Method for testing eyes and vision testing system

Abstract

The invention relates to a method for testing an eye of a subject by means of a vision testing system (10), comprising a first measuring device (11), a second topographic measuring device (12), a third refractive measuring device (13) and a processing device (14), wherein the central axial length (L) of the eye (16) of the subject is measured by means of the first measuring device. Z ) and peripheral axial length (L P ), measuring the curvature of the cornea (35) of the eye by means of a second measuring device, measuring the refractive properties of the eye by means of a third measuring device, processing the measurement data of the measurements of the first measuring device, the second measuring device and the third measuring device by means of a processing device, and the processing device outputting the measurement data.

Description

[0001] The present invention relates to a method for testing a subject's eye having the features of an embodiment of the present disclosure and a vision testing system having the features of a preferred embodiment of the present disclosure.

[0002] Refractive measurement devices are well known and are routinely used to determine the refractive value of a subject's eye. The refractive value can be used to assess the optical refractive error of the eye. A common form of refractive error is myopia, in which the focal plane is in front of the retina, which results in blurred visual perception. Different forms of myopia are distinguished. In the case of so-called axial myopia, the axial length of the eye increases. In the case of refractive myopia, the refractive power of the refractive parts of the eye, such as the cornea or lens, increases. The increase in refractive power may, for example, be caused by an increase in the curvature of the refractive surface (e.g., the cornea). It may also be caused by a change in the refractive index of the lens, resulting in an increase in refractive power. Myopia may have developed during childhood due to various environmental factors (e.g., visual tasks in the close range of the eye), or it may develop with age, for example, due to a decrease in the accommodative ability of the ciliary muscle and the lens. In addition to medication intake, diseases (e.g., diabetes) or genetic characteristics may also be causes of myopia.

[0003] With the aid of a refractometer, the refractive value can be determined objectively in diopters (dpt) relatively easily. For example, DE 102 006 017 389 A1 discloses a vision testing system consisting of a refractometer and a topography measuring device. In this case, the refractometer is an automatic refractometer combined with a topography measuring device implemented as a keratometer. The keratometer can be used to determine the topography of the cornea, which allows information to be obtained about possible causes of myopia, such as a suspected cataract.

[0004] However, the evaluation of refractive and topographic data obtained in this way is difficult, as refractive measurements can be inaccurate and other influencing factors can also lead to distorted refractive values. For example, inaccurate refractive measurements can occur when the subject's eye accommodates at close range during the measurement. To prevent this, medications can be used to paralyze the ciliary muscle (cycloplegia), which is however time-consuming and unpleasant for the subject.

[0005] In the case of axial myopia, the central axial length of the eye increases, which also causes the wall structures of the eye (especially the retina) to be stretched. This stretching then also affects the peripheral (equatorial) retina. In the area of the peripheral retina, the peripheral refractive values may therefore differ from the central refractive values measured in the center of the visual axis. If axial myopia is corrected with the help of frame glasses or contact lenses, the focal plane or focus is shifted to the retina on the visual axis, specifically in the macular area. However, since the refractive values of the peripheral areas of the retina are often different in the case of axial myopia, the focal plane or focus is shifted to the back of the retina in the peripheral areas by correction with the help of frame glasses or contact lenses. Since the focal plane matches the shape of the retina in the case of a healthy eye, the focal plane has a cup-like shape or corresponds to a focusing cup. In the case of correction with the help of frame glasses or contact lenses, this focusing cup will only be located in the macular area on the retina and will be shifted to the back of the retina in the peripheral areas of the retina, so that myopia in the peripheral areas is overcorrected.

[0006] However, during the growth of the eye during childhood, such correction of axial myopia may result in the growth of the eyeball being affected in such a way that the length of the eyeball continues to increase and axial myopia therefore develops more rapidly. Since during this growth phase the eye grows towards the focal point of the lens, it is generally believed that visual aids prevent the correction of the eye by growth. The displacement of the focusing cup in the peripheral area behind the retina clearly promotes this undesirable growth of the eye. It is conceivable that if the focusing cup could be displaced in the peripheral area of the retina in front of the retina with the help of a visual aid, the progression of axial myopia could be slowed down.

[0007] The present invention is therefore based on the object of specifying a method and a vision testing system by means of which the refractive properties of the eye can be determined more accurately.

[0008] This object is achieved by the method having the features of an embodiment of the present disclosure and by the vision testing system having the features of a preferred embodiment of the present disclosure.

[0009] The method for testing a subject's eyes of the present invention is performed with the aid of a vision testing system, which includes a first interferometric measurement device, a second topographic measurement device, a third refractive measurement device, and a processing device. The central axial length and peripheral axial length of the subject's eyes are measured with the aid of the first measuring device, the corneal curvature of the eye is measured with the aid of the second measuring device, and the refractive characteristics of the eye are measured with the aid of the third measuring device. The measurement data of the measurements of the first measuring device, the second measuring device, and the third measuring device are edited with the aid of the processing device, and the processing device outputs the measurement data.

