CN115381393B - Intraocular pressure measurement method and device based on equal-thickness interference - Google Patents
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- 230000004410 intraocular pressure Effects 0.000 title claims abstract description 54
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- 210000001742 aqueous humor Anatomy 0.000 claims abstract description 7
- 210000005252 bulbus oculi Anatomy 0.000 claims abstract description 5
- 210000002159 anterior chamber Anatomy 0.000 claims abstract description 4
- 210000000887 face Anatomy 0.000 claims abstract description 4
- 125000006850 spacer group Chemical group 0.000 claims description 19
- 238000000691 measurement method Methods 0.000 claims description 8
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- 208000010412 Glaucoma Diseases 0.000 description 7
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- 201000010099 disease Diseases 0.000 description 1
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- A61B3/00—Apparatus for testing the eyes; Instruments for examining the eyes
- A61B3/10—Objective types, i.e. instruments for examining the eyes independent of the patients' perceptions or reactions
- A61B3/16—Objective types, i.e. instruments for examining the eyes independent of the patients' perceptions or reactions for measuring intraocular pressure, e.g. tonometers
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- A—HUMAN NECESSITIES
- A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
- A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
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- A61B3/14—Arrangements specially adapted for eye photography
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- A61B2562/00—Details of sensors; Constructional details of sensor housings or probes; Accessories for sensors
- A61B2562/02—Details of sensors specially adapted for in-vivo measurements
- A61B2562/0247—Pressure sensors
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- A—HUMAN NECESSITIES
- A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
- A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
- A61B2562/00—Details of sensors; Constructional details of sensor housings or probes; Accessories for sensors
- A61B2562/16—Details of sensor housings or probes; Details of structural supports for sensors
- A61B2562/164—Details of sensor housings or probes; Details of structural supports for sensors the sensor is mounted in or on a conformable substrate or carrier
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Abstract
The invention relates to the technical field of medical equipment and instruments, and provides an intraocular pressure measurement method and device based on equal-thickness interference, wherein the intraocular pressure measurement method comprises the following steps: implanting the wedge-shaped sensor into the anterior chamber of an eyeball through an ophthalmic operation, wherein a bottom glass sheet faces to the direction of a crystalline lens, and a PDMS circular membrane at a round hole is directly contacted with intraocular fluid to induce intraocular pressure change; the image collector emits monochromatic light to the wedge-shaped sensor to generate an interference image, the PDMS circular film deforms when the intraocular pressure is increased, so that the optical path difference of reflected light changes, fringes of the interference image also change, and the image collector collects the interference image and then transmits the interference image to the computer for image processing and pressure resolving; based on the results of the image processing and the pressure calculation, an intraocular pressure value is obtained. The invention avoids complex process, reduces cost, has higher safety, high sensitivity and high portability, and can meet the requirement of measuring intraocular pressure in real time.
Description
Technical Field
The invention relates to the technical field of medical instruments, in particular to an intraocular pressure measurement method and device based on equal-thickness interference.
Background
Glaucoma is the second leading cause of blindness worldwide, and is characterized by unrecoverable and progressive vision loss, often found in late stages of the disease due to its asymptomatic and slow progression. In China, the incidence rate of glaucoma is 6.8%, and the glaucoma has close relation with the increase of age. With the growing population, the worldwide population of glaucoma is expected to reach 8000 ten thousand by 2030. To date, there is no effective treatment to recover from blindness caused by glaucoma, but if early prevention of the patient is possible and the condition is found in time, this would reduce the tremendous burden on the patient's home. It has been shown that glaucoma patients have peaks of ocular tension mainly at 8 to 10 in the morning and 12 to 6 in the evening, and that the probability of having peaks of ocular tension at sleep time is as high as 49.40 to 65.79%, whereas patients usually take ocular tension at the time of day going to hospital, and clinical examination provides a single tonometer measurement, requiring multiple measurements a day, so that complete changes in ocular tension of the patient cannot be obtained.
