Apparatus for measuring objective refractive properties of eye

Abstract

A device (1) designed for measuring an objective refractive characteristic of an eye of a subject is provided, characterized in that the device (1) is designed for displaying a natural image (5) in a manner visible to the eye of the subject when measuring the objective refractive characteristic, wherein the amplitude (A) of the spatial frequency graph of the vertical direction of the image (5) is substantially inversely proportional to the spatial frequency (f) in a spatial frequency range of less than 50 cycles per degree.

Description

TECHNICAL FIELD

[0001] The present disclosure relates to a device for measuring objective refraction properties of an eye. The present disclosure relates to a computer program and a computer readable medium. BACKGROUND

[0002] In principle, the determination of subjective refraction properties differs from the measurement of objective refraction properties.

[0003] The goal followed for correcting refractive errors is to achieve the most (mathematically) positive correction value of the refractive error with the greatest visual acuity. Subjective assessment uses high-contrast optotypes, such as Landolt rings, numbers or letters, and is assessed at the threshold of visual acuity (the smallest still visible optotype). Unlike the subjective refraction measurement method, different content is used as the image of the focusing target when measuring objectively, for example using an (desk) autorefractor, for example a balloon image with a balloon as the focusing target.

[0004] WO 2017 / 050935 A1 relates to a system for determining subjective refraction properties of an eye of a subject different from the traditional prior art, wherein for this purpose a natural image is displayed to the subject on a display device and based on the feedback of the subject, various light refractive elements are arranged in the optical path between the eye of the subject and the display device displaying the image until the subject can clearly see the displayed image or a specific part thereof according to his subjective perception. Based on the characteristics of the light refractive elements, the subjective refraction properties of the eye of the subject are then determined at the point in time at which the subject can clearly see the displayed image according to his subjective perception. WO 2017 / 050935 A1 enriches the prior art for determining subjective refraction, in particular in that at least one natural image is used in the process of determining subjective refraction according to the teachings of WO 2017 / 050935 A1, instead of using vision characters or optotypes as traditionally predefined according to national and international standards. The inventors of WO 2017 / 050935 A1 have recognized that the way in which previous vision characters were presented does not necessarily lead to the best results when determining subjective refraction properties, since the traditional standardized conditions usually do not correspond to the conditions that the subject can encounter in everyday life.

[0005] The measurement of the objective refraction characteristic is significantly distinguished from the determination of the subjective refraction characteristic described above, since in the objective refraction measurement the refraction characteristic is actually measured by means of a device assembly (to be described in detail below) and with the aid of which the refraction characteristic of the eye to be examined is determined, whereas in the subjective refraction determination the refraction is not measured in the strict sense, but rather the subject is required to provide information about the perceived image sharpness for the determination of the subjective refraction measurement. That is, in the objective refraction measurement there is no communication with the subject and the challenge is to repeatedly or reliably place the eye to be examined in a state of minimum accommodation (to be described in detail below), in which the objective refraction characteristic can be reproducibly measured. In contrast, the placement of the subject in a certain mental state is irrelevant for the measurement of the objective refraction characteristic, for which the motivation for using natural images in WO 2017 / 050935 A1 is to determine the subjective refraction characteristic. Furthermore, the goal in terms of the state of minimum accommodation of the eye to be examined is opposite in the subjective and objective refraction measurement, since in the subjective refraction measurement the accommodation is suppressed by keeping the subject at a minimum distance of at least 4 m from the displayed image.

[0006] Therefore, the determination of the subjective refraction characteristic will not be discussed any further below, but rather the relevant measurement of the objective refraction characteristic is focused on here.

[0007] Devices for measuring the objective refraction characteristic of a subject's (optionally human) eye are generally known from the prior art. The device can be a refractometer, for example, in which a distinction is made here between a manual refractometer and an automatic refractometer, which are each exemplarily described in more detail below.

[0008] A manual refractometer projects a test image onto the retina of the subject's eye to be examined by means of a beam path, which can be observed by means of an observation beam path and can be focused by means of a manual change in the position of the test image relative to the eye, mostly by means of linear movement. The objective refraction characteristic corresponding to the manual change in position can be read, for example, by means of a scale in diopters (dpt), for example, in which a negative value indicates myopia and a positive value indicates hyperopia / farsightedness. In addition or alternatively, the measured value can also be output digitally and thus optionally digitized.

[0009] An automatic refractometer, also referred to as an autorefractometer, uses in most cases infrared light. The eye to be examined again fixates a test image and sends the test light onto the retina of the eye from an infrared light source arranged in combination with a raster diaphragm or a Schneidenblende. The test light is refracted from there back to the diaphragm position. A sensor, optionally a CCD camera, can detect a deviation of the reflected test light from the diaphragm position, which depends on the respective objective refraction properties of the eye to be examined of the subject. A data processing device, optionally a microcomputer, connected to the sensor can determine the objective refraction properties of the eye to be examined, i.e. the visual defect in dpt, based on the detected deviation.