[0010] In addition to objectively determining the refractive value, the method also allows the identification of measurement data regarding the topography or curvature of the cornea and the axial length of the eye. Thanks to these measurement data being simultaneously available, the person performing the examination can more easily evaluate the measured refractive value. Important for the present invention is that the central axial length, located in the visual axis area, and the peripheral axial length, located outside the visual axis area in the peripheral area of the retina, outside the fovea, are measured as axial length. If axial myopia is present, different measurement data for the central axial length and the peripheral axial length are typically generated. Based on the measurement data output by the processing device, the person performing the examination can then assess whether axial myopia is present or to what extent the retina in the fovea is deformed relative to the retina in the peripheral area. This means that a more comprehensive description of the eye being examined can be obtained by measuring the central axial length and the peripheral axial length. With the help of the measurement data obtained, improved optical correction or visual aids can then be calculated or selected.

[0011] During the measurement of the central axial length, the visual axis of the eye can be aligned with the optical measurement axis of the first measuring device, and during the measurement of the peripheral axial length, the visual axis of the eye can be tilted at an angle α>0° relative to the optical measurement axis of the first measuring device. The visual axis generally extends from the fovea in the central region of the retina. The peripheral region of the retina begins at the outer edge of the macula or the perifovea. Therefore, the peripheral axial length is measured starting from the peripheral region of the retina. In principle, the peripheral axial length can be measured outside the fovea at an angle α≥1°40′, outside the fovea at an angle α≥5°, outside the fovea at an angle α≥8°20′, or outside the perifovea at an angle α≥18°20′.

[0012] The corneal curvature and refractive properties of the eye can be measured while the visual axis of the eye is aligned with the optical measurement axis of the first measuring device and / or while the visual axis of the eye is tilted by an angle α (α ≥ 0°) relative to the optical measurement axis of the first measuring device. If the eye is tilted by an angle α relative to a vision testing system for measuring central axial length and for measuring peripheral axial length, the corneal curvature and refractive properties of the eye can be measured not only during central axial length measurements but also during peripheral axial length measurements. Measurements of the refractive properties of the eye are then generated, specifically for the peripheral retinal region where the peripheral axial length is measured. In this way, the optical system for testing the eye becomes more precise.

[0013] During the measurement of peripheral axial length, the visual axis of the eye can be tilted relative to the optical measurement axis of the first measuring device by an angle α of 20° ±10°. This relatively strong tilt of the visual axis relative to the optical measurement axis advantageously allows for examination of the peripheral region of the retina or the correspondingly curved focusing cup of the eye. The measurement data obtained in this region allows the person performing the examination to determine or assess myopia or axial myopia.

[0014] The peripheral axial length can be measured for different inclinations of the eye's visual axis relative to the optical measurement axis of the first measuring device (the angle α can be varied in 5° increments). This allows, for example, the peripheral axial length of the eye to be measured at multiple points on the retina. These measurement points can also be distributed on concentric circles about the visual axis, thereby obtaining a large number of measurement data for individual peripheral axial lengths. If the refractive properties of the eye are also measured during each individual measurement of the peripheral axial length, the optical system of the eye can be fully covered by the measurement data.

[0015] A fixation device of the vision testing system can be used to display a peripheral fixation mark on which the eye can focus, and in this way, the eye is fixed relative to the vision testing system. The peripheral fixation mark can be arranged in such a way that the optical axis of the eye or the visual axis of the eye is not aligned with the measurement axis of the first measuring device and is offset from the measurement axis of the first measuring device. For example, the fixation mark can be a light-emitting diode, through which a visual stimulus is presented to the subject in question, which then causes the eye to orient in the desired manner relative to the measurement axis of the first measuring device. The fact that the peripheral fixation mark is then located within the eye's close range and the eye is also adjusted to the peripheral fixation mark is not important for the measurement of the peripheral axial length. In contrast, determining the refractive properties of an eye adjusted to the close range is only subject to error and therefore requires paralysis of the ciliary muscle (ciliary muscle paralysis). In this way, the overall refractive state of the eye can also be determined using the measurement value of the peripheral axial length without performing ciliary muscle paralysis.

[0016] A central fixation mark at infinity on which the eye can be focused can be displayed with the aid of a fixation device of the vision testing system, wherein the eye can focus on the fixation mark and the eye can be fixed relative to the vision testing system. Correct positioning of the eye relative to the measurement axis of the vision testing system is necessary for accurate measurements by the vision testing system. Advantageously, here, the optical axis of the eye is aligned with the measurement axis of the vision testing system. Here, the eye can be oriented by presenting a fixation mark to the subject, and the subject can focus on the fixation mark at infinity. For example, the fixation mark can be an image representation of the object. A screen coupled to the optical path of the vision testing system can perform the image representation. It is crucial that the image representation of the subject's eye is at infinity so that the ciliary muscle of the eye is completely relaxed during the measurement with the aid of the vision testing system.

[0017] Advantageously, the eye can then also be tested without administering a ciliary muscle paralytic. Thus, the eye can be tested more easily and more quickly.

[0018] Different accommodation states of the eye of the subject can also be generated by means of the fixation device of the vision test system. Here, the central axial length and / or peripheral axial length of the eye and the refractive properties of the eye can then be measured for each of these accommodation states. The measured values obtained for the different accommodation states or different viewing positions of the eye can be used by the processing device to generate a comprehensive optical description of the eye. Improved optical corrections such as frame glasses, contact lenses, intraocular lenses, eye refractive intraocular lens implantation surgery (Phakic IOL), and laser surgery can be calculated using these measured values.

[0019] The eye can be measured using the first, second, and third measuring devices simultaneously. However, the axial length of the eye is measured in two steps.