Currently, there are Goldman applanation tonometers, non-contact tonometers, and the like, but these tonometers have disadvantages of poor portability, inability to measure tonometers anywhere and anytime, large damage to cornea, and the like. In recent years, in order to meet the requirement of measuring intraocular pressure in glaucoma treatment, various research institutions at home and abroad are devoted to developing novel implantable intraocular pressure sensors, and common intraocular pressure sensors based on capacitance, piezoresistance, LCR circuits and microfluidics are available. However, such intraocular pressure sensors typically require complex circuit designs and require an implantable power supply, which presents associated challenges for capacitive and radio frequency based intraocular pressure sensors with size, range limitations, and power requirements.
Therefore, the situation that the intraocular pressure cannot be measured frequently limits the comprehensive grasp of the doctor on the condition of the patient, and also prevents the doctor from making a treatment scheme according to different conditions of the patient to a certain extent. Therefore, there is an urgent need to study a device that can satisfy the need of a patient to make tonometric measurements anywhere and anytime.
Disclosure of Invention
In view of the above, the present invention provides an intraocular pressure measurement method and device based on equal thickness interference, so as to solve the technical problems that the intraocular pressure measurement device in the prior art is inconvenient to operate and cannot measure intraocular pressure in real time.
In a first aspect of the present invention, there is provided an intraocular pressure measurement device based on equal thickness interference, the intraocular pressure measurement device comprising:
An image collector 1 and a wedge-shaped sensor 2,
The image collector 1 comprises an objective lens 101, a beam splitter 102, an LED monochromatic light source 103 and a CCD104, and is used for emitting monochromatic light emitted by the LED monochromatic light source 103 to emit the monochromatic light to the wedge-shaped sensor 2 to generate an interference image, and the image collector 1 collects the interference image and transmits the interference image to the computer 3 for image processing and pressure resolving;
The lens of the objective lens 101 is positioned at the forefront end of the image acquisition device and is used for amplifying an image; the beam splitter 102 is a cube with a side length of 25.4mm, is positioned behind the lens of the objective lens 101 and is used for deflecting the direction of monochromatic light; the LED monochromatic light source is monochromatic light with wavelength of 633nm, is positioned right below the beam splitter 102 and is used for generating interference images by the wedge-shaped sensor 2; the CCD104 is positioned at the rearmost part of the image collector 1 and is used for collecting interference images generated by the wedge-shaped sensor 101;
the wedge-shaped sensor 2 comprises a bottom glass sheet 201, a PDMS circular film 202, a spacer 203 and a top glass sheet 204 from bottom to top, and is used for generating interference images and then acquiring the interference images by the CCD104,
The bottom glass sheet 201 is a wafer, a round hole 205 is formed in the center of the wafer, the round hole 205 is coaxial with the bottom glass sheet 201, and a PDMS round film 202 is attached to the bottom glass sheet 201; the top glass sheet 204 is a wafer; a spacer 203 is arranged between the top glass sheet 204 and the PDMS circular film 202, the spacer 203 is positioned at the edge of the PDMS circular film 202, the top glass sheet 204 is tightly connected with the PDMS circular film 202 at one end, and the top glass sheet 204, the PDMS circular film 202 and the spacer 203 form a wedge-shaped air cavity 206.
In a second aspect of the present invention, there is provided an intraocular pressure measurement method based on equal thickness interferometry, the intraocular pressure measurement method comprising:
s1, implanting a wedge-shaped sensor into an anterior chamber of an eyeball through an ophthalmic operation, wherein the bottom glass sheet faces to the direction of a crystalline lens, and the PDMS circular membrane at a round hole is directly contacted with intraocular fluid to induce intraocular pressure change;
S2, the image collector emits monochromatic light to the wedge-shaped sensor to generate an interference image, when the intraocular pressure is increased, the PDMS circular film deforms, so that the optical path difference of reflected light changes, the fringes of the interference image also change, and the image collector collects the interference image and then transmits the interference image to a computer for image processing and pressure resolving;
And S3, obtaining the intraocular pressure value based on the results of the image processing and the pressure calculation.
