Method for deriving physiologically correct biometric data of an eye

Abstract

The invention relates to a method for collecting biometric measurement data of an eye based on different measurement modes, which method enables physiologically correct, representative and robust biometric measurement data. In the method according to the invention, the measurement data of the individual measurement variables are recorded continuously during the measurement time with as high a repetition rate as possible, and the dynamic behavior of the eye is also recorded with as high a repetition rate as possible. The individual phases of the eye dynamics are analyzed from the measurement values, the limits for the stable vision phase are defined, and only the measurement data of the individual measurement variables detected during the stable vision phase are output. Although the proposed method is particularly used for collecting biometric measurement data of an eye in the preparation of cataract surgery, the method can also be used in other fields of ophthalmology to produce error-free eye measurement data or recordings.

Description

Technical Field

[0001] This invention relates to a method for collecting biostatistical measurement data of the eye based on different measurement modes, which achieves physiologically accurate, representative and robust biostatistical measurement data. Background Technology

[0002] In the preparation for cataract surgery, different biostatistical measurements of the patient's eyes are required so that the appropriate refractive power for the intraocular lens (IOL) to be implanted can be calculated.

[0003] Therefore, various measuring devices are used based on known existing technologies. Many of these measuring devices are based on optical methods, such as:

[0004] • A keratometer / ophthalmic meter used to measure the surface curvature of the cornea.

[0005] • A topography device used to measure the entire cornea.

[0006] • An automated refractometer used to determine an individual's refractive error (visual acuity test).

[0007] • A pupillometer used to determine the width and light reflex of the pupil.

[0008] • A pachymeter used to measure corneal thickness.

[0009] ·etc.

[0010] To determine distances within the eye, measurement devices based on ultrasound or similar optical methods are known. These devices include: a cyclotron camera, a slit lamp, and measurement devices based on optical coherence tomography (OCT), partial coherence interferometry (PCI), or similar methods.

[0011] To achieve high-precision non-contact measurements, solutions based on OCT (Optical Coherence Tomography) methods are commonly used in existing technologies. Here, measurements are performed using depth scans, rather than cross-sectional images as in the case of Xiangfulu cameras and slit lamps.

[0012] Furthermore, existing technologies have created combined measurement devices that integrate two or more measurement systems into a single device.

[0013] Therefore, exemplarily referring to equipment from Zeiss is provided. 700. This combined device uses a keratometer to determine the surface curvature of the cornea and OCT to determine the axial length, anterior chamber depth, and lens thickness. It also determines other eye parameters, such as the so-called white-to-white distance. Based on these measurements used to calculate the fundamental parameters of the IOL, calculations can be performed using various formulas or ray tracing.

[0014] Currently, high precision has been achieved in determining biostatistical measurements at the eye. Nevertheless, various sources of error still negatively impact the measurement results, leading to suboptimal calculations for the IOL to be implanted.

[0015] In particular, the implanted curved IOL is considered according to [2] in order to further optimize the calculation of the implanted IOL.

[0016] However, no further improvements have been found to date. The existing technology only proposes introducing multiple measurements and then averaging them to achieve more reliable results using the average measurement.

[0017] Based on current technology, the processing of biostatistical measurements of a patient's eyes follows the procedure below, in which the patient is requested to:

[0018] - Avoid blinking as much as possible after eyelid movement.

[0019] - Open your eyes as wide as possible, and

[0020] - Gaze at a static target (usually a point of light or an image).

[0021] Therefore, it is necessary to ensure the presence of a stable tear film, open the eyelids wide enough, and allow the eyes to gaze without accommodation.

[0022] After the patient's eyes are aligned with the measuring device, measurements can be performed at any time. Typically, the measurement data is detected within one second to avoid placing too much burden on the patient and to reliably attract their attention.

[0023] Therefore, measurement data detection is performed arbitrarily and is related to indicators processed by the operator or automatically, such as eye-to-measurement axis centering and achieving a clear image of the eye in the camera.

[0024] A disadvantage of this method is that the corneal surface or the optophysiological state of the eye at the actual time point of measurement data detection is unknown.

[0025] Unfavorable measurement timing can result in overly biased or completely incorrect measurements, which can lead to deterioration of visual function after IOL implantation.

[0026] It should be noted that, to date, biostatistical measurements have not adequately considered the dynamics of the eyes of living patients.

[0027] In principle, the dynamics of a living patient's eye have not been examined in more detail during these measurements, thus making it impossible to avoid measurement errors.

[0028] literature:

[0029] [1] Manual; “New Device IOL Master 700”; Carl Zeiss Medical AG; DE_32_010_000911; CZ-I / 2015, Germany.