[0020] If the axial length of the eye, the corneal curvature of the eye, and the objective refractive properties or refractive values of the eye are measured simultaneously in diopters, measurement errors that may occur when performing consecutive measurements with different measuring instruments can be eliminated. When the first, second, and third measuring devices perform measurements simultaneously, all the obtained measurement data refer to the state of the eye at that time, which makes it possible to compare measurement data obtained under the same conditions. When different devices are used or when measurements are performed sequentially, the eye is always oriented differently relative to the measurement axis or in different states of accommodation due to eye movements.

[0021] The central axial length can be compared with the peripheral axial length using a processing device, and the comparison result can be output together with the measurement data. The processing device performs the comparison, outputs the result of the comparison, and thus makes it easier for the person performing the examination to evaluate the obtained measurement data. The processing device includes data processing and display functions, such as a computer and a screen.

[0022] Furthermore, the processing device can compare the central measurement data with the peripheral axial length, and the comparison result can be output along with the measurement data. In addition to the central axial length, the central measurement data can also include measurement data on the objective refractive index and measurement data on the corneal topography or curvature. With this available measurement data, the examiner can more easily evaluate the measured refractive index.

[0023] The degree of refraction can be determined by comparison using a processing device. The degree of refraction can be used to categorize the identified axial length measurement values based on deviations from other measurement data. The processing device can identify the objective degree of refraction based on the measurement values or physical quantities of the measurement data. The measurement values can be weighted differently or correlated with one another. The processing device can output the objective degree of refraction, for example, on a screen, making it easier to assess the refractive properties of the eye.

[0024] With the aid of a processing device, the refractive power and / or refractive power gradient of the lens of the subject's eye can be determined from the measurement data. The refractive power of the lens of the eye changes with the subject's age. The refractive power of the lens of the eye can also vary at different points of the lens. By measuring the peripheral axial length and the refractive properties of the eye in at least a peripheral region, the refractive power of the lens of the eye in this region can also be determined, preferably the median or mean refractive power. The refractive power gradient is then generated for the measurement data of the centrally identified eye.

[0025] The processing device may provide a database with normal data, wherein the comparison of the measured data with the normal data can be performed by means of the processing device and the result of the comparison can be output. If the processing device performs the comparison of the measured data with the normal data, the deviation can be easily assessed based on the comparison result or the corresponding difference between the measured value and the normal value.

[0026] For example, if the measured values of corneal curvature deviate significantly from normal values, the examiner can more easily interpret the refractive value, which also deviates from normal values. In the example mentioned above, corneal curvature may be the cause of the refractive value. Furthermore, the examiner may identify excessive axial length as the cause of the refractive value. If the measured values of both the axial length and corneal curvature of the eye do not deviate from normal values, the refractive power of the lens, for example, may be different. In short, the fact that the measured values are obtained simultaneously makes it easy and quick to obtain accurate measurements and compare them with normal values.

[0027] Measurement data of eyes of normal people including the central axial length and / or peripheral axial length of the eyes, the corneal curvature of the eyes, and the refractive properties of the eyes can be used as normal data.

[0028] The normal data may correspond to the 50th percentile of a comparison group of persons for whose eyes the measurement data were identified. The normal data may also include all the measurement data of the comparison group, and the processing device can then output the exact deviation of the measurement data identified by means of the vision testing system from the 50th percentile of the comparison group, for example, and also output an indication of the percentile of the comparison group to which the measurement data can be assigned in each instance. The representative population average is understood to be the comparison group referred to herein as the normal population.

[0029] The processing device can in each instance compare the measured central axial length and / or peripheral axial length, curvature and refractive properties of the eye with normal data of the central axial length and / or peripheral axial length, curvature and refractive properties of the eye, and the processing device is configured to select the normal data for comparison based on the consistency of the central axial length and / or peripheral axial length, curvature or refractive properties with the measured measurement data.

[0030] Thus, the processing device can not only independently compare the measured data for axial length, curvature, and refractive properties of the eye with the corresponding records of normal data, but can also select from the database or normal data the eye or normal data and / or measured data associated with the eye that is closest to or corresponds to the measured data measured with the aid of the vision testing system. The processing device accordingly compares the eye measured with the aid of the vision testing system with the measured data of the eye stored in the database and outputs this comparison. Based on this comparison, the person performing the examination can more easily assess the extent to which the eye measured with the aid of the vision testing system deviates from the standard or already exhibits known symptoms.

[0031] The processing device can take the subject's age into account when comparing the measurement data. In each instance, the database containing normal data can also include normal data that can be assigned to a specific age. The processing device can then select normal data corresponding to the subject's age from the database containing normal data for comparison. The subject's age can be input into the processing device via an input device, for example, before or after the measurement. Due to the known relationship between myopia and age, taking the subject's age into account can enable a more accurate comparison of the measurement data. In addition, it is possible for the processing device to take into account the prevalence of myopia in a population, for example, when comparing the measurement data. In addition to age, work situation and temperament can also be taken into account.

[0032] Normal data can be used as measurement data for the subject, determined at a time prior to the measurement, including the peripheral and / or central axial length of the eye, the corneal curvature, and the refractive properties of the eye. Using a vision testing system, measurements can be taken on the same subject at different times, and the measurement data from each instance can be obtained and stored. This measurement data can then be used as normal data for comparison. This allows, for example, the determination of potential changes in the optical properties of the eye in question over a period of months or years. This makes it easier to identify the cause of a deterioration in refractive values, for example. Alternatively, however, the measurement data measured at each measurement time can also be compared with the normal data of a comparison group.