Further, the PDMS circular membrane in S1 is a flexible membrane made of a biocompatible material.
Further, the edge of the PDMS circular film in S1 is provided with a spacer, and the top glass sheet is tightly connected with the PDMS circular film at the other end, including:
A strip with the height of 20 mu m made of SU-8 photoresist is used as a spacer, and is stuck on the surface of the PDMS circular film along the edge of the PDMS circular film; covering the top glass sheet on the PDMS circular film, wherein one end of the top glass sheet is overlapped with the photoresist, and the other end of the top glass sheet is overlapped with the PDMS circular film, so that a wedge-shaped air cavity is formed between the top glass sheet and the PDMS film; and sealing the joint of the top glass sheet and the bottom glass sheet by adopting PDMS liquid glue, and baking for 1h at 90 ℃ for curing to finish sealing the wedge-type sensor.
Further, the PDMS membrane at the circular hole in S1 is in direct contact with the intraocular fluid, and induces changes in intraocular pressure, including:
The monochromatic light is split into two beams of interference light after being emitted to the wedge-shaped sensor, one beam of light is reflected on the lower surface of the top glass plate, the other beam of light is transmitted into the air cavity, the reflection is generated on the upper surface of the PDMS circular film, and two interference light waves interfere on the lower surface of the top glass plate to generate an interference image;
when the intraocular pressure is increased, the PDMS circular membrane deforms, and deflects into the wedge-shaped air cavity, the distance between the wedge-shaped air cavity and the PDMS circular membrane is reduced, so that the optical path of reflected light is changed, and an interference image with interference fringes bent is generated.
Further, the step S2 includes:
The image collector is characterized in that monochromatic light of the image collector is split into two beams of interference light after being emitted to the wedge-shaped sensor, one beam of light is reflected on the lower surface of the top glass sheet, the other beam of light is transmitted into the air cavity, the upper surface of the PDMS circular film is reflected, two phases of light waves interfere on the lower surface of the top glass sheet, an interference image is generated, and the interference image is acquired by the CCD.
Further, the deformation amount Δh of the PDMS circular film is related to the elastic modulus of the PDMS circular film, the thickness of the elastic modulus film of the PDMS circular film, the poisson's ratio of the PDMS circular film, and the radius of the PDMS circular film.
Further, the acquiring of the intraocular pressure value in S3 includes:
Wherein Deltap is the pressure change, E is the elastic modulus of the PDMS circular film, d is the thickness of the elastic modulus film of the PDMS circular film, deltah is the deformation of the PDMS circular film, mu is the Poisson's ratio of the PDMS circular film, r is the radius of the PDMS circular film,
The deformation Δh of the PDMS circular film was calculated as follows:
wherein Δh is the height variation of the PDMS circular film, Δe is the maximum distance of the offset, λ is the incident light length,
Since the deformation amount of the PDMS circular film is also related to the wedge angle, the deformation amount of the PDMS circular film is obtained by the following calculation formula:
wherein alpha is the wedge angle,
The wedge angle is calculated as follows:
wherein alpha is a wedge angle, lambda is a corresponding optical path difference, e is a spacing of interference fringes,
Δh＝λ/2
The calculation formula corresponding to the change in the optical path difference is as follows:
wherein delta is the corresponding optical path difference change, and m is an integer.
Compared with the prior art, the invention has the beneficial effects that:
1. the invention reflects the change of intraocular pressure through the interference image change, realizes the passivity of the intraocular unit of the intraocular pressure detection device, avoids the complex insulating packaging and other technological processes of the active device, and reduces the technological difficulty and cost;
2. The whole body of the invention is made of biocompatible materials, so that the safety is higher;
3. the invention adopts the extremely thin PDMS film to induce the intraocular pressure change, and has high sensitivity;
4. the intraocular pressure measuring device is high in portability and simple to operate, and can meet the requirement of a patient for measuring intraocular pressure anytime and anywhere.