[0030] [2] Author Hoffmann, Peter; “Preoperative diagnosis of cataract surgery in the case of implantation of toric lens”; Part III: Error sources - achievable accuracy; Ophthalmic Surgery 25:265-270 (2013).

[0031] [3] Authors Werkmeister, RM et al.; "Measurement of Tear Film thickness using Ultrahigh Resolution OCT"; Clinical Trials; IOVS2013; 5578-5583. Summary of the Invention

[0032] The objective of this invention is to develop a method for collecting biostatistical measurement data of the eye, ensuring that the data is physiologically accurate, representative, and robust. Furthermore, the measurement data should be correlated with the optophysiological state of the eye and should be recorded and evaluated as automatically as possible.

[0033] The objective is achieved by means of the proposed method for deriving physiologically correct biostatistical measurements of the eye by selecting dynamic measurement data, as follows: Measurement data of each measurement variable are continuously recorded at the highest possible repetition rate during the measurement period, and the dynamic behavior of the eye is also recorded at the highest possible repetition rate. The dynamic behavior of the eye is analyzed from the measurement data for each stage, a boundary is defined for the stable vision stage, and only the measurement data of each measurement variable detected during the stable vision stage are output.

[0034] Here, according to the present invention, the dynamic behavior of the eye is analyzed according to one, some, or all of the following criteria:

[0035] Tear film,

[0036] • The opening of the eyelids,

[0037] ·gaze,

[0038] • Visual accommodation, and

[0039] ·adapt.

[0040] Although the proposed method is particularly useful for collecting biostatistical measurements of the eye in preparation for cataract surgery, it can also be used in other areas of ophthalmology to produce error-free eye measurements or records. Attached Figure Description

[0041] The invention will now be described in more detail with reference to embodiments. For this purpose, the following is shown:

[0042] Figure 1 The image shows a static reflection image from a keratometer.

[0043] Figure 2 This illustrates the various stages of tear film dynamics in the eye during the five eyelid movement cycles.

[0044] Figure 3 The diagram shows measurements collected continuously within a continuous measurement window (each with a duration of approximately 0.5–1.5 seconds and approximately 5–15 individual measurements), with a typical individual measurement time of 0.1 seconds and a repetition rate of 10 Hz. These measurements are represented as boxes with gray and white markers numbered 0 to 9.

[0045] Figure 4 This shows a comparison of stable measurements collected from multiple measurement phases during multiple eyelid movement cycles.

[0046] Figure 5 This shows a view of two parallel measurement variables that are time-synchronized during multiple eyelid movement cycles.

[0047] Figure 6 Showing according to Figure 5 A view of the overall selection of measurements, but with the overall selection of measurements.

[0048] Figure 7 The image shows an OCT scan of the retina with a central fovea as a gaze examination during eye length measurement, and...

[0049] Figure 8 This diagram illustrates a comparison of the eye's condition with and without visual accommodation (left) and with visual accommodation (right). Detailed Implementation

[0050] In light of the prior art and the problems pointed out, the present invention proposes a solution that records the dynamic characteristics of the eye during biometric or refractive or other diagnostic measurements, and selects and provides only physiologically correct, available biometric parameters for further processing.

[0051] In the proposed method for deriving physiologically correct biostatistical measurements of the eye by selecting dynamic measurement data, the measurement data of each measurement variable are continuously recorded at the highest possible repetition rate during a measurement time of approximately 20 seconds (multiple eyelid movements).

[0052] According to the present invention, the dynamic behavior of the eye is continuously recorded with the highest possible repetition rate during the measurement period, the various stages of eye dynamics are analyzed, and the boundaries for the stable vision stage are defined.

[0053] As a result of this method, only the measurement data of each measurement variable related to the stable visual stage are output or considered for further calculations.

[0054] In particular, this biostatistical measurement data of the patient's eye is needed to calculate the refractive power of the appropriate intraocular lens (IOL) to be implanted.

[0055] The calculation of IOL is performed using one of the various existing calculation formulas or by means of ray tracing. For example, the following measurement data can be recorded using the described method:

[0056] - Radius and axis of the anterior cornea

[0057] - The radius and axis behind the cornea

[0058] - Measurement of corneal thickness

[0059] - Anterior chamber depth

[0060] - The radius and thickness of the lens

[0061] - Tilting of the lens

[0062] - Eye length,

[0063] -White to white distance,

[0064] - The distance from the retinal pigment epithelium to the internal limiting membrane.

[0065] - Pupil diameter, and

[0066] - Refractive power.

[0067] This list is merely illustrative and is not required to be complete.

[0068] In this context, it should be noted that the measurement time for continuously recording measurement data of each measurement variable is at least 1 second, and preferably 20 seconds.