[0033] The processing device can use the measurement data from the first and / or second measurement devices to correct the measurement data from the third measurement device. As noted above, because refraction can be affected by many factors and environmental conditions, determining an objective refractive value is often difficult and prone to error. However, corneal curvature and axial length are measurements that are not affected by, for example, medications or brain activity. Therefore, the measurement data from the first and / or second measurement devices can advantageously be used to correct the measurement data from the third measurement device.

[0034] Thus, the processing device is configured to perform a plausibility check on the measured objective refractive values of the eye using the central and / or peripheral axial lengths of the eye and / or the corneal curvature of the eye, and to correct the refractive values according to the central and / or peripheral axial lengths and / or corneal curvature if the refractive values differ. The plausibility check can be performed based on a range indicator indicating the tolerance range for the individual measured values. The range indicator can also be stored in a database. The range indicator can be determined empirically or by statistical averaging based on standard deviations.

[0035] The vision testing system for testing a subject's eye according to the present invention includes a first measuring device, a second topographic measuring device, a third refractive measuring device, and a processing device. The first measuring device is used to measure the central axial length and peripheral axial length of the subject's eye, the second measuring device is used to measure the corneal curvature of the eye, and the third measuring device is used to measure the refractive properties of the eye. The processing device is configured to compile measurement data obtained from the measurements of the first, second, and third measuring devices. The vision testing system provides a fixation device that can be used to fixate the eye relative to the vision testing system so as to measure the central axial length or the peripheral axial length. Regarding the advantages of the vision testing system according to the present invention, please refer to the description of the advantages of the method according to the present invention.

[0036] It is particularly advantageous if the first, second and third measuring device are integrated into one device.

[0037] The fixation device comprises a central fixation mark configured to be displayed to the eye at infinity and configured to be focused on by the eye, the central fixation mark being arranged in such a way that when the eye focuses on the central fixation mark, the visual axis of the eye can be aligned with the optical measurement axis of the first measurement device. In principle, the first measurement device, the second measurement device, and / or the third measurement device can include the fixation device.

[0038] The fixation device may, for example, comprise a screen or a suitable projector, by means of which the central fixation mark can be visually presented to the eye at infinity. The central fixation mark may be an image representation of the object, thereby preventing the eye from focusing on a single point. The central fixation mark may be coupled to the optical path of the vision testing system via, for example, a beam splitter cube, such that the central fixation mark is visible to the subject.

[0039] In addition, the fixation device may include a peripheral fixation mark, which is configured to be displayed to the eye and configured to be focused on by the eye, and the peripheral fixation mark is arranged in the following way: when the eye focuses on the peripheral fixation mark, the visual axis of the eye can be tilted at an angle α relative to the optical measurement axis of the first measuring device, α>0°.

[0040] The peripheral fixation mark can be implemented by at least one light-emitting diode, which can be arranged eccentrically relative to the optical measurement axis on the side of the housing of the vision testing system facing the eye. The subject can then be positioned in front of the side of the housing of the vision testing system facing him or her, so that the eye movements of the subject's eye can be easily influenced by the light-emitting diode arranged eccentrically on or on the housing side of the vision testing system at a certain distance from the optical measurement axis, and the light stimulus is generated by the light-emitting diode. With the help of light-emitting diodes, the fixation mark can be implemented at particularly low cost. In addition, it is also conceivable to arrange multiple light-emitting diodes coaxially around the optical measurement axis to induce eye movements in the desired direction. In addition, multiple light-emitting diodes can also be attached to the housing side at different intervals relative to the optical measurement axis to achieve a pivoting of the eye by different angles α relative to the optical measurement axis. However, it is also possible to implement a light-emitting diode so that its relative position relative to the optical measurement axis is adjustable.

[0041] The fixation device may comprise an optical deflection element which is configured to pivot into the optical path of the central fixation mark and by means of which the optical path of the central fixation mark can be deflected in such a way that the central fixation mark can be displayed as a peripheral fixation mark located eccentrically relative to the optical measurement axis on the side of the housing of the vision testing system facing the eye. For example, if the central fixation mark is implemented by a screen or by another suitable projector, the light path from the screen can be deflected by means of an optical deflection element (which can be, for example, a mirror or a prism) so that the light path is no longer aligned with the optical measurement axis or extends parallel to the optical measurement axis. The optical deflection element can, for example, be a movable tilting mirror which can be pivoted into or out of the optical path of the central fixation mark as required. Incidentally, then, peripheral fixation marks which can be focused can also be presented to the eye at infinity.

[0042] The first, second, and third measuring devices can provide a common measurement axis that can be aligned with the optical axis of the eye. This shared measurement axis allows for particularly precise and easily comparable measurement data to be obtained. The alignment of the shared measurement axis with the optical axis of the eye is particularly advantageous for accurately determining the axial length of the eye.

