JP2020110382A - Crystalline lens hardness measurement device - Google Patents

Abstract

To provide a crystalline lens hardness measurement device capable of measuring hardness of the crystalline lens with minimal invasiveness by utilizing an ultrasonic principle.SOLUTION: A crystalline lens hardness measurement device 30 has at least a probe part 10 formed by integrating a soft sheet 2 contactable with an eyelid 21 or a cornea 22 with an ultrasonic transducer 1 for transmitting an ultrasonic wave toward an eye and receiving a reflection signal reflected by the crystalline lens 23, and a computer part 5 for calculating sound speed in the crystalline lens 23 from thickness data of the crystalline lens 23 and the reflection signal, and operating a Young's modulus of the crystalline lens 23 based on a relation between the stored sound speed and the Young's modulus.SELECTED DRAWING: Figure 1

Description

The present invention relates to a lens hardness measuring device capable of measuring the hardness of a lens with minimal invasion by utilizing the ultrasonic principle.

The quality of vision is important for the transition to a super-aging society. However, presbyopia and cataract are inevitable problems for the elderly. Presbyopia and cataract are based on aging-related changes in the crystalline lens, and are morphologically changes in which the crystalline lens hardens and the elastic force decreases, resulting in a decrease in accommodation.

Brillouin scattering method, Raman scattering method, and optical coherence tomography (OCT) are known as methods for quantifying the aging of the crystalline lens. The Brillouin scattering method is to obtain the elastic state of the cornea and the crystalline lens by the confocal optical system. The Raman scattering method is used to determine the hardness of the crystalline lens and the progression of cataract from the water content of the crystalline lens. The optical coherence tomography (OCT) is capable of three-dimensionally grasping the condition of the retina and new blood vessels below it by continuously taking cross sections of the retina.

Further, in Patent Documents 1 and 2, the position of each tissue of the eyeball is obtained by transmitting an ultrasonic wave from an ultrasonic transducer in the ultrasonic probe and receiving and processing a reflection echo from each tissue of the eyeball. Thus, an ophthalmic ultrasonic diagnostic apparatus for measuring the axial length of the eye has been proposed. With these techniques, the thickness of the axial length and the thickness of the crystalline lens can be measured. In this ophthalmic ultrasonic diagnostic apparatus, when measuring the thickness of the crystalline lens, the thickness of the crystalline lens is measured with the sound velocity of the crystalline lens being constant.

JP 2001-187022 A JP, 2010-172538, A Utility model registration No. 3191253

The method for quantifying the aging change of the lens described above is effective in that certain information (elastic state, water content, three-dimensional shape) can be obtained, but the aging of the lens that causes presbyopia or cataract, etc. is effective. It has not been possible to accurately measure changes, that is, changes in the hardness of the lens.

Further, in the ophthalmic ultrasonic diagnostic apparatuses of Patent Documents 1 and 2, since the tip of the ultrasonic probe used for measurement is used by directly contacting the cornea, the patient is anesthetized during measurement and the patient's eyes should be open. Is measured up to. In particular, this ultrasonic probe is a pen type and is long and slender, and in order to perform accurate measurement, it is necessary to contact the tip of the ultrasonic probe so that it does not tilt. In response to this situation, clinical means are expected to provide a method that can be accurately measured with minimally invasiveness. However, if the measurement is performed without anesthesia, the thickness of the lens changes due to a dynamic element that looks far or near, and it becomes impossible to accurately measure the thickness of the lens.

An object of the present invention is to provide a lens hardness measuring device capable of measuring the hardness of the lens with minimal invasion by utilizing the ultrasonic principle.

The lens hardness measuring device according to the present invention is a probe in which a flexible sheet that can come into contact with the eyelid or cornea and an ultrasonic transducer that transmits ultrasonic waves toward the eye and receives a reflection signal reflected by the crystalline lens are integrated. And a computer unit for calculating the Young's modulus of the crystalline lens based on the relationship between the stored sound velocity and the Young's modulus by calculating the acoustic velocity of the crystalline lens with the thickness data of the crystalline lens and the received reflection signal. , At least.

According to the present invention, the probe portion in which the flexible sheet and the ultrasonic transducer are integrated can be brought into contact with the eyelid or the cornea with minimal invasion. The computer unit receives accurate lens thickness data obtained by, for example, optical coherence tomography (OCT) measurement, and passes through the lens using the accurate thickness data and ultrasonic reflection signals. Calculate the speed of sound. Based on the stored correlation between the sound velocity and the Young's modulus, the Young's modulus of the crystalline lens can be calculated to evaluate the hardness of the crystalline lens. With this measuring device, the sound velocity of the lens that changes with age can be accurately measured, and the hardness of the lens can be evaluated easily and accurately with minimally invasiveness. This device is effective for evaluating the degree of progress of presbyopia and cataracts and the effect of drugs.