Drawings
In order to more clearly illustrate the technical solutions of the present invention, the following description will briefly explain the drawings used in the embodiments or the description of the prior art, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and other drawings can be obtained according to these drawings without inventive effort for a person skilled in the art.
FIG. 1 is a schematic diagram of an intraocular pressure measuring device based on equal thickness interference according to the present invention;
FIG. 2 is a flow chart of an tonometric measurement method based on equal thickness interferometry provided by the present invention;
FIG. 3 is a schematic diagram of a wedge sensor provided by an example of the present invention;
FIG. 4 is a schematic diagram of an image collector provided by the present invention;
FIG. 5 is a schematic view of the wedge sensor according to the present invention;
FIG. 6 is a side view of the wedge sensor structure provided by the present invention;
FIG. 7 is a schematic diagram of the distance between interference fringes and pressure change provided by an example of the present invention.
Detailed Description
In the following description, for purposes of explanation and not limitation, specific details are set forth such as the particular system architecture, techniques, etc., in order to provide a thorough understanding of the embodiments of the present invention. It will be apparent, however, to one skilled in the art that the present invention may be practiced in other embodiments that depart from these specific details. In other instances, detailed descriptions of well-known systems, devices, circuits, and methods are omitted so as not to obscure the description of the present invention with unnecessary detail.
An intraocular pressure measurement method and apparatus based on equal thickness interferometry according to the present invention will be described in detail with reference to the accompanying drawings.
Fig. 1 is a schematic structural diagram of an intraocular pressure measuring device based on equal-thickness interference.
As shown in fig. 1, the tonometric measurement apparatus includes:
An image collector 1 and a wedge-shaped sensor 2,
The image collector 1 comprises an objective lens 101, a beam splitter 102, an LED monochromatic light source 103 and a CCD104, wherein the LED monochromatic light source 103 emits monochromatic light to be emitted to the wedge-shaped sensor 2 to generate interference images, the image collector 1 collects the interference images and transmits the interference images to the computer 3 for image processing and pressure resolving,
The lens of the objective lens 101 is positioned at the forefront end of the image acquisition device and is used for amplifying an image; the beam splitter 102 is a cube with a side length of 25.4mm and is positioned behind the lens of the objective lens 101 and used for deflecting the direction of monochromatic light; the LED monochromatic light source is monochromatic light with wavelength of 633nm, is positioned right below the beam splitter 102 and is used for generating interference images by the wedge-shaped sensor 2; the CCD104 is positioned at the rearmost part of the image collector 1 and is used for collecting interference images generated by the wedge-shaped sensor 101;
The wedge sensor 2 comprises, in order from bottom to top, a bottom glass sheet 201, a PDMS circular membrane 202, spacers 203, a top glass sheet 204, for being acquired by the CCD104 after generating an interference image,
The bottom glass sheet 201 is a wafer, a round hole 205 is formed in the center of the wafer, the round hole 205 is coaxial with the bottom glass sheet 201, and a PDMS round film 202 is attached to the bottom glass sheet 201; the top glass sheet 204 is a wafer; a spacer 203 is arranged between the top glass sheet 204 and the PDMS circular membrane 202, the spacer 203 is positioned at the edge of the PDMS circular membrane 202, the top glass sheet 204 is tightly connected with the PDMS circular membrane 202 at one end, and a wedge-shaped air cavity 206 is formed by the top glass sheet 204, the PDMS circular membrane 202 and the spacer 203.
Based on the same conception, the invention also provides an intraocular pressure measurement method based on equal-thickness interference, which comprises the following steps:
Fig. 2 is a flowchart of an intraocular pressure measurement method based on equal thickness interference provided by the invention.