[0069] According to the present invention, measurements are collected at different measurement time points, but respectively within the stable visual range C, within a typical measurement window of approximately 0.5-1.5 seconds using the measuring device, and by averaging approximately 10-15 individual measurements. Measurements derived from the average of the measurement window within the stable visual range, as described above, derived from measurements performed directly on the corneal radius, are used to represent the patient's stable visual range. As an alternative to averaging measurements formed at different measurement time points within the stable visual range C, the present invention proposes using the median or other aggregated values ​​of these measurements. Here, the decision of use is made based on the quality of the respective clinical outcomes. This filtered measurement result primarily achieves the following: collecting physiologically accurate and robust measurement data for the examined eye and identifying interfering dynamic effects of the eye.

[0070] Preferably, there should be multiple eyelid movement cycles throughout the entire measurement duration.

[0071] In cases where more measurement data is required, a longer measurement time can be introduced. However, in biostatistical examinations, the total measurement time should generally not exceed approximately one minute.

[0072] This ensures that neither the patient nor the examiner becomes overly stressed, guarantees the patient's focus, and minimizes the patient's optical radiation burden. Furthermore, the amount of data collected should not exceed a reasonable level within the limits of processability and measurement accuracy.

[0073] According to the present invention, the dynamic behavior of the eye is recorded according to one, more, or all of the following criteria:

[0074] - Tear film (indirectly caused by changes in corneal topometry values),

[0075] - The opening of the eyelids,

[0076] -gaze,

[0077] - Visual accommodation, and

[0078] -adapt.

[0079] In principle, it is proposed that at least one stable measurement phase be determined using at least one measurement mode.

[0080] Here, it is particularly advantageous that a stable measurement phase is determined by means of a measurement mode and is temporally related to at least one second measurement mode that is also affected by the dynamic curve of the first measurement data. Therefore, reliable measurement data from the second measurement mode and other measurement modes can also be guided with high reliability to the output of the measurement device, where the measurement data can also be averaged. Furthermore, the median or other aggregated values ​​of the measurement data can be used.

[0081] According to a favorable design scheme, the analysis of each stage of eye dynamics is carried out according to multiple different standards, and the boundary of the stable vision stage is derived from the intersection of the standards.

[0082] According to another advantageous design, the analysis of each stage of eye dynamics is performed according to multiple different criteria, with different boundaries defined for each criterion used to stabilize vision. Here, only the measurement data of each measurement variable are used, for example, to calculate the average and / or median and output, where the measurement data have been recorded during each stage of stabilizing vision.

[0083] According to the first embodiment, the tear film is recorded in response to the dynamic behavior of the eye by measuring and analyzing the radius of curvature of the cornea or anterior tear film between two eyelid movements. It should be noted here that the topography of the anterior tear film or corneal curvature is assessed as corneal topography or corneal curvature.

[0084] Due to the formation and dissolution of the tear film, there is a large dynamic of the eye. Therefore, according to [2], the blinking frequency of an adult is about 12 eyelid movements per minute, and the eyelids distribute the pre-corneal tear film (uniformly according to the prior art) across the surface of the eye in 0.3-1 seconds. On average, the tear film has a layer thickness of about 5 μm [3], which is no longer present when the tear film tears, and is therefore a variable. In order to measure the radius and topography of the anterior cornea, the reflectance image of the anterior cornea at the variable pre-corneal tear film is finally evaluated by means of optical reflectance methods based on dot patterns (keratometers / ophthalmometers) or based on so-called Plassid rings (topographic devices) to obtain measurements, where the anterior cornea has about 2 / 3 of the eye's refractive power.

[0085] to this end, Figure 1 The image shows a static reflective image of a keratometer with 18 measurement points arranged in three rings of different diameters, where the central ring is offset relative to the other rings.

[0086] Because of the large difference in refractive index between air and the tear film in front of the cornea, the thickness of the cornea and the length of the eye are always measured at this one point (the front of the cornea with the tear film), which experiences the dynamics of the tear film.

[0087] Therefore, existing technologies require patients to blink and then open their eyes so that measurements can be performed with a “good” tear film.

[0088] To date, all current measurement devices described above fail to account for the dynamic effects of the tear film, thus failing to obtain measurement results that are influenced by these dynamics and cannot represent physiologically accurate values ​​of the measured variables. This condition is a major source of error in biostatistical measurements of the eye.

[0089] The trigger for eyelid movement is receptors on the corneal surface that signal for a thin tear film (tear film tearing). This results in a deterioration of the optical system and visible vision. During eyelid movement, visual perception in the brain's responsible areas is completely suppressed. Shortly after eyelid movement, visual perception remains briefly restricted until a stable, clean tear film forms across the entire corneal surface. From this point onward, the brain actively perceives and processes visual stimuli. A short period of several seconds begins, during which human vision functions optimally. This period is quasi-static, in which measurements are very stable. After this period, corneal wetting deteriorates again (tear film drainage, dust particle deposition, etc.), and the described cycle begins anew.