[0010] In order to be able to see fixed or focal objects in space sharply depending on their distance, the curvature of the eye lens changes, which is generally referred to as accommodation. The accommodation thus generally refers to the dynamic adjustment of the refractive power of the eye and enables objects at any distance between the individual optical near point and far point of the eye to be examined to be imaged sharply on the retina plane and thus to meet the important prerequisite for sharp vision. The near point here denotes the shortest distance to the eye at which this state can be achieved, while the far point denotes the farthest distance. The change from far to near is referred to as near accommodation, while the accommodation from near to far is referred to as far accommodation. However, in a strict sense and in the present disclosure, the "accommodation" is understood exclusively or exclusively as near accommodation.

[0011] In both the above-mentioned devices or methods, the prerequisite for measuring the objective refraction properties of the eye is that the eye to be examined of the subject has been accommodated, i.e. no accommodation has taken place.

[0012] If the eye to be examined is accommodated, this can lead to a distortion of the measured values corresponding to the determined objective refraction properties of the eye to be examined, i.e. for example, to an erroneously more negative (myopic) measurement of the spherical component of the refractive error of the eye to be examined.

[0013] In order to avoid accommodation of the eye to be examined, it is conventional to use a test image with a focal object at a distance as the image. The focal object is in most cases a hot air balloon presented at a distance or a farmhouse presented at a distance, often in combination with a road leading to the focal object. The focal object is thus presented as a distant object or an object at a distance in the two-dimensional image. This is intended to ensure that the eye to be examined is in its most relaxed optical state when measuring the objective refraction properties of the eye to be examined, i.e. that the eye does not accommodate.

[0014] The disadvantage of these conventional presentations is that they sometimes lead to an undesired accommodation of the eye to be examined of the subject. Invention content

[0015] It can therefore be an object of the present disclosure to modify a device for measuring objective refraction properties in such a way that unwanted accommodation of the eye of the subject to be examined is avoided or at least reduced compared to the prior art described in the opening paragraph.

[0016] According to the present disclosure, this object is achieved by a device for measuring objective refraction properties of an eye according to the invention. Additionally or alternatively, according to the present disclosure, this object is also achieved by a computer readable medium according to the invention.

[0017] According to the present disclosure, this object is achieved by a device for measuring objective refraction properties of an eye, the device having:

[0018] - a storage device in which a natural image is stored as a focusing target for measuring objective refraction properties, wherein the amplitude of the spatial frequency profile in the vertical direction of the natural image is inversely proportional to the spatial frequency in a spatial frequency range of less than 50 cycles per degree for at least 80% of the spatial frequencies;

[0019] - a display device designed to display the natural image in a manner visible to the eye of a subject when measuring the objective refraction properties; and

[0020] - a processor designed to access the storage device and to operate the display device such that the display device displays the natural image in a manner visible to the eye of the subject to be examined when measuring the objective refraction properties.

[0021] The device is designed to display a natural image in a manner visible to the eye of a subject when measuring objective refraction properties. The amplitude of the spatial frequency profile in the vertical direction of the image is (at least) inversely proportional to the spatial frequency in a spatial frequency range of less than 50 cycles per degree for at least 80% of the spatial frequencies, optionally for at least 90% of the spatial frequencies, further optionally for at least 95% of the spatial frequencies. If two quantities are inversely proportional, one quantity increases and the other quantity decreases. In this regard, the term "inversely proportional" in the present invention refers in particular to the fact that the amplitude of the spatial frequency profile of the image can be represented by a substantially continuous curved curve.

[0022] That is, when measuring the objective refraction properties of a subject's, optionally a human's, eye, a natural image is displayed to the subject with the aid of the device, which is different from the conventionally used artificial image, such as the balloon image mentioned in the opening. The natural image is distinguished by the fact that the number curve of the spatial frequencies, i.e. the amplitude of the spatial frequency chart created for the vertical direction of the image, corresponds to the inverse of the spatial frequencies in the range of spatial frequencies of less than 50 cycles per degree for at least 80%, optionally for at least 90%, further optionally for at least 95% of the spatial frequencies. In other words, the amplitude of this spatial frequency chart can be described as a 1 / f curve at least in the range of spatial frequencies of less than 50 cycles per degree for at least 80%, optionally for at least 90%, further optionally for at least 95% of the spatial frequencies, wherein f corresponds to the spatial frequency in cycles per degree.

[0023] The amplitude of the spatial frequency chart of the vertical direction of the image can always be inversely proportional to the spatial frequencies at least in the range of spatial frequencies of 1 or 2 to 5 cycles per degree, optionally 1 or 2 to 7 cycles per degree, further optionally 1 to 10 cycles per degree, further optionally in the range of spatial frequencies of less than 50 cycles per degree. The amplitude of the spatial frequency chart of the vertical direction of the image can preferably be inversely proportional to the spatial frequencies at least in the range of spatial frequencies of 2 to 5 cycles per degree. Here, the range of spatial frequencies is thus not limited to 2 (inclusive) to 5 (inclusive) cycles per degree, but can further extend, for example, from 1 to 10 cycles per degree. It is thus also conceivable that the amplitude of the spatial frequency chart of the vertical direction of the image is always inversely proportional to the spatial frequencies.