Fig. 3 is a schematic diagram of a wedge sensor provided by an example of the present invention.
FIG. 4 is a schematic diagram of the distance between interference fringes and pressure change provided by an example of the present invention.
Fig. 5 is a schematic structural diagram of a wedge-type sensor provided by the present invention.
Fig. 6 is a side view of the structure of the wedge sensor provided by the present invention.
As shown in fig. 2, the tonometric measurement method includes:
S1, implanting a wedge-shaped sensor into an anterior chamber of an eyeball through an ophthalmic operation, wherein a bottom glass sheet faces to the direction of a crystalline lens, and a PDMS circular membrane at a round hole is directly contacted with intraocular fluid to induce intraocular pressure change;
the method of the invention adopts the extremely thin PDMS film to induce the intraocular pressure change, and has high sensitivity.
The PDMS circular membrane in S1 is a flexible membrane made of biocompatible material.
Besides the PDMS circular membrane, the whole membrane is made of biocompatible materials, so that the safety is higher.
The edge of the PDMS circular film in S1 is provided with a spacer, and the top glass sheet is tightly connected with the PDMS circular film at the other end, comprising:
A 20 mu m-high strip made of SU-8 photoresist is used as a spacer and is stuck on the surface of the PDMS circular film along the edge of the PDMS circular film; covering a top glass sheet on the PDMS circular film, wherein one end of the top glass sheet is overlapped with the photoresist, and the other end of the top glass sheet is overlapped with the PDMS circular film, so that a wedge-shaped air cavity is formed by the top glass sheet and the PDMS film; and sealing the joint of the top glass sheet and the bottom glass sheet by adopting PDMS liquid glue, and baking at 90 ℃ for 1h for curing to finish the sealing of the wedge-type sensor.
The PDMS membrane at the round hole in S1 is directly contacted with intraocular fluid, and the response intraocular pressure changes include:
The monochromatic light is split into two beams of interference light after being emitted to the wedge-shaped sensor, one beam of light is reflected on the lower surface of the top glass plate, the other beam of light is transmitted into the air cavity, the reflection is generated on the upper surface of the PDMS circular film, and two interference light waves interfere on the lower surface of the top glass plate to generate an interference image;
when the intraocular pressure is increased, the PDMS circular membrane deforms, and deflects into the wedge-shaped air cavity, the distance between the wedge-shaped air cavity and the PDMS circular membrane is reduced, so that the optical path of reflected light is changed, and an interference image with bent interference fringes is generated.
Fig. 4 is a schematic diagram of an image collector provided by the present invention.
S2, the image collector emits monochromatic light to the wedge-shaped sensor to generate an interference image, the PDMS circular film deforms when the intraocular pressure is increased, so that the optical path difference of the reflected light changes, the fringes of the interference image also change, and the image collector collects the interference image and then transmits the interference image to the computer for image processing and pressure resolving;
After the monochromatic light of the image collector is emitted to the wedge-shaped sensor, the monochromatic light is divided into two beams of interference light, one beam of light is reflected on the lower surface of the top glass sheet, the other beam of light is transmitted into the air cavity, the upper surface of the PDMS circular film is reflected, two interference light waves interfere on the lower surface of the top glass sheet, an interference image is generated, and the interference image is acquired by the CCD.
And S3, obtaining the intraocular pressure value based on the results of the image processing and the pressure calculation.
The deformation amount Δh of the PDMS circular film is related to the elastic modulus of the PDMS circular film, the thickness of the elastic modulus film of the PDMS circular film, the poisson's ratio of the PDMS circular film, and the radius of the PDMS circular film.
The acquiring of the intraocular pressure value in S3 includes:
Wherein Deltap is the pressure change, E is the elastic modulus of the PDMS circular film, d is the thickness of the elastic modulus film of the PDMS circular film, deltah is the deformation of the PDMS circular film, mu is the Poisson's ratio of the PDMS circular film, r is the radius of the PDMS circular film,
The deformation Δh of the PDMS circular film was calculated as follows:
wherein Δh is the height variation of the PDMS circular film, Δe is the maximum distance of the offset, λ is the wavelength of incident light,
FIG. 7 is a schematic diagram of the distance between interference fringes and pressure change provided by an example of the present invention.