[0043] The second and / or third measuring devices can provide distance measuring devices for measuring the distance between the eye and the second and / or third measuring devices. The distance measuring device can measure the distance between the refractive and / or topographic measuring devices and the eye being examined. This distance is important for correcting the measurement data. By obtaining this distance data, the subject can be correctly positioned in front of the vision testing system, or the measurement data measured using the refractive measuring device can be appropriately corrected. In this way, the distance measuring device can advantageously be used to measure the distance between the refractive measuring device and the cornea, particularly the front face of the cornea. Furthermore, the distance measuring device can also be used to determine the distance to the retina or the back face of the eye, taking into account the axial length of the eye. Alternatively, the distance to the back face of the cornea, the front face of the lens, and / or the back face of the lens can also be determined. The design of the distance measuring device is generally arbitrary and can be implemented using a topographic measuring device, a keratometer, or a Scheimpflug system.

[0044] The first measuring device may be an ultrasound measuring device or an interferometric measuring device.In principle, the first measuring device may be any type of measuring device by means of which the central axial length and the peripheral axial length of the eye can be measured.

[0045] Furthermore, the first measuring device may be an interferometer for optical coherence interferometry (OCT).

[0046] As an alternative, the first measuring device can be a partially coherent interferometer (PCI), which is configured to have a coherent light source, two measuring arms, and a detector device for simultaneously capturing the front face of the cornea and the front face of the retina or the optical boundary surface of the eye. Since the interferometer is provided with two measuring arms, it is possible to simultaneously detect the front face of the eye and the retina, and determine the relative distance between the front face and the retina, and thus determine the central and / or peripheral axial length of the eye. Here, it does not matter how far the eye is from the vision testing system, because the distance measurement or the axial length measurement of the eye can be performed independently of the distance from the vision testing system by means of the interferometer. In this way, possible interferometer measurement errors caused by the distance position of the eye relative to the vision testing system can be completely eliminated. Therefore, the axial length of the eye can be measured particularly accurately. In addition to the axial length of the eye, other optical boundary surfaces of the eye, such as the back face of the cornea, the front face of the lens, the back face of the lens, and the distance between these optical boundary surfaces can also be measured by means of the interferometer, and processed by the processing device. These measurement data can also be used by the processing device for comparison with corresponding normal data.

[0047] The second measuring device can be a keratometer and / or a Scheimpflug system. With the help of such a measuring device, the curvature or topography of the cornea of the eye can be determined.

[0048] The keratometer can provide an inspection device having an imaging device and a target. The target can be captured by the imaging device and can be realized as a circular, non-collimated fluorescent stripe and two collimated light spots. The design type of the keratometer's target is essentially arbitrary; light-emitting diodes are conceivable as the illuminator. The fluorescent stripe can be generated by a circular optical waveguide element. Generating multiple concentric annular fluorescent stripes is also conceivable. Advantageously, infrared light can be used as the light source for the target. The inspection device can be an imaging device coupled to the optical path of the keratometer or vision testing system via a beam splitter cube. The imaging device can capture an image of a parasitic target on the cornea of the eye. Using image processing, the corneal curvature can be easily derived from the parasitic target image, and the corneal curvature can be displayed by a processing device. Furthermore, the imaging device can be used as a setup camera or a general imaging device for a vision testing system, enabling precise alignment and orientation of the subject's eye.

[0049] A Scheimpflug system can include a projection device designed to illuminate the eye with a light gap, and an inspection device having an imaging device designed to capture a cross-sectional image of the light gap in the eye. The projection device and the imaging device are arranged relative to each other according to the Scheimpflug principle. The projection device can then project the light gap onto the eye, enabling illumination of the eye gap along the optical or visual axis. The imaging device, arranged according to the Scheimpflug principle, can capture a cross-sectional image of the light gap in the eye, generating a cross-sectional image that can optically capture the illuminated cross-sectional area of the eye or the anterior portion of the eye. The longitudinal cross-sectional image of the eye obtained in this manner can then advantageously reproduce the optical boundary surfaces of the cornea and lens. A processing device can readily calculate the relative distances between the optical boundary surfaces based on the image dataset obtained in this manner. Furthermore, the corneal curvature can be readily determined. The Scheimpflug system can implement a second measurement device, either alone or in conjunction with a keratometer.

[0050] Advantageously, the third measuring device may be an autorefractometer.

[0051] An autorefractometer can include a projection device and an inspection device. The projection device can be designed to project an illumination pattern onto the retina of the eye, and the inspection device includes a diffraction element and an imaging device and can be designed to capture the illumination pattern in the eye. The illumination pattern can be projected so that it is focused on the retina. Using an optical inspection device, the illumination pattern reflected from the retina can be inspected by the lens of the eye, resulting in an image pattern displayed on a photosensor of the imaging device. This image pattern is captured by the imaging device and analyzed using image editing. The illumination pattern projected onto the retina is characteristically deformed according to the refractive properties of the eye, allowing the refractive properties of the eye to be determined within the framework of an analysis of the illumination pattern based on a certain degree of deformation. The diffraction element can, for example, be an aperture plate having a plurality of holes arranged in a circular pattern. In each case, the optical path of the holes can be deflected onto the sensor of the imaging device via a deflection prism or a corresponding lens. Alternatively, the diffraction element can be a diffractive optical element (DOE).

[0052] Further advantageous embodiments of the vision testing system result from the description of the features contained in the preferred embodiments of the present disclosure in connection with the method of embodiments of the present disclosure.

[0053] Hereinafter, the present invention is described in more detail with reference to the accompanying drawings.

[0054] In the attached figure:

[0055] Figure 1 shows a schematic diagram of a vision testing system;

[0056] Figure 2 A cross-sectional view of an eye is shown.