[0024] The at least above given amplitude curve of the spatial frequency chart of the vertical direction of the image distinguishes the image according to the present disclosure from conventionally used artificial images, which have an amplitude of the spatial frequency chart that is different from the 1 / f curve in the range of spatial frequencies of less than 50 cycles per degree for more than 20% of the spatial frequencies. This applies in particular to the range of spatial frequencies of 2 to 5 cycles per degree, optionally 1 to 10 or more cycles per degree. More precisely, it is possible to observe an amplitude curve of the spatial frequency chart of the vertical direction of the artificial image in the case of conventionally used artificial images, which is initially almost constant in this range, while it falls with a very steep slope at the end of the range. That is, in this range, the amplitude of the spatial frequencies is smaller in the case of the natural image according to the present disclosure than in the case of the conventional artificial image, or in other words, the number of spatial frequencies is smaller in the case of the natural image according to the present disclosure than in the case of the conventional artificial image.

[0025] Here, the device is not limited to monocular measurement of the objective refraction properties, but can also be a device that is designed to perform the measurement of the objective refraction properties for both eyes or both eyes simultaneously.

[0026] It has been recognised in accordance with the present disclosure that when using images as the focus target to measure objective refractive properties, their spatial frequency content and distribution have a large impact on the accommodative response of the eye under examination. Evidence has been found in the literature that the accommodative response is affected by the spatial frequency quantity distribution.Initially, the literature assumed that spatial frequencies above 10 cycles per degree (cpd) were required for the most accurate possible response of the accommodation system (Charman WN, Tucker J. Dependence of accommodation response on the spatial frequency spectrum of the observed object. Vision Res. 1977;17(1): 129-39. doi: 10.1016 / 0042-6989(77)90211-5.PMID: 855197.[Accommodation response dependence on the spatial frequency spectrum of the observed object, Vision Research, 1977, 17(1):129-39. doi:10.1016 / 0042-6989(77)90211-5,PMID:855197.]). However, recent research indicates that high spatial frequencies lead to unstable accommodation system responses, while spatial frequencies in the intermediate range (approximately 2 to 7 cpd) are more important (Strang NC, DayM, Gray). LS & Seidel D. Accommodation steps, target spatial frequency and refractive error. Ophthalmic Physiol Opt 2011, 31, 444-455. doi:10.1111 / j.1475-1313.2011.00855.x [Adjustment of step size, target spatial frequency and refractive error, Ophthalmology & Optics, 2011, 31, pp. 444-455, doi:0.1111 / j.1475-1313.2011.00855.x] and Sanz Diez P, Schaeffel F, Wahl S, Ohlendorf A. Accommodation responses following contrast adaptation. Vision Res. 2020 May; 170:12-17. doi: 10.1016 / j.visres.2020.03.003. Epub 2020 Mar 24. PMID: 32217367. [Accommodative response after contrast adaptation, Visual Research, May 2020, 170:12-17, doi:10.1016 / Journal of Visual Research, 2020.03.003, Epub March 4, 2020, PMID:32217367.]). It has been recognized in this disclosure that the spatial frequency content of the image has a significant influence on the accommodation of the eye being examined when measuring objective refractive characteristics.When the spatial frequency distribution of an image, especially in the lower spatial frequency range (optionally 1 to 10 cpd, further optionally 1 to 7 cpd, even optionally 2 to 7 cpd, and even optionally 1 or 2 to 5 cpd), does not follow a 1 / f function, accommodation can be negatively affected by these images. In measuring objective refractive errors, this can lead to more negative measurements, particularly of the spherical portion of the refractive error. It has also been recognized according to this disclosure that natural images have precisely a 1 / f distribution of the amplitude of the spatial frequency, thereby eliciting the desired accommodative response from the eye being examined by using natural images, which in turn produces more accurate or precise measurements.

[0027] Therefore, using natural images provides the following technical effect: compared to artificial images, the subject's eye is less inclined to adjust when objective refractive characteristics are measured in the presence of natural images, which in turn leads to improved and higher quality measurement results.

[0028] Therefore, starting from the prior art described at the beginning, namely, using devices that employ artificial images to measure objective refractive properties, the objective technical task facing those skilled in the art is to modify these devices or apparatuses to avoid or at least reduce unwanted accommodation of the subject's eye relative to the prior art described at the beginning.

[0029] As explained above, images with different contents are used as the focusing target when measuring objective refractive properties, for example, using a (desktop) automated refractometer. When using such a target in conjunction with an automated refractometer, it is essential to ensure that this objective measurement of refractive error does not result in a (mathematically) negative value for the refractive error, particularly the spherical component. One of the main factors affecting the results of objective refractive property measurements is the change in the curvature of the eye's lens during target observation, a process known as accommodation and accompanied by changes in the eye's refractive power (see also above).

[0030] Since the prior art related to the measurement of objective refractive properties does not provide any basis for those skilled in the art to solve objective technical problems by displaying natural images, the solutions according to this disclosure are based on inventive activities.

[0031] Objective refractive characteristics may involve the spherical portion of refractive power (i.e., myopia, hyperopia, and / or emmetropia), astigmatism and its axial position, and / or low-order and / or high-order imaging errors, described, for example, by so-called Zernike polynomials. Depending on the design of the device, objective refractive characteristics may be determined, for example, as "intraocular" imaging errors (i.e., as the total result) and / or corneal and lens errors (i.e., each as a partial error, which can partially cancel each other out or enhance each other and together constitute the entire wavefront).