[0090] to this end, Figure 2 The various phases of tear film dynamics at the eye during approximately five eyelid movement cycles are shown, with tear film dynamics presented as a time curve of measurements of corneal radius or anterior tear film radius using a keratometer.

[0091] Here, time is plotted on the horizontal axis, and the radius of curvature of the cornea or the anterior tear film, obtained using a keratometer, is plotted on the vertical axis. According to the invention, the radius of curvature very well reveals the relevant dynamics of the tear film for biostatistical measurements and can be divided into four repeatable phases. Here, phase A represents eyelid movement, phase B represents tear film stability, phase C represents stable visual range, and phase D represents tear film tearing.

[0092] Alternatively or additionally, instead of the radius of curvature of the cornea or the pre-corneal tear film, an axis with a similarly varying radius during the eyelid movement cycle can also be shown on the vertical axis.

[0093] According to the present invention, it is first proposed that the radius of curvature be calculated by corneal curvature measurement using only measurement data from the stable visual range (stage C), and the measurement data from stages A, B and D be discarded.

[0094] A stable visual stage is particularly relevant if the variation in corneal curvature or the radius R of the anterior tear film is within a tolerance of R < + / - 1%. If this limitation prevents the collection of measurements in individual cases of pathological cornea, the tolerance can be increased to approximately < + / - 5%. Conversely, if sufficient measurements are available, the tolerance can be limited to approximately < + / - 0.5% to allow for the collection of more accurate measurements.

[0095] Figure 3The diagram also illustrates the continuous collection of measurements (black measurement curves) according to the invention, with a typical individual measurement duration of approximately 0.1 seconds and a repetition rate of approximately 10 Hz. Typically, the average and / or median is calculated from approximately 10-15 individual measurements. Each measurement window (shown as a small box) detects 10-15 individual measurements (measurement duration of 0.5-1.5 seconds), and then the average is calculated (obvious outliers in the measurements have been eliminated beforehand). Currently, in the prior art, measurement results derived from the average and / or median of the measurement windows are provided in the device IOLMaster without considering the dynamic behavior at the eye, and thus can have undesirable errors. Now, according to the invention, measurement data are detected individually during multiple eyelid movement cycles over a total measurement duration of approximately 20 seconds, with individual measurement durations of 0.5-1.5 seconds.

[0096] This view shows consecutive measurement windows (each with a duration of approximately 0.5–1.5 seconds and approximately 5–15 individual measurements), represented as boxes with gray and white markings numbered 0 to 9. Measurement windows shown only as adjacent white-marked boxes (numbered 3–7) and displaying the same mean and median (radius / axis of the anterior cornea) within approximately 1% tolerance can be associated with measurement phase C, which represents the patient's stable visual range during the eyelid movement cycle, and are used according to the invention for further measurement data processing. Measurement results derived from measurement windows 0–2 and 8–9, shown as gray-marked boxes, are discarded and can be associated with measurement phases B and D.

[0097] Measurement phase C (or the measurement window marked in white) is defined as follows: the change in the average and / or median of one measurement window to the next (measured individually for 0.5-1.5 s) is less than, for example, a threshold of about 1%.

[0098] Figure 4 A comparison of measurements collected during multiple eyelid movement cycles across multiple measurement phases is shown as an improvement of the present invention. The average and / or median or other aggregated values ​​collected during multiple eyelid movement cycles from multiple self-stabilized measurement phases C are compared, and outliers representing stable but erroneous measurements are eliminated to output more reliable and representative measurements. At least three stable measurement phases C are set up for this evaluation.

[0099] This is another stage selected based on the measurement data according to the invention, which achieves the measurement of multiple eyelid movement cycles ( Figure 4 The 4+) were compared and observed, and for example, the measurement phase that was stable during the measurement window 3-6 in the eyelid movement cycle 3 was discarded (boxes marked in gray).

[0100] Parts 1, 2, 4, and 5 of the eyelid movement cycles generally provide measurement windows (marked with white boxes), which display the same mean and / or median (for the anterior corneal radius / axis) within approximately 1% tolerance. The mean and / or median can be correlated with measurement phase C, which represents the patient's stable visual range across multiple eye movement cycles, with increased reliability, and are used for further measurement data processing.

[0101] The method just described applies to the radius of curvature, i.e., to corneal surfaces without astigmatism. Because many corneas have astigmatism and thus a toric or ellipsoidal surface shape, according to the present invention, it is proposed that both radii of curvature R1 and R2, and their respective axes, are derived according to the proposed method. Here, both radii of curvature and their respective axes are simultaneously derived from the corresponding stable visual range.