[0057] Figure 1 A schematic diagram shows the configuration of a vision testing system 10, which includes a first interferometry device 11, a second topography device 12, a third refractive measurement device 13, and a processing device 14. The vision testing system 10 is arranged relative to the visual axis 15 or optical axis of an eye 16 to be examined in such a manner that the visual axis 15 does not correspond to or is offset from the measurement axis 17 of the vision testing system 10. Thus, the visual axis 15 of the eye 16 is tilted by an angle α relative to the optical measurement axis 17. The first interferometry device 11 is implemented by a partially coherent interferometer 18, the second topography device 12 is implemented by a keratometer 19, and the third refractive measurement device 13 is implemented by an autorefractometer 20.

[0058] The interferometer 18 essentially consists of a laser device 21 with a laser source 22 and a lens arrangement 23, a mirror arrangement 24 with a first mirror 25 and a second mirror 26, a detector arrangement 27 with a detector 28 and a lens arrangement 29, and a first beam splitter cube 30 and a second beam splitter cube 31. In particular, the second mirror 26 is arranged so that it can be displaced longitudinally along the double arrow 32, so that the length of the second reference arm 34 or the corresponding reference path can be changed. However, the first reference arm 33 is not embodied in such a way that its length can be changed. By displacing the second mirror 26, different areas of the eye 16 located on the visual axis 15 can be scanned. In particular, the central axial length (L ) of the eye 16 from the cornea 35 to the retina 36 or from the front side 37 of the cornea 35 to the back side 38 of the retina 36 can be measured. Z ) and peripheral axial length (L P ). A more in-depth description of the known functions of the partially coherent interferometer 18 is omitted here. In addition, measurement data describing the relative positions of optical boundary surfaces on the visual axis 15, such as the front surface 37 of the cornea 35, the back surface 39 of the cornea 35, the front surface 40 of the lens 41, the back surface 42 of the lens 41, and the back surface 38 of the retina 36, can also be obtained.

[0059] Keratometer 19 includes an inspection device 43 having a camera 44, a lens arrangement 45, and a target 46. In each instance, target 46 can be captured by camera 44 and realized by infrared light source 47 and lens arrangement 48. The infrared light source can be, for example, a light-emitting diode. Target 46 can realize two collimated light spots on cornea 35, both of which can be captured by camera 44. Target 46 is supplemented by a circular, non-collimated fluorescent stripe (not shown). Inspection device 43 is coupled to optical path 50 of vision testing system 10 via beam splitter cube 49.

[0060] The autorefractometer 20 is used to determine the refractive properties of the eye 16 and essentially comprises a projection device 51, an inspection device 52, and a fixation device 53. However, the fixation device 53 can also be implemented independently of the autorefractometer 20. With the aid of the optical projection device 51, an illumination pattern can be projected onto the retina 36 of the eye 16 and focused there. Here, the projection device 51 comprises an aperture plate 54, a lens arrangement 55, and an infrared light source 56. The illumination pattern is coupled to the optical path 50 of the vision testing system via a mirror 57 with an aperture plate 58 and a first beam splitter cube 59 of the autorefractometer 20. The optical inspection device 52 comprises a six-fold aperture plate 60, a deflection prism 61, a lens arrangement 62, and an imaging device 63. The image data captured by the imaging device 63 is processed and analyzed in the processing device 14 to determine the refractive properties of the eye 16. The inspection device 52 is coupled to the optical path 50 via a mirror 57 and a first beam splitter cube 59.

[0061] The fixation device 53 of the autorefractometer 20 is implemented by a screen 64 for displaying an image of the central fixation mark and a lens arrangement 65 for displaying the central fixation mark at infinity. The lens arrangement 65 can be moved in the direction of the optical path 70 of the screen 64 to enable different accommodation states or different viewing distances of the eye 16 to be set. A second beam splitter cube 66 makes it possible to couple the central fixation mark to the optical path 50. The first beam splitter cube 59 and the second beam splitter cube 66 are then components of the autorefractometer 20.

[0062] The fixation device 53 of the autorefractometer 20 further comprises a peripheral fixation mark, which is configured to be displayed to the eye 16 and is configured to be focused thereon by the eye 16 and which can be realized here by one of the light-emitting diodes 68. The light-emitting diode 68 is arranged eccentrically with respect to the optical measurement axis 17 on the housing side of the vision testing system 10 that faces the eye 16 and is not shown here. In order to show the peripheral fixation mark, one of the light-emitting diodes 68 is illuminated so that the eye 16 rotates due to the generated light stimulus to achieve an angle α of the visual axis 15 relative to the measurement axis 17 and to adjust to the peripheral fixation mark. In this way, the peripheral axial length L of the eye can then be measured with the aid of the interferometer 18. P Depending on which LED 68 is used to present the peripheral fixation marker, the peripheral axial length L can be measured at different inclinations of the visual axis 15 relative to the measurement axis 17 at an angle α. P The adjustment of the eye at close distance when the peripheral fixation mark is displayed is related to the peripheral eye axis length A P The measurement of the peripheral eye axis length A P The central axial length A was measured before or after Z , so the processing device 14 can perform the central axial length A Z and peripheral axial length A P The comparison is performed and the result of the comparison is output together with the remaining measurement data. P With A Z The person performing the examination can then assess the refractive properties of the eye 16 .