[0032] The optional improvements to the device will be described in detail below.

[0033] In other words, as already shown above, the spatial frequency range in which the amplitude of the spatial frequency graph in the vertical direction of the image can be described as a 1 / f curve is not limited to a certain range, but can span all spatial frequencies corresponding to the reciprocal of the spatial frequency. This can further enhance the aforementioned technical effect of reducing accommodation when performing objective refractive characteristic measurements.

[0034] It is conceivable that the amplitude of the horizontal spatial frequency chart of the image is (at least) inversely proportional to the spatial frequency in a spatial frequency range of less than 50 cycles per degree for at least 80% of the spatial frequency, optionally at least 90% of the spatial frequency, and further optionally at least 95% of the spatial frequency. It is also conceivable that the amplitude (A) of the horizontal spatial frequency chart of the image is at least in a spatial frequency range of 1 or 2 to 5 cycles per degree, optionally 1 or 2 to 7 cycles per degree, and further optionally 1 to 10 cycles per degree, and further optionally always inversely proportional to the spatial frequency. The amplitude of the vertical spatial frequency chart of the image is preferably inversely proportional to the spatial frequency in a spatial frequency range of at least 2 to 5 cycles per degree.

[0035] The above description regarding the spatial frequency chart of the image in the vertical direction also applies, wherein when measuring objective refractive characteristics, the amplitude curve of the spatial frequency chart of the image in the horizontal direction can be used to further enhance the above-mentioned effect of reducing accommodation.

[0036] It is conceivable that the device is a refractometer, optionally a manual refractometer or an automatic refractometer.

[0037] For a definition or description of a refractometer, please refer to the paragraph above. The combination of natural images and a refractometer, among other things, provides the following technical effects: by reducing accommodation achieved with the aid of natural images, the measurement of objective refractive properties using a refractometer can be further simplified and its measurement quality improved. In other words, refractometers generally have the advantage of being easy to operate, even by inexperienced personnel, because they do not require interaction with the subject compared to the determination of subjective refractive properties as described at the outset. However, because no interaction is required, unwanted accommodation by the subject may be partially undetectable or undetermined within the scope of objective refractive power measurements using a refractometer; therefore, even if accommodation occurs unexpectedly in an objective refractive power measurement, the result is still considered valid. Using natural images in conjunction with a refractometer can reduce the number of measurements obtained with a refractometer that record unidentified accommodation by reliably suppressing or avoiding accommodation itself. Objective refractive power measurements using a refractometer are therefore more reliable.

[0038] Imagine that the image has a target area for the subject's eye to focus on, wherein the chromaticity of the target area is greater than that of the area surrounding the target area.

[0039] In other words, the target area that the subject should focus on during measurement can be brighter than the area surrounding the target area. This makes the natural image different from the conventional balloon image, where the target area formed by the balloon is darker than the area around it. In this case, the area surrounding the target area is usually larger than the target area itself, so the total brightness of the image is primarily determined by the area surrounding the target area. This total brightness of the image, in turn, depends on the pupil size of the subject's eyes, especially when measuring objective refractive properties, where the pupil size should be as large as possible. Furthermore, because the target area is brighter, the subject can identify the target area at least as well, or even better, thus avoiding undesirable accommodation. Therefore, in addition to enhancing the suppression of accommodation, the overall brightness of the image can be reduced by the darker surrounding area compared to the target area, and thus the pupil size can be enlarged when measuring objective refractive properties, leading to better measurement results of objective refractive properties.

[0040] It is conceivable that the area surrounding the target area would be at least partially covered in black.

[0041] This enhances the aforementioned advantages of the relative brightness between the target area and its surrounding area, as the contrast between the target area and its surrounding area becomes maximum. Therefore, the target area can be well identified by the subject or separated from its surrounding areas, thus avoiding undesirable accommodation. Furthermore, selecting black minimizes the overall brightness of the image, thereby maximizing pupil size when measuring objective refractive properties, which in turn leads to better measurement results of objective refractive properties (see above).

[0042] It is conceivable that the area surrounding the target region covers at least the upper half of the image.

[0043] This allows for the darker application of larger areas of the image, which in turn keeps the overall brightness of the image low. This allows for the maximum expansion of the pupil size when measuring objective refractive properties, resulting in better measurement results of objective refractive properties (see above).

[0044] It is conceivable that objects presented at a distance are arranged in or form a target area as a focusing target for the subject's eye to focus.

[0045] An object presented at a distance can be understood as the object that appears furthest to the subject compared to the rest of the objects presented in the image. In two-dimensional imaging, i.e., in the case of an image, spatial attribution must be reconstructed from the objects being imaged. Here, spatial effects can be generated through visual cues, allowing objects to appear near or far relative to each other for the observer. For this purpose, linear perspective, relative size of objects, occlusion or scene effects, shadows, aerial perspective, relative height of objects, and / or motion parallax can be utilized. Undesirable (near) accommodation is suppressed by presenting the focal target at a distance.