When the PDMS circular film is deformed to have a height of deltah, the interference fringes are shifted to have a maximum distance deltae. The essence of the interference fringe is that the connecting line of the same points of the optical path difference, namely the thickness h1 corresponding to the point A when the point A is not deformed is the same as the thickness h2 corresponding to the point B when the point B is deformed at the position with the largest interference fringe deflection, namely h1=h2, so the height difference from the point A to the point B is the thickness of the deformation of the wedge-shaped film at the point A, and the height of the protrusion can be obtained by measuring the distance of the interference fringe deflection, namely
The deformation Δh calculation formula of the PDMS circular film further includes:
wherein alpha is the wedge angle,
The wedge angle is calculated as follows:
wherein alpha is a wedge angle, lambda is a corresponding optical path difference, e is a spacing of interference fringes,
Δh＝λ/2
The calculation formula corresponding to the change in the optical path difference is obtained as follows:
After the monochromatic light is emitted to the wedge-shaped sensor, the monochromatic light is divided into two beams of interference light, one beam of light is reflected on the lower surface of the top glass plate, the other beam of light is transmitted into the air cavity, the reflection is generated on the upper surface of the flexible PDMS film, and two interference light waves interfere on the lower surface of the top glass plate to generate an interference image. When the pressure is increased, the flexible film deforms, and deflects into the air cavity, the distance between the air cavity and the flexible film is reduced, so that the optical path of reflected light is changed, and interference fringes are bent.
The relationship between the interference fringe distance change and the pressure is shown in fig. 7, the monochromatic light wave with the wavelength lambda is vertically incident into the wedge-shaped sensor, and the condition of the interference phenomenon of the two light beams is shown in the following formula:
wherein delta is the corresponding optical path difference change, and m is an integer.
The intraocular pressure measuring device is high in portability and simple to operate, changes of intraocular pressure are reflected through interference image changes, complex insulating packaging and other technological processes of active devices are avoided, and technological difficulty and cost are reduced.
The intraocular pressure measuring device is moved into the eyeball, so that the real-time intraocular pressure measuring requirement of a patient with specific eye diseases is met, the structure is simple, the carrying is convenient, and the safety performance of biological materials is high.
Example 1
As shown in fig. 5, the wedge sensor comprises a top glass piece 204, spacers 203, a pdms circular membrane 202, a bottom glass piece 201, and a central circular hole 205 in the bottom glass piece 201. The bottom glass sheet 201 is a glass wafer with a radius of 500 μm and a thickness of 200 μm, and a round hole 205 with a radius of 250 μm is made in the center of the bottom glass sheet 201 by laser; cutting a PDMS circular film 202 with the radius of 250 mu m on a PDMS film with the thickness of 30 mu m, and then attaching the PDMS circular film 202 on a bottom glass sheet 201 so that the PDMS circular film 202 can cover the round hole 205; a20 μm high SU-8 (photoresist) strip was made by photolithographic techniques and then attached to the PDMS film surface along the edges of the PDMS circular film 202; finally, a top glass sheet 204 with the radius of 500 mu m and the thickness of 200 mu m is covered on the PDMS circular film 202, one end of the top glass sheet 204 is overlapped with the photoresist, and the other end is overlapped with the PDMS circular film 202; and finally, sealing the joint of the top glass sheet 204 and the bottom glass sheet 201 by using PDMS liquid glue, and baking at 90 ℃ for 1h for curing to finish sealing the wedge-type sensor.