[0102] Figure 5 A view showing two parallel measurement variables that are time-synchronized during multiple eyelid movement cycles:

[0103] - Upper part: According to Figures 2 to 4 The radius of curvature / axis of the anterior corneal tear film on the anterior side of the cornea during the four eyelid movement cycles (1-4).

[0104] -Lower section: Axial length (AL) obtained by means of OCT or PCI (partial coherent interferometry) through A and B scans performed by means of the IOLMaster700 device during 4 eyelid movement cycles (11-14).

[0105] Although the correct measurements of the anterior corneal radius of curvature were obtained in all stable phases C of the four eyelid movement cycles, simultaneous AL (eye length) measurements showed AL measurements exceeding the preset measurement tolerance (two dashed lines) in eyelid movement cycle 13. These measurements are no longer attributable to tear film dynamics but could be attributed, for example, to erroneous gaze by the patient during such a cycle. According to the invention, the AL measurements in eyelid movement cycle 13 are discarded, while the radius of curvature values ​​in stable phase C of the same eyelid movement cycle 3 can be used for measurement first.

[0106] Figure 6 It is based on Figure 5 A view of two parallel measurement variables with time synchronization during multiple eyelid movement cycles, but with overall selection for the data to improve measurement accuracy and reliability:

[0107] -Due to erroneous data in AL during eyelid movement cycle 13, the value of the radius of curvature in the same eyelid movement cycle 3 during the stable phase C is also discarded.

[0108] - As can be seen from the AL measurements in the lower figure, AL is measured as too large shortly after eyelid movement and too small shortly before eyelid movement, relative to the known intermediate range in the known stage C. In contrast, only the AL values ​​from stage C, measured synchronously in the upper figure, are available for evaluation; other AL measurements are discarded for further evaluation. This applies except for period 3 / 13. Figure 6 All other cycles shown.

[0109] According to the second implementation plan, the opening of the eyelids is examined in relation to the dynamic behavior of the eyes to ensure that the eyelids open sufficiently and that there are no possible shadows caused by the eyelashes.

[0110] The method described so far is based on the assumption that all points of the keratometer or all rings of the topography system can be detected completely in the reflective image. However, in practice, it often happens that individual reflective points or portions of the Placido ring fail to be useful for evaluation due to insufficient opening, especially due to insufficient upper eyelid opening, or also due to shadows caused by eyelashes, or due to local tear film tearing. This effect also leads to erroneous results regarding the radius of curvature and its axis. Furthermore, different image planes of different numbers of keratometer points or Placido rings can be recorded in multiple measurements.

[0111] Therefore, according to the present invention, in corneal curvature measurement and / or corneal topography or other measurement modes, such as OCT thickness measurement, deviations from the ideal complete image are statically and dynamically corrected within the measurement series in the evaluation of the measurement results.

[0112] Therefore, the following algorithm is specifically used:

[0113] -For example, if the localized area of ​​image failure is less than 10% of the total area of ​​the corneal topography, the surface of the localized area of ​​image failure is adapted based on adjacent topographic data, or

[0114] - If the localized area of ​​image failure exceeds 10% of the total corneal topography area, discard these localized data and do not display any data at the site of the image failure.

[0115] This is to account for this defect in the ideal data space of biostatistics and to avoid the impact of the defect on erroneous data output.

[0116] According to the third implementation plan, the dynamic behavior of the eye is considered by the following method: the eye length is continuously measured and only the measured value that does not exceed the preset tolerance within the preset measurement time is output.

[0117] As already described, the patient is asked to gaze at a static target (usually a bright spot) so that the length of the eye can be measured. The ability to gaze is related to the patient's awareness of the examination procedure, the degree of cataracts in the eye's lens and thus visual acuity, as well as the patient's ability to concentrate, which are often insufficient.

[0118] Furthermore, unconscious eye movements, known as saccades, are the cause of brief changes in gaze. Typically, human observation in static environments is characterized by the interaction of gazing and saccadic movements. Here, the moment when the eyes are relatively still relative to the object being observed is represented as gazing. The jump of the eyes to align with the fovea is represented as saccadic movements.

[0119] Salivation is a ballistic motion with speeds up to 900° / s, lasting from 2 milliseconds to approximately 80 milliseconds, and with an amplitude ranging from 2 to 50°. Therefore, both patient-associated inadequate gaze and involuntary saccades can prevent or only randomly achieve measurements along the visual axis of the eye.

[0120] Especially when measuring eye length and / or wavefront / refractive power, it is important that the eye is precisely focused on a target in the measuring device.

[0121] According to the invention, dynamic measurements of eye length are recorded multiple times over a period of approximately 1 second (similar to a defined measurement window in a corneal curvature measurement with approximately 0.5-1.5 seconds thereafter), a stable range of eye length is selected so that only the measured values ​​of eye length are averaged and / or the median is obtained and the contents recorded within the stable region are displayed.