[0046] The image may have a third region arranged below the region surrounding the target region, the chromaticity and brightness of which are greater than those of the region surrounding the target region.

[0047] In other words, the image can be broadly divided into three regions, which are distinguished from each other by their respective brightness. Here, the region referred to above as the third region can be presented at the bottom of the image, with the region surrounding the target region connecting to or adjacent to it from above. The lower region thus forms a horizontal line that serves as a boundary with the region surrounding the target region. In two-dimensional imaging, that is, in this image, objects near the horizontal line are interpreted as being farther away than those seen above or below them. The target region can be centered in the image and thus close to the horizontal line formed by the third region or the lower region, so that the subject perceives the target region as a distant object. This, in turn, prevents (near) accommodation when the subject focuses on the target region or the target object. For example, this is suitable for presenting a photograph of sunrise or, in particular, an image of the so-called Earth rising as seen from the Moon. The advantage, especially in the latter case, is that the region surrounding the Earth, which serves as the target object for focusing, is black, and therefore very dark (see also the description of its advantages above).

[0048] Conversely, the device may include: a storage device storing images; a display device configured to display the images in a manner visible to the subject's eye during the measurement of objective refractive characteristics; and a processor configured to access the storage device and manipulate the display device such that it displays the images in a manner visible to the subject's eye during the measurement of objective refractive characteristics. These components may be parts of the aforementioned refractometer or mounted in a conventional refractometer. This provides the advantage that the solution according to this disclosure can be used in combination with a conventional refractometer.

[0049] Furthermore, this disclosure also relates to a computer program for an apparatus designed for measuring the objective refractive properties of a subject's eye, wherein the apparatus is designed to display a natural image in a manner visible to the subject's eye during the measurement of objective refractive properties, wherein the amplitude of the spatial frequency chart in the vertical direction of the image is inversely proportional to the spatial frequency (f) in a spatial frequency range of less than 50 cycles per degree for at least 80% of the spatial frequency, optionally at least 90% of the spatial frequency, and further optionally at least 95% of the spatial frequency. The amplitude of the spatial frequency chart in the vertical direction of the image may always be inversely proportional to the spatial frequency in a spatial frequency range of at least 1 or 2 to 5 cycles per degree, optionally 1 or 2 to 7 cycles per degree, further optionally 1 to 10 cycles per degree, and further optionally less than 50 cycles per degree. Preferably, the amplitude of the spatial frequency chart in the vertical direction of the image may be inversely proportional to the spatial frequency in a spatial frequency range of at least 2 to 5 cycles per degree.

[0050] The computer program includes commands that, when executed through the device, cause the device to display an image in a manner visible to the subject's eye during the measurement of objective refractive properties.

[0051] The device can be the one described above.

[0052] The program code of this computer program can exist in any code form, especially in the code form applicable to the refractometer controller.

[0053] The above description of the device also applies to the computer program, and vice versa.

[0054] Furthermore, this disclosure also relates to a computer-readable medium for an apparatus designed for measuring the objective refractive properties of a subject's eye, wherein the apparatus is designed to display a natural image in a manner visible to the subject's eye during the measurement of objective refractive properties, wherein the amplitude of the spatial frequency chart in the vertical direction of the image is inversely proportional to the spatial frequency (f) in a spatial frequency range of less than 50 cycles per degree with respect to at least 80% of the spatial frequency, optionally at least 90% of the spatial frequency, and further optionally at least 95% of the spatial frequency. The amplitude of the spatial frequency chart in the vertical direction of the image may be inversely proportional to the spatial frequency in a spatial frequency range of at least 1 or 2 to 5 cycles per degree, optionally 1 or 2 to 7 cycles per degree, further optionally 1 to 10 cycles per degree, and further optionally always inversely proportional to the spatial frequency in a spatial frequency range of less than 50 cycles per degree. Preferably, the amplitude of the spatial frequency chart in the vertical direction of the image may be inversely proportional to the spatial frequency in a spatial frequency range of at least 2 to 5 cycles per degree.

[0055] The computer-readable medium includes commands that, when executed by the device, cause the device to display an image in a manner visible to the subject's eye when measuring objective refractive properties.

[0056] In other words, a computer-readable medium may be provided that includes the computer program defined above.

[0057] The computer-readable medium can be any digital data storage device, such as a USB memory, hard disk, CD-ROM, SD card, or SSD card.

[0058] The computer program does not necessarily have to be stored on such a computer-readable storage medium for use by the device, but can also be obtained from the outside via the Internet or other means.

[0059] In other words, the computer-readable medium can be a data signal for a device designed to measure the objective refractive characteristics of a subject's eye, wherein the device is designed to display a natural image in a manner visible to the subject's eye when measuring the objective refractive characteristics, wherein the amplitude of the vertical spatial frequency chart of the image is inversely proportional to the spatial frequency (f) in a spatial frequency range of less than 50 cycles per degree with respect to at least 80% of the spatial frequency, optionally at least 90% of the spatial frequency, and further optionally at least 95% of the spatial frequency. The amplitude of the vertical spatial frequency chart of the image can be inversely proportional to the spatial frequency in a spatial frequency range of at least 1 or 2 to 5 cycles per degree, optionally 1 or 2 to 7 cycles per degree, further optionally 1 to 10 cycles per degree, and further optionally always inversely proportional to the spatial frequency in a spatial frequency range of less than 50 cycles per degree. Preferably, the amplitude of the vertical spatial frequency chart of the image can be inversely proportional to the spatial frequency in a spatial frequency range of at least 2 to 5 cycles per degree.