As shown in fig. 4, the image pickup 1 includes an objective lens 101, a beam splitter 102, a 633nm led monochromatic light source 103, and a ccd104. The lens of the objective lens 101 is positioned at the forefront end of the image collector 1 and is used for amplifying an image; the beam splitter 102 is positioned behind the lens of the objective lens 101 and is a cube with a side length of 25.4mm and is used for deflecting the direction of monochromatic light; the LED monochromatic light source 103 is monochromatic light with wavelength of 633nm, is positioned right below the beam splitter 102 and is used for generating interference images by the wedge-shaped sensor 2; the CCD104 is located at the rearmost of the image pickup 1 for picking up the interference image generated by the wedge sensor 2.
The actual value of the obtained intraocular pressure is 10-40mmHg.
Any combination of the above optional solutions may be adopted to form an optional embodiment of the present application, which is not described herein.
It should be understood that the sequence number of each step in the foregoing embodiment does not mean that the execution sequence of each process should be determined by the function and the internal logic, and should not limit the implementation process of the embodiment of the present invention.
The above embodiments are only for illustrating the technical solution of the present invention, and are not limiting; although the invention has been described in detail with reference to the foregoing embodiments, it will be understood by those of ordinary skill in the art that: the technical scheme described in the foregoing embodiments can be modified or some technical features thereof can be replaced by equivalents; such modifications and substitutions do not depart from the spirit and scope of the technical solutions of the embodiments of the present invention, and are intended to be included in the scope of the present invention.
Claims (8)
1. An tonometric measurement device based on equal thickness interferometry, comprising: an image collector (1) and a wedge-shaped sensor (2),
The image collector (1) comprises an objective lens (101), a beam splitter (102), an LED monochromatic light source (103) and a CCD (104),
The device is used for emitting monochromatic light from an LED monochromatic light source (103) to the wedge-shaped sensor (2) to generate interference images, and the image collector (1) collects the interference images and transmits the interference images to the computer (3) for image processing and pressure resolving;
The lens of the objective lens (101) is positioned at the forefront end of the image acquisition device and is used for amplifying an image; the beam splitter (102) is a cube with the side length of 25.4mm and is positioned behind the lens of the objective lens (101) and used for deflecting the direction of monochromatic light; the LED monochromatic light source is monochromatic light with wavelength of 633nm, is positioned right below the beam splitter (102) and is used for generating interference images by the wedge-shaped sensor (2); the CCD (104) is positioned at the rearmost part of the image collector (1) and is used for collecting interference images generated by the wedge-shaped sensor (101);
the wedge-shaped sensor (2) sequentially comprises a bottom glass sheet (201), a PDMS circular film (202), a spacer (203) and a top glass sheet (204) from bottom to top, is used for generating an interference image and then is acquired by the CCD (104),
The bottom glass sheet (201) is a circular sheet, a circular hole (205) is formed in the center of the circular hole, the circular hole (205) is coaxial with the bottom glass sheet (201), and a PDMS circular film (202) is attached to the bottom glass sheet (201); the top glass sheet (204) is a wafer; a spacer (203) is arranged between the top glass sheet (204) and the PDMS circular membrane (202), the spacer (203) is positioned at the edge of the PDMS circular membrane (202), the top glass sheet (204) is tightly connected with the PDMS circular membrane (202) at one end, and the top glass sheet (204), the PDMS circular membrane (202) and the spacer (203) form a wedge-shaped air cavity (206).
2. A tonometric measurement method based on the tonometric measurement apparatus according to claim 1, comprising:
s1, implanting a wedge-shaped sensor into an anterior chamber of an eyeball through an ophthalmic operation, wherein the bottom glass sheet faces to the direction of a crystalline lens, and the PDMS circular membrane at a round hole is directly contacted with intraocular fluid to induce intraocular pressure change;
S2, the image collector emits monochromatic light to the wedge-shaped sensor to generate an interference image, when the intraocular pressure is increased, the PDMS circular film deforms, so that the optical path difference of reflected light changes, the fringes of the interference image also change, and the image collector collects the interference image and then transmits the interference image to a computer for image processing and pressure resolving;
And S3, obtaining the intraocular pressure value based on the results of the image processing and the pressure calculation.