[0063] As an alternative, the fixation device 53 can be provided with a tilting mirror 69 which can be pivoted into the optical path 70 of the screen 64 and the lens arrangement 65 or of the central fixation mark. The optical path 70 can then be deflected by means of the tilting mirror 69 even before the second beam splitter cube 66 and directed at an angle α relative to the measuring axis 17 towards the eye 16. Thereafter, the central fixation mark is presented to the eye 16 as a peripheral fixation mark. It is advantageous here that the eye 16 can also adjust to the peripheral fixation marks at infinity. Then, in addition to measuring the peripheral axial length L PIn addition, the refractive properties of the eye 16 can also be measured without administering a cycloplegic agent with the aid of the autorefractometer 20. The fixation device 53 can also be rotatable about the measurement axis 17, so that a peripheral fixation marker can be presented at almost any point in the visual field of the eye 16.

[0064] Furthermore, a distance measuring device 67 is provided, which is implemented here by a keratometer 19 . The distance measuring device 67 comprises a target 46 and an inspection device 43 .

[0065] Using the vision testing system 10 shown here, measurements are performed simultaneously using a first interferometer measurement device 11, a second topography measurement device 12 and a third refractive measurement device 13, and a processing device 14 processes the measurement data of the measurements of the first interferometer measurement device 11, the second topography measurement device 12 and the third refractive measurement device 13. The processing device 14 provides a database with normal data, not shown here, and the measurement data is compared with the normal data with the help of the processing device 14 and the result of the comparison is output.

[0066] Figure 2 The eye 16 and the visual axis 15 are shown, along with a cup-shaped focal plane 72 of the eye 16, or a well-focused image in the focusing cup, with a focus 71 on the visual axis 15. Here, focus 71 is in front of the back surface 38 of the retina 36, making the eye 16 myopic. If the measuring axis 17 is pivoted relative to the visual axis 15 by an angle α, a focus 73 is produced that is closer to the back surface 38 than focus 71. This results in the shape of the cup-shaped focal plane 72. To achieve the best possible correction of the myopia of the eye 16, it is now necessary not only to shift focus 71 to the back surface 38 with the aid of a vision aid or invasive surgery, but also to adapt the cup-shaped focal plane 72 accordingly to the shape of the retina 36. This adaptation is only possible with knowledge of the optical properties of the eye 16 in the peripheral region of the retina 36. To prevent further progression of myopia, for example in adolescents, the cup-shaped focal plane 72 can be further curved by appropriately selecting a vision aid that exceeds the curvature of the retina 36. In addition to the refractive properties of the eye 16, the central axial length L of the eye 16 is also important. Z and peripheral axial length L P knowledge is particularly important here.

Claims

1. A method for testing an eye of a subject by means of a vision testing system (10), the vision testing system (10) comprising a fixation device (53), a first measuring device (11), a second topography measuring device (12), a third refraction measuring device (13) and a processing device (14), the method comprising: The eye is fixed relative to the vision testing system by means of the fixation device to measure the central axial length (L Z ) or peripheral axial length (L P ), the fixation device comprises a peripheral fixation mark, the peripheral fixation mark being configured to be displayed for the eye and focused on by the eye, such that the peripheral fixation mark is arranged in such a way that the visual axis of the eye is not aligned with the measurement axis of the first measurement device; The central axial length (L) of the eye (16) of the subject is measured by means of the first measuring device. Z ) and peripheral axial length (L P ); measuring the curvature of the cornea (35) of the eye by means of the second topographic measuring device; measuring the refractive properties of the eye by means of the third refractive measurement device; as well as The measurement data of the measurements of the first measuring device, the second topography measuring device and the third refractometry measuring device are processed by means of the processing device, which outputs the measurement data.

2. The method according to claim 1, It is characterized by: When measuring the central axial length (L Z ), the visual axis (15) of the eye (16) is aligned with the optical measurement axis (17) of the first measuring device (11), and the peripheral eye axis length (L P ), the visual axis of the eye is tilted by an angle α relative to the optical measurement axis of the first measuring device, α>0°.

3. The method according to claim 2, It is characterized by: The curvature of the cornea (35) of the eye (16) and the refractive properties of the eye are measured while the visual axis (15) of the eye is aligned with the optical measurement axis (17) of the first measurement device (11) and / or while the visual axis of the eye is tilted by the angle α, α>0°, relative to the optical measurement axis of the first measurement device.

4. The method according to claim 2 or 3, It is characterized by: When measuring the peripheral axial length (L P ), the visual axis (15) of the eye (16) is tilted relative to the optical measurement axis (17) of the first measuring device (11) by the angle α, which is 20°, ±10°.

5. The method according to any one of claims 1 to 3, It is characterized by: The peripheral axial length (L) of the eye is measured for different inclinations of the visual axis (15) of the eye (16) relative to the optical measurement axis (17) of the first measuring device (11). P ), wherein the angle α is changed in increments of 5°.

6. The method according to any one of claims 1 to 3, It is characterized by: The peripheral fixation mark on which the eye (16) can focus is displayed by means of the fixation device (53).

7. The method according to any one of claims 1 to 3, It is characterized by: A central fixation mark at infinity on which the eye (16) can focus is displayed by means of the fixation device (53), wherein the eye focuses on the central fixation mark and fixates the eye relative to the vision testing system.

8. The method according to any one of claims 1 to 3, It is characterized by: Different accommodation states of the test subject's eye (16) are produced by means of the fixation device (53).