[0060] The data signal includes commands that, when executed by the device, cause the device to display an image in a manner visible to the subject's eye when measuring objective refractive properties.

[0061] The device can be the one described above.

[0062] The foregoing description of the device and the computer program also applies to the computer-readable medium, and vice versa.

[0063] Additionally or alternatively, this disclosure may also relate to the use of natural images for measuring the objective refractive properties of a subject's eye, wherein the image is displayed in a manner visible to the subject's eye when measuring the objective refractive properties, and wherein the amplitude of the spatial frequency chart in the vertical direction of the image is inversely proportional to the spatial frequency (f) in a spatial frequency range of less than 50 cycles per degree with respect to at least 80% of the spatial frequency, optionally at least 90% of the spatial frequency, and further optionally at least 95% of the spatial frequency. The amplitude of the spatial frequency chart in the vertical direction of the image may be inversely proportional to the spatial frequency in a spatial frequency range of at least 1 or 2 to 5 cycles per degree, optionally 1 or 2 to 7 cycles per degree, further optionally 1 to 10 cycles per degree, and further optionally always inversely proportional to the spatial frequency in a spatial frequency range of less than 50 cycles per degree. Preferably, the amplitude of the spatial frequency chart in the vertical direction of the image may be inversely proportional to the spatial frequency in a spatial frequency range of at least 2 to 5 cycles per degree.

[0064] The foregoing description of the device, the computer program, and the computer-readable medium also applies to this purpose, and vice versa.

[0065] Additionally or alternatively, this disclosure may also relate to a method for controlling a device designed for measuring the objective refractive properties of a subject's eye, wherein the method includes manipulating the device to display a natural image visible to the subject's eye during the measurement of the objective refractive properties of the subject's eye, wherein the amplitude of the spatial frequency chart in the vertical direction of the image is inversely proportional to the spatial frequency (f) in a spatial frequency range of less than 50 cycles per degree with respect to at least 80% of the spatial frequency, optionally at least 90% of the spatial frequency, and further optionally at least 95% of the spatial frequency. The amplitude of the spatial frequency chart in the vertical direction of the image may be inversely proportional to the spatial frequency in a spatial frequency range of at least 1 or 2 to 5 cycles per degree, optionally 1 or 2 to 7 cycles per degree, further optionally 1 to 10 cycles per degree, and further optionally always inversely proportional to the spatial frequency in a spatial frequency range of less than 50 cycles per degree. Preferably, the amplitude of the spatial frequency chart in the vertical direction of the image may be inversely proportional to the spatial frequency in a spatial frequency range of at least 2 to 5 cycles per degree. This method can be a computer-implemented method, meaning that one, more, or all of the steps of the method can be implemented at least in part by a device or computer for data processing.

[0066] The foregoing description of the device, the computer program, the computer-readable medium, and the purpose also applies to the control method, and vice versa. Attached Figure Description

[0067] The following reference Figures 1 to 6To describe possible implementations of this disclosure.

[0068] Figure 1 A device designed to measure the objective refractive properties of a subject's eye is shown schematically.

[0069] Figure 2 schematically illustrates the conventional method. Figure 1 The device uses artificial images.

[0070] Figure 3 schematically illustrates the spatial frequency graph of the image in the vertical direction from the artificial image in Figure 2.

[0071] Figure 4 Schematic illustration of the invention as provided in this disclosure Figure 1 The device uses natural images.

[0072] Figure 5 Schematic illustration of from Figure 4 The spatial frequency chart of the vertical direction of the natural image, and

[0073] Figure 6 Schematic illustration of from Figure 4 The spatial frequency chart of the horizontal direction of the natural image. Detailed Implementation

[0074] exist Figure 1 The image shows a device 1, such as a refractometer, optionally a manual refractometer or a (desktop) automatic refractometer, which is designed to measure the objective refractive properties of a subject's (not shown) eye.

[0075] Device 1 includes: a storage device 3 in which natural images 5 are stored (see...) Figure 4 ( ); display device 2, which is designed to display a natural image stored in storage device 3 in a manner visible to the subject's eye during the measurement of objective refractive characteristics; and processor 4, which is designed to access storage device 3 and manipulate display device 2 such that display device 2 displays the image in a manner visible to the subject's eye during the measurement of objective refractive characteristics.

[0076] The following is a detailed description. Figure 4 The natural image 5 used according to this disclosure is shown in Figure 5, and the conventionally used artificial image 6 is shown in Figure 2. Both images 5 and 6 are color images here, with the natural image 5 corresponding to a photograph.

[0077] The conventional image 6 (see Figure 2) is a so-called balloon image, in which the apparatus 1 uses a balloon 61 as a focusing target or object during objective refractive measurement. Here, the balloon 61 that forms the target region 62 for focusing is surrounded by a region 63, which has a greater chromaticity brightness than the balloon 61 that forms the target region 62.