In the lens hardness measuring device according to the present invention, the flexible sheet is a flexible rubber-like material, the ultrasonic transducer has flexibility, and its tip is flush with the flexible sheet surface. And is exposed to the eyelid or cornea side in a non-protruding state. According to this invention, since the tip of the ultrasonic transducer having flexibility is flush with the flexible sheet surface and is a flexible integrated structure (probe portion) as a whole, only the ultrasonic transducer is used. The flexible rubbery material can be slid over the eyelid or cornea for measurement without directly contacting the eyelid or cornea. Further, unlike the conventional case, the ultrasonic transducer does not tilt.

In the lens hardness measuring device according to the present invention, the flexible sheet extends in a slender shape symmetrically with respect to the ultrasonic transducer. According to the present invention, it is possible to move the ultrasonic transducer while pressing the flexible sheet that is elongated symmetrically in a long and narrow shape with a finger.

The crystalline lens hardness measuring device according to the present invention includes a gel pad that can be provided between the probe unit and the eyelid when the probe unit is brought into contact with the eyelid. According to the present invention, the gel pad can be provided between the probe unit and the eyelids, avoids a dead zone due to the transmission signal transmitted to the eye, and the measurement data is overlapped in the transmission signal so that the measurement signal from the crystalline lens is removed. It is possible to prevent the reflected signal from becoming unmeasurable.

In the lens hardness measuring device according to the present invention, the sound velocity is calculated by dividing the time difference between the reflection signal at the lower part of the lens and the reflection signal at the upper part of the lens and the thickness data.

According to the present invention, it is possible to provide a lens hardness measuring device capable of measuring the hardness of the lens with minimal invasion by utilizing the ultrasonic principle. By this measurement, the progress of presbyopia, cataract, etc. and the effect of the drug can be evaluated quickly and easily.

It is a whole lineblock diagram explaining an example of a crystalline lens hardness measuring device. It is a schematic diagram which shows the example of the form which applies a probe part on an eyelid or a cornea. It is a section lineblock diagram showing an example of an ultrasonic transducer. It is a graph which shows the photograph of the lens of a pig eye, and the result of its sound velocity measurement (ex vivo). It is a graph which shows the result of sound velocity measurement of the lens of the rat of the 8th week, and the rat of the 79th week. 6 is a graph showing the relationship between the sound velocity and Young's modulus obtained in FIG. 5.

Hereinafter, a lens hardness measuring device according to the present invention will be described with reference to the drawings. The present invention is not limited to the following embodiments and examples as long as including the subject matter of the present application, and can be modified into various aspects.

As shown in FIG. 1, a lens hardness measuring device 30 according to the present invention transmits a flexible sheet 2 that can come into contact with an eyelid 21 or a cornea 22 and ultrasonic waves toward an eye and receives a reflection signal reflected by a lens 23. The ultrasonic velocity of the crystalline lens 23 is calculated from the probe unit 10 in which the ultrasonic transducer 1 is integrated, the thickness data of the crystalline lens 23, and the reflection signal, and based on the stored relationship between the acoustic velocity and the Young's modulus, It has at least the computer unit 5 for calculating the Young's modulus of the crystalline lens 23.

The lens hardness measuring device 30 can bring the probe unit 10 in which the flexible sheet 2 and the ultrasonic transducer 1 are integrated into contact with the eyelid 21 or the cornea 22 with minimal invasiveness. The computer unit 5 is input with accurate thickness data of the crystalline lens 23 obtained by measurement by, for example, optical coherence tomography (OCT), and utilizes the accurate thickness data and the reflection signal of the ultrasonic wave to generate the crystalline lens 23. Calculate the speed of sound passing through. Based on the stored correlation between the sound velocity and the Young's modulus, the Young's modulus of the lens 23 can be calculated to evaluate the hardness of the lens 23. With this lens hardness measuring device 30, the sound velocity of the lens 23 that changes due to aging changes can be accurately measured, and the hardness of the lens 23 can be evaluated easily and accurately with minimal invasiveness. This device is effective for evaluating the degree of progress of presbyopia and cataracts and the effect of drugs.

The components will be described below.