3. The tonometric measurement method according to claim 2, wherein said PDMS circular membrane in S1 is a flexible membrane made of biocompatible material.
4. The tonometric measurement method according to claim 2, wherein said S1 PDMS circular membrane has a spacer provided at the edge thereof, said top glass sheet being in close contact with said PDMS circular membrane at the other end thereof, comprising:
A strip with the height of 20 mu m made of SU-8 photoresist is used as a spacer, and is stuck on the surface of the PDMS circular film along the edge of the PDMS circular film; covering the top glass sheet on the PDMS circular film, wherein one end of the top glass sheet is overlapped with the photoresist, and the other end of the top glass sheet is overlapped with the PDMS circular film, so that a wedge-shaped air cavity is formed between the top glass sheet and the PDMS film; and sealing the joint of the top glass sheet and the bottom glass sheet by adopting PDMS liquid glue, and baking for 1h at 90 ℃ for curing to finish sealing the wedge-type sensor.
5. The tonometric measurement method according to claim 2, wherein said PDMS membrane at the circular hole in S1 is in direct contact with the intraocular fluid, inducing a change in tonus, comprising:
The monochromatic light is split into two beams of interference light after being emitted to the wedge-shaped sensor, one beam of light is reflected on the lower surface of the top glass plate, the other beam of light is transmitted into the air cavity, the reflection is generated on the upper surface of the PDMS circular film, and two interference light waves interfere on the lower surface of the top glass plate to generate an interference image;
when the intraocular pressure is increased, the PDMS circular membrane deforms, and deflects into the wedge-shaped air cavity, the distance between the wedge-shaped air cavity and the PDMS circular membrane is reduced, so that the optical path of reflected light is changed, and an interference image with interference fringes bent is generated.
6. The tonometric measurement method according to claim 2, wherein said S2 comprises:
The image collector is characterized in that monochromatic light of the image collector is split into two beams of interference light after being emitted to the wedge-shaped sensor, one beam of light is reflected on the lower surface of the top glass sheet, the other beam of light is transmitted into the air cavity, the upper surface of the PDMS circular film is reflected, two phases of light waves interfere on the lower surface of the top glass sheet, an interference image is generated, and the interference image is acquired by the CCD.
7. The tonometry method of claim 2, wherein the deformation Δh of the PDMS circular membrane is related to the elastic modulus of the PDMS circular membrane, the thickness of the elastic modulus membrane of the PDMS circular membrane, the poisson's ratio of the PDMS circular membrane, and the radius of the PDMS circular membrane.
8. The tonometric measurement method according to claim 6, wherein said obtaining of said tonometric value in S3 comprises:
Wherein Deltap is the pressure change, E is the elastic modulus of the PDMS circular film, d is the thickness of the elastic modulus film of the PDMS circular film, deltah is the deformation of the PDMS circular film, mu is the Poisson's ratio of the PDMS circular film, r is the radius of the PDMS circular film,
The deformation Δh of the PDMS circular film was calculated as follows:
Wherein Δh is the deformation of the PDMS circular film, Δe is the maximum distance of deflection, λ is the wavelength of incident light,
Since the deformation amount of the PDMS circular film is also related to the wedge angle, the deformation amount of the PDMS circular film is obtained by the following calculation formula:
wherein alpha is the wedge angle,
The wedge angle is calculated as follows:
wherein alpha is a wedge angle, lambda is a corresponding optical path difference, e is a spacing of interference fringes,
Δh＝λ/2
The calculation formula corresponding to the change in the optical path difference is as follows:
wherein delta is the corresponding optical path difference change, and m is an integer.
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| CN105934194A (en) * | 2013-12-16 | 2016-09-07 | 威里利生命科学有限责任公司 | Contact lens for measuring intraocular pressure |
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