[0078] In contrast, in natural image 5 (see Figure 4 In this image, the so-called Earth-rising image is a photograph taken from the Moon 54 toward the Earth 51, where the Earth 51 forms a target area 52 for focusing the eye being examined during objective refractive power measurements using the apparatus 1. Here, the Earth 51 forming the target area 52 has a higher or greater chromaticity than the surrounding black area 53. The area 53 surrounding the target area 52 covers slightly more than the upper half of the natural image 5. Adjacent to the area 53 surrounding the target area 52 below is a third area 55 formed by the Moon or lunar surface 54, in such a way that a generally horizontal boundary 56 between the third area 55 and the area 53 surrounding the target area 52 forms a horizontal line. Since the target area 52 formed by the Earth 51 is completely surrounded by the black area 53, the Earth 51 is vertically separated from the horizontal line or boundary 56, which, in addition to the shadows cast on the Earth 51, also facilitates the use of the Earth 51 as a distant object as a focusing target for focusing the subject's eye during objective refractive power measurements using the apparatus 1. This prevents near accommodation in the eye being examined. Furthermore, compared to the total chromaticity of the artificial image 6, the black region 53 reduces the total chromaticity of the natural image 5, causing a relative increase in pupil size in the subject's eye being examined. Further contributing to this is that, while the chromaticity of the third region 55 formed by the moon 54 is greater than that of the region 53 surrounding the target region 52, it is still less than the chromaticity of the corresponding lower region 64 of the artificial image 6 (see also Figure 2).

[0079] In addition, refer to Figure 3, Figure 5 and Figure 6 The spatial frequency chart shown in Figure 3 corresponds to the conventional image 6 in Figure 2. Figure 5 and Figure 6 The two spatial frequency charts in the diagram correspond to natural image 5 according to this disclosure.

[0080] More precisely, in a spatial frequency chart, the spatial frequency f is displayed on the corresponding horizontal axis within the range of 0 to 50 cycles per degree (cpd). The amplitude or quantity A of the spatial frequency is plotted on the corresponding vertical axis of the spatial frequency chart. The spatial frequency chart shown in Figure 3 was created for the vertical direction of the artificial image 6, while...Figure 5 The spatial frequency chart shown is created for the vertical direction of natural image 5. Figure 6 The spatial frequency chart shown is created for the horizontal direction of natural image 5.

[0081] As from Figure 5 and Figure 6 The result shows that the amplitude A of the spatial frequency charts in both the horizontal and vertical directions of the natural image 5 is consistently inversely proportional to the spatial frequency f, i.e., A = 1 / f, in the range of 0 cpd to 50 cpd. This corresponds to 100% of the spatial frequency within this range. However, distributions greater than or equal to 80%, 90%, or 95% are conceivable. In contrast, the amplitude A of the spatial frequency chart of the artificial image 6 shown in Figure 3 deviates from the 1 / f curve at least in the range of 1 cpd to 10 cpd, and especially in the range of 1 cpd to 5 cpd, and is therefore distinct from... Figure 5 The spatial frequency chart corresponding to the natural image 5 shown in the image is presented.

[0082] This makes it consistent with A = 1 / f within the above range (see...). Figure 5 Compared to the natural image 5 (within the circled area), the artificial image 6 has a larger number of spatial frequencies in the range of 1 cpd to 10 cpd, especially 1 cpd to 7 cpd, and even more particularly in the range of 1 cpd to 5 cpd. Therefore, when measuring objective refractive properties, the natural image 5 better suppresses or avoids accommodation compared to the artificial image 6, as explained in detail above.

[0083] List of reference numerals

[0084] 1. A device designed to measure the objective refractive properties of a subject's eye.

[0085] 2 Display device

[0086] 3. Storage device

[0087] 4 processors

[0088] 5 Natural Images

[0089] 51 Earth

[0090] 52 Target Area

[0091] 53. The area surrounding the target area

[0092] 54. The Moon or its surface

[0093] 55 Third or lower area

[0094] 56. Horizontal line or boundary line

[0095] 6. Artificial Images

[0096] 61 balloons

[0097] 62 Target Area

[0098] 63. The area surrounding the target area

[0099] 64 Lower region

[0100] A. Amplitude of spatial frequency

[0101] f Spatial frequency

Claims

1. A device (1) for measuring objective refractive properties of an eye, characterized in that, The device (1) has: - a storage device (3) in which a natural image (5) is stored as a focusing target for measuring an objective refraction property, wherein the amplitude (A) of the spatial frequency profile in the vertical direction of the natural image (5) is inversely proportional to the spatial frequency (f) in a spatial frequency range of less than 50 cycles per degree for at least 80% of the spatial frequencies; - a display device (2) designed to display the natural image (5) in a manner visible to the subject's eye when measuring the objective refraction property; and - a processor (4) designed to access the storage device (3) and to operate the display device (2) such that the display device (2) displays the natural image (5) in a manner visible to the subject's eye to be examined when measuring the objective refraction property.