[0122] The mean and median are illustrated by way of example in the instructions, but other aggregated values ​​may also be used in principle. Here, the clinical relevance of which aggregated value to use is determined.

[0123] It is specifically suggested that eye length measurements or other OCT-based measurements should be performed continuously over a period of at least 5 to approximately 60 seconds, particularly approximately 20 seconds, with the anterior tear film of the cornea as the measurement point.

[0124] From multiple measurements performed at repetition rates of at least 1 Hz to 10 kHz for B-scans of OCT and at least 1 kHz to 100 kHz for A-scans of OCT, only the following measurements will be evaluated:

[0125] - During a continuous measurement period of at least 1 second to approximately 20 seconds,

[0126] - Tolerance for measured eye length not exceeding + / - 50 μm or particularly preferred + / - 10 μm.

[0127] Therefore, under conditions of correct eye gaze, it is possible to ensure a physiologically stable measurement phase and to collect physiologically accurate measurements of eye length.

[0128] To supplement the third embodiment, a method is proposed that automatically identify the presence of the central pit using image processing algorithms, based on OCT retinal scans (see...). Figure 7 Accurate gaze identification is crucial. Axial length measurements are only used when the fovea is identified. If the fovea is not identified, all dynamically collected data during the measurement period is discarded. Regarding the lateral width of the retinal scan, it is suggested to use a small area of ​​approximately 1.5 mm and only examine the presence of the fovea within this small area. Furthermore, especially when the retinal scan is greater than 1.5 mm, it is suggested to assess the position of the fovea relative to the lateral scan and use only the following measurements of the AL, collected at the center of the fovea with a tolerance of + / - 0.5 mm. In the case of biometric asymmetric scans, the tolerance range should cover the expected position of the fovea.

[0129] Figure 7 This diagram shows an OCT retinal scan using the fovea as a gaze examination during AL measurement. The expectation here is that a scan of the fovea be acquired simultaneously with the AL measurement. If this is not possible with existing OCT techniques, the time series for the AL measurement and the corresponding foveal scans should be established promptly.

[0130] For example, a foveal scan is performed within at least one eyelid movement after an AL measurement. If both the AL measurement and the foveal scan are performed within an eyelid movement cycle with the tear film phase of AD, the reliability of the gaze examination is improved compared to a scan that detects the fovea in a subsequent eyelid movement cycle. If the foveal scan provides an erroneous gaze result, it is proposed that: AL measurements before and after the foveal scan be discarded; if the scan is correct, the AL measurement results before and after it are used first, based on this selection criterion.

[0131] According to the fourth embodiment, the dynamic behavior of the eye is taken into account based on its visual accommodation by continuously measuring the anterior chamber depth. According to the invention, only measurement data in which the anterior chamber depth has a value that is as large and stable as possible within a preset measurement time are output.

[0132] The eye's accommodation also causes dynamic conditions, particularly dynamic conditions of the lens shape and position, and to some extent, dynamic conditions of the corneal shape. Patients are required to view distant objects, for example, by gazing at an image, so that the desired non-visual accommodation state of the eye can be detected. However, so-called "device myopia" is known, where, despite this effort, the patient still triggers a certain degree of near-vision accommodation during examination at the device, and the measured values ​​shift in the direction of myopia. Specifically, this can explain the deviation of subjectively collected refractive power from that objectively measured by an automated refractometer, which is on the order of -0.5 dpt.

[0133] In order to exclude dynamic or device-induced myopia of visual accommodation when the eye is gazing at infinity (or set at the biometer), the present invention proposes, in particular, to determine the dynamic position of the anterior side of the eye's lens relative to the anterior side of the cornea or relative to the anterior side of the anterior tear film.

[0134] Under conditions of visual adaptation, it is reasonable to assume that the lens moves toward the cornea and that the anterior aspect of the lens bends more strongly. These two effects cause a shortening of the distance between the anterior cornea and the anterior aspect of the lens, i.e., a shortening of the anterior chamber depth. Therefore, according to the invention, the dynamically derived values ​​of the anterior chamber depth are examined over the longest possible stable range of the anterior chamber depth in order to select stable and physiologically representative measurements of the anterior chamber depth, along with data on the lens radius and lens thickness associated with it in this case.

[0135] to this end, Figure 8 This illustrates a schematic comparison of eye behavior under non-visual adaptation (left) and visual adaptation (right).

[0136] Instead of anterior chamber depth, lens thickness and / or lens radius and / or lens curvature can also be measured continuously over a measurement time of, for example, 1 to 20 seconds, since they are also altered by visual accommodation.

