including the other components of the device, in particular those described below; power supply means for supplying electrical energy to said device; a display unit (1) for generating light signals for carrying out the tests; an optical system (6) for transmitting the optical signal from the display unit to a patient; a dedicated cooling system for the display unit, The display unit comprises the following components arranged in the order given below: An illumination layer (2); At least one brightness enhancement layer (3), A first polarizing layer (4a); A first liquid crystal modulation layer (5a); A second polarizing layer (4b); and A second liquid crystal modulation layer (5b); A third polarizing layer (4a), A visual inspection device, characterised in that said first and second liquid crystal modulation layers (5a, 5b) are provided with monochrome LCD panels.

2. 2. The device according to claim 1, characterized in that the lighting layer (2) is selected from the group comprising LED sheets and CCFL panels connected to a light directing film.

3. 3. The device according to claim 2, characterized in that the first, second and third polarizing layers (4a, 4b, 4a) have a uniform transmittance within the spectral range of visible light, i.e. a transmittance deviation of less than 10%.

4. Both LCD panels (5a, 5b) are 4.4 ＊ 10 －５ 4. The device of claim 3, having an optical resolution suitable to achieve photostimulation over an area falling within a solid angle of a steradian +20% / -15%.

5. 5. A device according to claim 4, comprising two display units (1) as defined above, said optical system (6) and said dedicated cooling system, one for each eye.

6. 6. The device according to claim 4 or 5, wherein the optical system (6) is provided with a correction lens (7) respectively arranged for each eye, the correction lenses being positioned so as to be axially movable relative to the eye to be tested, independently of one another.

7. 6. The device according to claim 5, wherein both display units (1) are provided with means for moving each of said display units independently of each other with respect to the eye to be tested.

8. 8. The device according to claim 6 or 7, wherein the optical system (6) is provided with means for adjusting the position of the display unit (1) and / or the correction lens (7), for moving the display unit and / or the correction lens horizontally in order to adjust them to the interpupillary distance of the user.

9. 9. The device according to claim 8, wherein the dedicated cooling system is configured such that more than 50% of the cooling liquid used for cooling the display unit is used for cooling both LCD panels (5a, 5b), in particular more than 2 / 3 of the cooling liquid is used for cooling both LCD panels (5a, 5b), while the remainder of the cooling liquid is used for cooling the illumination layer (2).

10. 10. The device of claim 9, wherein the housing is provided with an adjustable grip (12) for attaching the device directly to the patient's head.

11. 11. The device according to claim 10, wherein the housing is additionally provided with connection means for mounting the device on a stand (10).

12. 12. A device according to claim 11, wherein the power supply means are provided with both an electrical connection for powering from a mains power supply and with a battery or accumulator directly connected to the device.

13. 13. The device of claim 11 or 12, wherein the housing has a replaceable, flexible gasket at a spot where the patient places their face to block light coming from outside the device during an examination.

14. 14. The device of claim 13 adapted and configured to achieve a luminance of 10000 asb +25% / -20%.

15. 15. The device of claim 14, comprising a digital computing system for controlling the operation of the device and for eye examination, the digital computing system being directly integrated into the device.

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