2. The device (1) for measuring objective refractive properties of an eye according to claim 1, characterized in that, The amplitude (A) of the spatial frequency profile in the vertical direction of the natural image (5) is inversely proportional to the spatial frequency (f) in a spatial frequency range of less than 50 cycles per degree for at least 90% of the spatial frequencies.

3. The device (1) for measuring objective refractive properties of an eye according to claim 1, characterized in that, The amplitude (A) of the spatial frequency profile in the vertical direction of the natural image (5) is inversely proportional to the spatial frequency (f) in a spatial frequency range of less than 50 cycles per degree for at least 95% of the spatial frequencies.

4. The device (1) for measuring objective refractive properties of an eye according to claim 1, characterized in that, The amplitude (A) of the spatial frequency profile in the vertical direction of the image (5) is always inversely proportional to the spatial frequency (f) at least in a spatial frequency range of 1 or 2 to 5 cycles per degree.

5. The apparatus (1) for measuring objective refractive properties of an eye according to claim 4, characterized in that, The amplitude (A) of the spatial frequency profile in the vertical direction of the image (5) is always inversely proportional to the spatial frequency (f) at least in a spatial frequency range of 1 or 2 to 7 cycles per degree.

6. The device (1) for measuring objective refractive properties of an eye according to claim 4, characterized in that, The amplitude (A) of the spatial frequency profile in the vertical direction of the image (5) is always inversely proportional to the spatial frequency (f) at least in a spatial frequency range of 1 to 10 cycles per degree.

7. The device (1) for measuring objective refractive properties of an eye according to claim 4, characterized in that, The amplitude (A) of the spatial frequency profile in the vertical direction of the image (5) is always inversely proportional to the spatial frequency (f) at least in a spatial frequency range of less than 50 cycles per degree.

8. Device (1) for measuring objective refractive properties of an eye according to claim 1 or 4, characterized in that, The amplitude (A) of the spatial frequency profile in the horizontal direction of the image (5) is inversely proportional to the spatial frequency (f) at least in a spatial frequency range of less than 50 cycles per degree for at least 80% of the spatial frequencies.

9. The apparatus (1) for measuring objective refractive properties of an eye according to claim 8, characterized in that, The amplitude (A) of the spatial frequency profile in the horizontal direction of the image (5) is inversely proportional to the spatial frequency (f) at least in a spatial frequency range of less than 50 cycles per degree for at least 90% of the spatial frequencies.

10. The device (1) for measuring objective refractive properties of an eye according to claim 8, characterized in that, The amplitude (A) of the spatial frequency profile in the horizontal direction of the image (5) is inversely proportional to the spatial frequency (f) at least in a spatial frequency range of less than 50 cycles per degree for at least 95% of the spatial frequencies.

11. The device (1) for measuring objective refractive properties of an eye according to claim 8, characterized in that, The amplitude (A) of the spatial frequency profile in the horizontal direction of the image (5) is always inversely proportional to the spatial frequency (f) at least in a spatial frequency range of 1 or 2 to 5 cycles per degree.

12. The device (1) for measuring objective refractive properties of an eye according to claim 8, characterized in that, The amplitude (A) of the spatial frequency diagram of the image (5) in the horizontal direction is always inversely proportional to the spatial frequency (f) at least in the range of 1 or 2 to 7 cycles per degree.

13. The device (1) for measuring objective refractive properties of an eye according to claim 8, characterized in that, The amplitude (A) of the spatial frequency diagram of the image (5) in the horizontal direction is always inversely proportional to the spatial frequency (f) at least in the range of 1 to 10 cycles per degree.

14. The device (1) for measuring objective refractive properties of an eye according to claim 8, characterized in that, The amplitude (A) of the spatial frequency diagram of the image (5) in the horizontal direction is always inversely proportional to the spatial frequency (f) at least in the range of less than 50 cycles per degree.

15. The device (1) for measuring objective refractive properties of an eye according to claim 1 or 4, characterized in that, The device (1) is a refractometer.

16. The device (1) according to claim 15, characterized in that The device (1) is a manual refractometer or an automatic refractometer.

17. A device (1) for measuring objective refractive properties of an eye according to claim 1 or 4, characterized in that, The image (5) has a target region (52) for focusing the eye of the subject, wherein the chromatic brightness in the target region (52) is greater than the chromatic brightness in a region (53) surrounding the target region (52).

18. The apparatus (1) for measuring objective refractive properties of an eye according to claim 17, characterized in that The region (53) surrounding the target region (52) is at least partially implemented in black.

19. The apparatus (1) for measuring objective refractive properties of an eye according to claim 17, characterized in that, The region (53) surrounding the target region (52) covers at least the upper half of the image (5).

20. The apparatus (1) for measuring objective refractive properties of an eye according to claim 17, characterized in that, An object (51) appearing at a distance is arranged in the target region (52) or forms the target region as a focusing target for focusing the eye of the subject.

21. The apparatus (1) for measuring objective refractive properties of an eye according to claim 17, characterized in that, The image (5) has a third region (55) arranged below the region (53) surrounding the target region (52), the chromatic brightness of which is greater than the chromatic brightness of the region (53) surrounding the target region (52).

Images