[0137] The state of non-visual accommodation of the eye is characterized by the following:

[0138] - Maximum anterior chamber depth

[0139] -Minimum lens thickness,

[0140] - The largest lens radius, and

[0141] - The minimum curvature of the lens surface.

[0142] According to the fifth implementation scheme, the dynamic behavior of the eye is considered in accordance with its adaptation as follows: for this purpose, the pupil diameter is continuously measured and only the measurement data in which the pupil diameter has a stable value within a preset measurement time is output.

[0143] In the case of the eye, adaptation is understood as the eye matching the dominant optical density in the visual field. In cases of differences in optical density, the eye adapts to the amount of incident light by contracting or dilating the pupil using the iris muscle. Therefore, when measuring the eye, the pupil diameter is related to both the room's brightness and the brightness of the gaze target in the measuring device.

[0144] Specifically, the eye adaptation can be used to: detect the position of the first Purkinje reflection image within the corresponding pupil based on the first Purkinje reflection image at the cornea, and then correlate the intersection of the visual axis and the cornea with the measurement data.

[0145] In known biostatistical measurement devices, pupil measurement is typically performed during the measurement of other eye parameters. However, pupil diameter data are only correlated with other measured eye parameters without further processing.

[0146] According to the present invention, it is proposed that the pupil diameter varies with different light intensities when observing a biostatistical measurement device. Therefore, for example, the pupil diameter can vary from approximately 2 mm to approximately 7 mm, and physiologically correct measurements can be performed separately based on all the parameters described herein.

[0147] Then, based on the measurement results, other biostatistics can be correlated with each pupil diameter, and the biostatistics can be dynamically realized due to the adaptation of the eye.

[0148] Furthermore, in pupillary measurement, it is proposed that the position of the first Purkinje reflex image within the corresponding pupil and the intersection of the visual axis and the cornea be correlated with the measurement result based on the first Purkinje reflex image at the cornea. Here, the intersection of the cornea and visual axis is recorded not only within the corresponding pupillary diameter but also relative to the stable limbal diameter or its midpoint. Changes in the first Purkinje reflex image within the pupillary diameter are a marker of unstable gaze during the measurement and, according to the invention, can also be used as a selection criterion for choosing physiologically stable measurement values ​​during stable gaze.

[0149] Furthermore, it is proposed that physiologically correct measurement data be filtered from dynamically recorded measurement data using multiple criteria, and that only measurement data corresponding to all selected criteria be directed to the output of the measurement device.

[0150] According to the present invention, the selection criteria can be designed to be adjustable. For example, the measurement accuracy of each parameter can be pre-selected at 0.1%, ... 1%, or 5%. Therefore, very high measurement accuracy requires the use of many selection criteria, while lower measurement accuracy can also be achieved in a short measurement time using individual selection criteria.

[0151] Therefore, according to the present invention, it is also proposed to measure corneal curvature as described above, and to dynamically determine eye length based on optical coherence tomography (OCT) by means of A-scan or B-scan during the time-linked process.

[0152] Here, a typical rate of 1kHz–100kHz is set for scan A, and a typical rate of 1Hz–10kHz is set for scan B. Furthermore, holographic OCT measurement technology can also be used. Since the location of the stable anterior corneal tear film and air boundary is an important measurement point for eye length and all other distances and lengths along the visual axis and / or optical axis, measurements of eye length recorded within a time range determined by dynamic corneal curvature measurement under stable visual acuity will now be evaluated.

[0153] Such recording can be performed multiple times within several stable ranges, and subsequently, for example, the average and / or median of the multiple measurements can be taken to obtain the optimal values ​​regarding physiological correctness and robustness.

[0154] The method according to the invention provides a solution for detecting physiologically accurate, representative, and robust biostatistical measurements of the eye based on various measurement methods. Here, the measurement data detection takes into account the optical physiological state of the eye and achieves automated data detection and evaluation.

[0155] The determination of the eye's optical physiological state is based on considerations of the eye's dynamic behavior. To this end, the eye's dynamic behavior is continuously recorded with the highest possible repetition rate during the measurement period. Boundaries for the stable vision phase are defined from the analysis of each stage of the dynamic behavior, and ultimately only the measurement data of each variable detected during the stable vision phase are output.

[0156] Here, the following should be proposed as the most important selection criteria for detecting the physiologically correct state of the eye:

[0157] • The correct tear film based on topographical measurement data.

[0158] • Correct eye length based on measurements obtained from tomographic scans under precise eye gaze.

[0159] • Correct values ​​of anterior chamber depth, lens thickness, lens radius, or lens curvature based on tomographic measurements.