(Probe section)
The probe unit 10 is one in which a flexible sheet 2 that can come into contact with the eyelid 21 or the cornea 22 and the ultrasonic transducer 1 are integrated, and transmits ultrasonic waves toward the eye and is reflected by the lens 23. It is an integral structural element that receives a signal. The ultrasonic transducer 1 that constitutes the probe unit 10 means a converter that converts an electric signal into ultrasonic vibration, and is also called an ultrasonic vibrator. The probe unit 10 in which the ultrasonic transducer 1 and the flexible sheet 2 are integrated can bring the flexible sheet 2 into contact with the eyelid 21 or the cornea 22 with minimal invasion, and only the ultrasonic transducer 1 as in the conventional case. Does not have to be in direct contact with the cornea 22. In particular, when the eyelid 21 is contacted for measurement, it is preferable as compared with the case where the anesthesia is directly contacted with the cornea 22, and it is particularly preferable to employ the flexible ultrasonic transducer 1. Further, since the probe unit 10 is not a long and narrow pen type as in the related art, the ultrasonic transducer 1 does not tilt.

The structural form of the ultrasonic transducer 1 is not particularly limited, but is usually held in a cylindrical casing (not shown). The ultrasonic transducer 1 used in the present invention may be variously modified as long as it has the same layer structure as the ultrasonic transducer proposed in Patent Document 3. For example, the ultrasonic transducer 1 is, for example, a disc having a small diameter of about 1 to 3 mm and has flexibility, and the matching layer 11, the vibrator 12, and the damper material 13 are laminated in that order. Has been formed. An adhesive layer 14 may be provided between the matching layer 11 and the vibrator 12. A cable 3 for transmitting an applied voltage or a reflected signal is attached to the ultrasonic transducer 1 (see FIG. 1). A connection terminal 4 is provided at the other end of the cable 3.

The matching layer 11 is for contacting the eyelid 21 or the cornea 22 and improving the passage of ultrasonic waves to the eyelid 21 or the cornea 22. The constituent material of the matching layer 11 is preferably a resin material. The vibrator 12 is a member for generating ultrasonic waves, and is mainly composed of a piezoelectric element that generates ultrasonic waves based on an applied voltage input from the outside and a covering material that covers the piezoelectric element. For example, a flexible one in which an element such as PZT is composited with a resin such as epoxy can be preferably used. Especially, when the ultrasonic transducer 1 constituting the present invention has flexibility, eyelids are used. 21 and the cornea 22 are preferable. The damper material 13 suppresses free vibration in the vibrator 12, and is arranged at least in a region where the vibrator 12 is arranged. The damper material 13 functions to absorb the vibration of the vibrator 12 and quickly converge the vibration of the vibrator 12. The constituent material of the damper material 13 is not particularly limited, but a material having an acoustic impedance value close to that of the vibrator 12 and large attenuation can be preferably mentioned.

The flexible sheet 2 is a flexible rubber-like material. The tip 1a of the ultrasonic transducer 1 is provided so as to be flush with the surface of the flexible sheet, and is exposed to the eyelid 21 or the cornea 22 side in a non-projecting state. The flexible sheet 2 can be measured by sliding the flexible rubber-like material on the eyelid 21 or the cornea 22 without the ultrasonic transducer 1 alone directly hitting the eyelid 21 or the cornea 22. Further, unlike the conventional case, the ultrasonic transducer 1 does not tilt and hit.

As shown in FIG. 2, the flexible sheet 2 is elongated symmetrically about the ultrasonic transducer 1. The ultrasonic transducer 1 can be moved while pressing the elongated portions extending symmetrically in the left-right direction with a finger. The dimension of the elongated portion is not particularly limited, but the width is preferably about 3 to 10 mm and the entire length is preferably about 3 to 6 mm.

(Computer section)
The computer unit 5 calculates the sound velocity of the lens 23 based on the thickness data of the lens 23 and the received reflection signal, and calculates the Young's modulus of the lens 23 based on the stored correlation between the sound velocity and the Young's modulus. Is. The computer unit 5 may include or be connected to other devices that an ultrasonic measurement device having the transducer 10 normally has. Examples of such other devices include a display device (display), a pulser receiver, a preamplifier, a pulse generator, a battery, and a power supply.