9. The method according to any one of claims 1 to 3, It is characterized by: The first measuring device (11), the second topographic measuring device (12) and the third refractive measuring device (13) are used simultaneously to perform measurements on the eye (16).

10. The method according to any one of claims 1 to 3, It is characterized by: The central axial length (L Z ) and the peripheral axial length (L P ) and output the result of the comparison together with the measurement data.

11. The method according to any one of claims 1 to 3, It is characterized by: The central measurement data and the peripheral eye axis length (L P ) and output the result of the comparison together with the measurement data.

12. The method according to any one of claims 1 to 3, It is characterized by: The degree of diopter is determined by means of the processing device (14) from the comparison.

13. The method according to any one of claims 1 to 3, It is characterized by: The refractive index and / or the refractive index gradient of the lens (41) of the eye (16) of the test subject is determined from the measurement data by means of the processing device (14).

14. The method according to any one of claims 1 to 3, It is characterized by: The processing device (14) provides a database with normal data, wherein a comparison of the measurement data with the normal data is performed by means of the processing device and a result of the comparison is output.

15. The method according to claim 14, It is characterized by: The axial length (L) of the eye of a normal person including the center of the eye (16) Z ) and / or peripheral axial length (L P ), the curvature of the cornea (35) of the eye and the measurement data of the refractive properties of the eye are used as normal data.

16. The method according to claim 14, It is characterized by: The processing means (14) converts the measured central axial length (L) of the eye (16) into Z ) and / or peripheral axial length (L P ), curvature and refractive properties and the central axial length of the eye (L Z ) and / or peripheral axial length (L P ), curvature and refractive properties of the normal data, wherein the processing device is based on the central axial length (L Z ) and / or peripheral axial length (L P ), curvature or refractive characteristics with the measured data to select the normal data for the comparison.

17. A vision testing system (10) for testing an eye of a subject, the vision testing system (10) comprising a first measuring device (11), a second topographic measuring device (12), a third refractive measuring device (13) and a processing device (14), wherein the central axial length (L) of the eye (16) of the subject is measured by means of the first measuring device. Z ) and peripheral axial length (L P ), measuring the curvature of the cornea (35) of the eye by means of the second topography measuring device, measuring the refractive properties of the eye by means of the third refractive measuring device, the processing device being configured to process the measurement data of the measurements of the first measuring device, the second topography measuring device and the third refractive measuring device, the vision testing system providing a fixation device (53) capable of causing the eye to fixate relative to the vision testing system to measure the central eye axis length (L Z ) or the peripheral axial length (L P ), the fixation device comprises a peripheral fixation mark, which is configured to be displayed to the eye and focused by the eye on the peripheral fixation mark, so that the peripheral fixation mark is arranged in the following way: the visual axis of the eye is not aligned with the measurement axis of the first measuring device.

18. The vision testing system according to claim 17, It is characterized by: The first measuring device (11), the second topography measuring device (12) and the third refractive measurement device (13) are integrated into one device.

19. The vision testing system according to claim 17 or 18, It is characterized by: The fixation device (53) comprises a central fixation mark, which is configured to be displayed at infinity for the eye (16) and is configured to be focused on the central fixation mark by the eye, and the central fixation mark is arranged in the following way: when the eye focuses on the central fixation mark, the visual axis (15) of the eye is aligned with the optical measurement axis (17) of the first measuring device (11).

20. The vision testing system according to claim 19, It is characterized by: The peripheral fixation mark is arranged in such a way that when the eye focuses on the peripheral fixation mark, the visual axis (15) of the eye is tilted relative to the optical measurement axis (17) of the first measuring device by an angle α, α>0°.

21. The vision testing system according to claim 20, It is characterized by: The peripheral fixation mark is realized by at least one light-emitting diode (68) which is arranged eccentrically with respect to the optical measuring axis (17) on the housing side of the vision testing system (10) facing the eye (16).

22. The vision testing system according to claim 20, It is characterized by: The fixation device (53) comprises an optical deflection element (69) which is configured to be pivoted into the optical path (70) of the central fixation mark and to enable the optical path of the central fixation mark to be deflected using the optical deflection element in such a way that the central fixation mark can be displayed as a peripheral fixation mark located eccentrically relative to the optical measurement axis (17) on the side of the housing of the vision testing system (10) facing the eye (16).

23. The vision testing system according to claim 17 or 18, It is characterized by: The first measuring device (11), the second topographic measuring device (12) and the third refractive measuring device (13) provide a common measuring axis that can be coordinated with the visual axis (15) of the eye (16).

24. The vision testing system according to claim 17 or 18, It is characterized by: The first measuring device (11) is an ultrasonic measuring device or an interferometric measuring device.

25. The vision testing system according to claim 24, It is characterized by: The first measuring device (11) is an interferometer for optical coherence interferometry (OCT).

26. The vision testing system according to claim 24, It is characterized by: The first measuring device (11) is a partially coherent interferometer (18) designed with a coherent light source (22), two measuring arms (33, 34) and a detector device (27) for simultaneously capturing the front face (37) and the retina (36) of the eye (16).

27. The vision testing system according to claim 17 or 18, It is characterized by: The second topographic measuring device (12) is a keratometer (19) and / or a Scheimpflug system.

28. The vision testing system according to claim 17 or 18, It is characterized by: The third refractive measurement device (13) is an autorefractometer (20).

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