Claims

1. A method for deriving physiologically correct biometric measurement data of an eye taking into account the dynamic behavior of the eye, characterized in that, The measurement data of the individual measurement variables are recorded continuously with a repetition rate of about 10 Hz for dynamic corneal curvature measurements, 1 Hz to 10 kHz for B-scans or 1 kHz to 100 kHz for A-scans or a combination of both, over a measurement time of about 20 s spanning multiple eye lid movement cycles, the individual phases of the dynamic behavior of the eye are automatically analyzed and a limit for the stable vision phase is defined and only the measurement data of the individual measurement variables detected during the stable vision phase are output.

2. The method of claim 1, wherein, The following measurement data are recorded: - topography measurement data, - tomography measurement data, - pachymetry measurement data, - refraction measurement data, and - biometric measurement data.

3. The method of claim 1, wherein, The dynamic behavior of the eye is analyzed according to one, some or all of the following criteria: - tear film, - opening of the eye lid, - gaze, - accommodation, and - adaptation.

4. The method of claim 1, wherein, The total measurement time for recording all measurement data can also be several minutes.

5. The method of claim 3, wherein, The limit for the stable vision phase is obtained from the analysis of the individual phases of the dynamic behavior of the eye according to the criteria.

6. The method of claim 3, wherein, The analysis of the individual phases of the dynamic behavior of the eye is carried out according to a plurality of different criteria and the limit for the stable vision phase is obtained from the intersection of the criteria.

7. The method of claim 3, wherein, The individual phases of the dynamic behavior of the eye are analyzed according to a plurality of different criteria and different limits for the stable vision phase are defined and only the measurement data of the individual measurement variables recorded during the different phases of stable vision are used for averaging and / or median value or for further aggregated values and output.

8. The method of claim 3, wherein, The tear film is recorded for the dynamic behavior of the eye by measuring and analyzing the radius of curvature of the pre-corneal tear film or the cornea and / or the associated axis between two eye lid movements, respectively.

9. The method of claim 7, wherein, The stable vision phase is present if the change in the radius of curvature of the cornea or the pre-corneal tear film R is within a tolerance of less than + / - 1%.

10. The method of claim 3, wherein, The opening of the eye lid is recorded for the dynamic behavior of the eye to ensure that the eye lid opens sufficiently large and in: - in case of a local image failure of less than 10% of the total area of the corneal topography, the face of the local image failure is adapted based on adjacent topography data; or - in case of a local image failure of more than 10% of the total area of the corneal topography, the local data are discarded and no data at the local image failure are displayed.

11. The method of claim 3, wherein, The dynamic behavior of the eye is considered according to the gaze of the eye, the eye length is continuously measured for the gaze and only the measurement data within a preset measurement time without exceeding a preset tolerance are output.

12. The method of claim 3, wherein, The dynamic behavior of the eye is considered according to the gaze of the eye, the eye length is continuously measured for the gaze and only the measurement data for which the fovea can be detected within a certain tolerance are output.

13. The method of claim 3, wherein, The eye length is continuously measured based on optical coherence tomography, wherein the measurement data to be output do not exceed a tolerance of + / - 50 pm over the measurement time.

14. The method of claim 13, wherein, The measurement data to be output does not exceed a tolerance of + / - 10 pm over the measurement time.

15. The method of claim 3, wherein, The dynamic behavior of the eye is analyzed taking into account the accommodation of the eye, so that the anterior chamber depth is measured continuously for the accommodation and only measurement data is output for the anterior chamber depth to have as large and stable a value as possible over a preset measurement time.

16. The method of claim 3, wherein, The lens thickness or the lens radius or the lens curvature is measured continuously over a preset measurement time without measuring the anterior chamber depth.

17. The method of claim 3, wherein, The dynamic behavior of the eye is analyzed taking into account the accommodation of the eye, so that the lens thickness is measured continuously for the accommodation and only measurement data is output for the lens thickness to have as small and stable a value as possible over a preset measurement time.

18. The method of claim 3, wherein, The dynamic behavior of the eye is analyzed taking into account the adaptation of the eye, so that the pupil diameter is measured continuously for the adaptation and only measurement data is output for the pupil diameter to have a stable value over a preset measurement time.

19. The method of claim 3, wherein, The position of the first Purkinje image within the respective pupil and / or iris is detected from the first Purkinje image at the cornea, so that the intersection of the visual axis with the cornea is associated with the measurement data.

20. The method of claim 19, wherein, Changes in the position of the first Purkinje image relative to the center of the pupil and / or the center of the iris are used to determine a stable phase of the gaze.

21. The method of any one of claims 1 to 9, wherein, Only biometric, topographic, tomographic, thickness measurement or refractive measurement data recorded in the stable vision phase is displayed, wherein mean values and / or median values are formed from a plurality of individual measurements or further aggregate values are formed.

22. The method of claim 21, wherein, Biometric, topographic, tomographic, thickness measurement or refractive measurement data is recorded in a time-coupled process.

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