The hardness of the crystalline lens 23 can be measured from the measured sound velocity result by previously creating a calibration curve showing the correlation between the sound velocity and the Young's modulus and inserting the coefficient into a mathematical formula. Since the sound velocity is faster when passing through a hard substance than when passing through a soft substance, as shown in Experiments 1 and 2 described below, by measuring the sound velocity of the crystalline lens 23 that correlates with hardness (Young's modulus), By simply measuring the sound velocity of the lens 23 of the patient with minimal invasiveness, the age-related change of the lens 23 can be evaluated. With such a simple method for evaluating aging changes, it is possible to evaluate with time the changes in the eyes and the effects of drugs caused by aging such as presbyopia and cataract.

The thickness data of the crystalline lens 23 is the thickness data of the crystalline lens 23 that is accurately measured by a measuring unit such as optical coherence tomography (OCT). The obtained thickness data is input to the data input unit 6 included in the computer unit 5. The present invention is characterized in that after the thickness of the crystalline lens 23 accurately measured by another device is input in advance, the sound velocity of the crystalline lens 23 that is not constant due to aging change is measured. The ultrasonic measuring device currently used in clinical practice is used for the purpose of measuring axial length, vitreous length, and anterior chamber depth, but this is measured under the condition that the speed of sound passing through each tissue is constant. Is different from the present invention in that.

(Gel pad)
The lens hardness measuring device 30 preferably includes the gel pad 8 provided between the probe unit 10 and the eyelid 21 or the cornea 22. By providing the gel pad 8 between the probe unit 10 and the eyelid 21 or the cornea 22, the dead zone due to the transmission signal transmitted toward the eye is avoided, and the measurement data is overlapped in the transmission signal and the It is possible to prevent the reflected signal from becoming unmeasurable. The gel pad 8 is also called an echo gel pad.

By using the gel pad 8 for measurement, the probe unit 10 is scanned directly on the eyelid 21 or the cornea 22 without directly contacting it, which is preferable as a minimally invasive measurement means. As the gel pad 8, various sheets can be used as long as they are sheet-like materials made of a polymer gel for acoustic coupling used for ultrasonic inspection. For example, a commercially available product containing a flexible urethane gel or the like as a main material can be arbitrarily selected and used. The gel pad 8 may be adhesive or non-adhesive, but these can be arbitrarily selected according to the usage mode. The thickness of the gel pad 8 is commercially available in the range of, for example, 3 mm to 20 mm, and those can be selected and used. The use of the gel pad 8 can eliminate the need for a contact medium such as glycerin.

The use of the gel pad 8 is advantageous in that it is possible to prevent the reflection signal from being mixed with the transmission signal in the measurement by the probe unit 10 and the thickness of the lens 23 cannot be measured. In such a case, by interposing the gel pad 8 between the probe unit 10 and the crystalline lens 23 as the measured object, the reflected signal is delayed so that the transmitted signal does not mix the reflected signal of the crystalline lens 23. You can The optimum reflected signal can be found by scanning the probe unit 10 on the gel pad 8 while monitoring with an ultrasonic flaw detector.

Hereinafter, the present invention will be described more specifically with reference to experimental examples.

[Experiment 1]
FIG. 4 is a graph showing a photograph of a lens of a pig eye and the result of its sound velocity measurement (ex vivo). The measured pig eye lens is a purchased product having an overall diameter (so-called axial length) of 36 to 40 mm, and FIG. 4(A) is a transparent lens having a thickness of 7 mm and an equatorial diameter of 11 mm, and FIG. 4) is an opaque crystalline lens having a thickness of 8 mm and an equatorial diameter of 11 mm obtained by irradiating the crystalline lens of FIG. 4(A) with an electromagnetic wave (700 W, 20 seconds) to make it pseudo opaque.

As for the thickness, the crystalline lens 23 is placed on a mounting jig, and an echo gel pad (commercially available product) having a thickness of 10 mm is arranged as the gel pad 8 on the crystalline lens 23. Measured. The thickness was measured in advance using a Leica OCT imaging system for preclinical research (Envis R-class), but it was in agreement with the result measured by the lens hardness measuring device 30. The sound velocity was measured simultaneously while measuring the thickness of the crystalline lens 23. Specifically, the matching layer 11 of the ultrasonic transducer 1 constituting the probe unit 10 is brought into contact with the crystalline lens 23, and the ultrasonic wave (frequency: 10 MHz) generated by the vibrator 12 is incident on the crystalline lens 23 to obtain the The reflected signal thus obtained was subjected to ultrasonic wave detection (manufactured by Ryoden Shonan Electronics Co., Ltd., model name: UI-27) to measure the propagation time difference between the lens upper part 23a and the lens lower part 23b to obtain the sound velocity. The vertical axis of FIG. 4 is the relative value (arb.unit) of the reception intensity of the ultrasonic wave when the maximum value is 100%, and the horizontal axis is 0 when the ultrasonic wave is transmitted and the reflected signal is It's time to return.

The sound velocity measures the time difference between the reflection signal (first peak) at the lens upper part 23a and the reflection signal at the lens lower part 23b (second peak), and the time difference is the time when the ultrasonic waves make a round trip to the lens 23. That is, the speed of sound was calculated by dividing the value obtained by doubling the thickness of the crystalline lens 23 by the time difference. In FIG. 4A, since the time difference between the reflected signals is 8.0 seconds, the reciprocating distance (thickness 7.0 mm×2)/8 μsec=1750 m/s. In FIG. 4B, since the time difference between the reflected signals is 7.6 seconds, the reciprocating distance (thickness 8.0 mm×2)/7.6 μsec=2150 m/s. Here, the speed of sound is expressed by the speed of sound (m/s)=thickness of crystalline lens×2 (mm)/time difference of reflected signal (μ seconds).

The sound velocity of the transparent crystalline lens that did not undergo age-related changes was 1750 m/s, and the acoustic velocity of the cloudy crystalline lens that caused pseudo-aging changes was 2150 m/s. Thus, since the sound velocity of the crystalline lens changes due to aging change, the method of evaluating the hardness of the crystalline lens under the constant sound velocity as in the conventional method is not accurate as the crystalline lens hardness measurement, and the device of the present invention, By accurately measuring the sound velocity of the lens that changes due to aging changes, the lens hardness can be measured and evaluated.

[Experiment 2]
FIG. 5 is a graph showing the results of sound velocity measurement of the lens of a rat 8 weeks old (7 eyes) and the lens of a rat 79 weeks old (6 eyes). FIG. 6 is a graph showing the relationship between the sound velocity and Young's modulus obtained in FIG. The sound velocity was measured by the same method as in Experiment 1. The Young's modulus is the result when the crystalline lens is pushed in the meridian direction with a load of 1 N at a speed of 0.2 mm/s and 15% of the original thickness is pushed in, and measured with a special elasticity measuring device.

From the results of FIG. 5, the sound velocity of the lens of the rat at 8 weeks of age is 1780.6±43.3 m/s, and the sound velocity of the lens of the rat at 79 weeks of age is 2063.8±180.4 m/s. there were. The Young's modulus of the 8-week-old rat was 7.72±0.99 kPa, and the Young's modulus of the 79-week-old rat was 10.49±3.02 kPa. The separately measured Young's modulus results and sound velocity results are summarized in FIG. A correlation (r=0.73, p=0.01) was recognized between the speed of sound and the Young's modulus. According to the present invention, the correlation between the sound velocity and the Young's modulus is stored in the computer in advance, so that the Young's modulus (hardness) can be evaluated only by measuring the sound velocity of the subject.

1 Ultrasonic Transducer 1a Tip 2 Flexible Sheet 3 Cable 4 Connection Terminal 5 Computer Section 6 Thickness Data Input Section 7 Memory Section 8 Gel Pad 10 Probe Section 11 Matching Layer 12 Transducer 13 Damper Material 14 Adhesive Layer 21 Eyelid 22 Cornea 23 crystalline lens 23a crystalline lens upper part 23b crystalline lens lower part 30 crystalline lens hardness measuring device

Claims (5)

A probe unit that integrates a flexible sheet that can contact the eyelid or cornea and an ultrasonic transducer that transmits ultrasonic waves toward the eye and receives a reflection signal reflected by the lens, and the thickness data of the lens. A lens hardness measurement, which comprises at least a computer unit that calculates the sound velocity of the crystalline lens with the reflection signal and calculates the Young's modulus of the crystalline lens based on the relationship between the stored sound velocity and the Young's modulus. apparatus. The flexible sheet is a flexible rubber-like material, the ultrasonic transducer is flexible, and its tip is flush with the surface of the flexible sheet and does not project to the eyelid or cornea side. The lens hardness measuring device according to claim 1, which is exposed in a state. The lens hardness measuring device according to claim 1 or 2, wherein the flexible sheet extends in a slender shape symmetrically about the ultrasonic transducer. The gel pad according to any one of claims 1 to 3, further comprising a gel pad that can be provided between the probe unit and the eyelid when the probe unit is brought into contact with the eyelid. Lens hardness measuring device. The sound velocity is calculated by dividing the time difference between the reflection signal at the lower part of the lens and the reflection signal at the upper part of the lens and the thickness data, according to any one of claims 1 to 4. The described lens hardness measuring device.