JP2021171283A - Eyelid pressure measuring device - Google Patents

Abstract

To provide means for measuring a contact state of an eyelid with an eyeball and the pressure distribution.SOLUTION: An eyelid pressure measuring device is equipped with a cornea mounted member that can be mounted onto the cornea and an amorphous saccharide layer. 1) The cornea mounted member can come in contact with the cornea and cover the cornea. 2) The cornea mounted member is provided with a weight for preventing rotation on the cornea. 3) The amorphous saccharide layer is provided on the surface of the cornea mounted member.SELECTED DRAWING: Figure 1

Description

The present invention relates to an eyelid pressure measuring device. The eyelid pressure measuring device of the present invention can measure the contact state of the eyelid with the eyeball and the pressure distribution.

In order to elucidate the mechanism of occurrence of dry eye and corneal damage caused by wearing PC displays and contact lenses for a long time, a method for measuring the contact state and pressure between the eyelids (eyelids) and the anterior surface of the eyeball (cornea) is required. (Non-Patent Document 1). This pressure is commonly referred to as eyelid pressure ~ 30 mmHg (≈4 kPa), which is lower than blood pressure (Dry Eye Study Group / Definition and Diagnostic Criteria Committee for Dry Eye ,, New Ophthalmology, 34, 3 (2017), 309- 313.) Also, a flexible sensor that matches the shape of the eyeball is required. So far, there have been cases in which a strain gauge is incorporated into a contact lens by MEMS technology (Non-Patent Document 2 and Non-Patent Document 3), and an application of a tactile sensor (Non-Patent Document 1). It was difficult to grasp the contact state of the eyelids with the eyeball and the pressure distribution, only by measuring the static pressure locally on the sensor.

Sakai E, Shiraishi A, Yamaguchi M, Ohota K, Ohashi Y, Eye & Contact Lens, 38,5 (2012), 326-330. Alyra J. Shaw, Michael J. Collins, Brett A. Davis, and Leo G. Carney, Investigative ophthalmology & visual science, 51, 4 (2010), 1911-1917. Alyra J. Shaw, Brett A. Davis, Michael J. Collins, and Leo G. Carney, IEEE Transactions on Biomedical Engineering, 56, 10 (2009), 2512-2517.

As described above, in order to elucidate the mechanism of occurrence of dry eye and corneal damage, a device capable of measuring the contact state of the eyelid with the eyeball and the pressure distribution is required. The present invention has been made against such a background, and an object of the present invention is to provide a means for measuring an eyelid pressure distribution.

As a result of diligent studies to solve the above problems, the present inventor attaches a device having an amorphous sucrose layer on a contact lens to the cornea and blinks, in response to contact with the eyelids. It has been found that scratch marks are formed on the amorphous sucrose layer, whereby the eyelid pressure distribution can be measured, and the present invention has been completed.

That is, the present invention provides the following (1) to (4).
(1) An eyelid pressure measuring device provided with a corneal mounting member that can be mounted on the cornea and an amorphous saccharide layer. 1) The corneal mounting member can contact the cornea and cover the cornea. 2 ) The corneal mounting member is provided with a weight for preventing rotation on the cornea, and 3) the amorphous saccharide layer is provided on the surface of the corneal mounting member. An eyelid pressure measuring device.

(2) The eyelid pressure measuring device according to (1), wherein the amorphous saccharide layer contains a food pigment.

(3) The eyelid pressure measuring device according to (1) or (2), wherein the amorphous saccharide layer is an amorphous sucrose layer.

(4) The eyelid pressure measuring device according to any one of (1) to (3), wherein the thickness of the amorphous sugar layer is 100 to 200 μm.

The present invention provides a novel eyelid pressure measuring device. The eyelid pressure measuring device of the present invention can measure the contact state of the eyelid with the eyeball and the pressure distribution.

Principle of measuring eyelid pressure distribution by a colored thin film coated on a contact lens. Measurement parameters for the abrasion test. The main structure of the abrasion tester. The appearance of the scraping tester. Specimen manufacturing process. (A) Mold preparation, (b) Casting of molten sucrose, (c) Stretching with a molded plate, (d) Cooling and peeling of the plate, (e) Deburring and completion. Molded plate with mold and PTFE tape attached (left), completed sucrose test piece (right). Sucrose test piece (top) and surface measurement line (bottom) during the scraping test. An example of a profile line in a cross measurement on the b line after 20 round trips. Dependence of the amount of decrease Δt on the number of round trips N. Dependence of reduction Δt on indenter pressure P. Dependence of reduction Δt on indenter velocity V. Buoyancy is generated by the high-speed movement of the indenter. Film thickness sensitivity to indenter pressure.

Hereinafter, the present invention will be described in detail.
The eyelid pressure measuring device of the present invention is a corneal pressure measuring device provided with a corneal mounting member that can be mounted on the cornea and an amorphous saccharide layer. It can be covered, 2) the corneal mounting member is provided with a weight for preventing rotation on the cornea, and 3) the amorphous saccharide layer is provided on the surface of the corneal mounting member. It is an eyelid pressure measuring device characterized by being used.

The corneal mounting member may have any shape as long as it can contact the cornea and cover the cornea, but usually has the same shape as commercially available contact lenses (soft and hard contact lenses), that is, , It is preferable that the lens shape is curved along the curved surface of the eyeball (particularly the cornea). When the corneal mounting member has a shape similar to that of a commercially available contact lens, the thickness thereof may be the same as that of a commercially available contact lens, but may be thicker than that of a commercially available contact lens. For example, the thickness of the corneal mounting member may be 130 to 180 μm or 230 to 280 μm.

The material of the corneal mounting member is not particularly limited and may be the same as that of a commercially available contact lens, but the corneal mounting member may be made of a completely different material because transparency is not required unlike contact lenses. .. For example, the material of the corneal mounting member can be an amorphous saccharide.

If the corneal mounting member rotates on the cornea due to blinking, the eyelid pressure may not be measured correctly. Contact lenses for astigmatism correction use a lens design called prism ballast that prevents the lens from rotating (Naoki Iwasaki, “Contact Lens Seminar 16. Astigmatism SCL Lens,” New Ophthalmology, 32 (9): 1299- 1300, 2015.). This is a lens design that prevents rotation by thickening the lower part of the contact lens, acting as a weight, and shifting the center of gravity downward. Even in the cornea mounting member, it is possible to prevent rotation by providing such a weight.

An amorphous sugar layer is provided on the surface of the corneal mounting member. The surface of the corneal mounting member is the surface opposite to the surface on which the corneal mounting member comes into contact with the cornea. The amorphous sugar layer usually covers the entire surface of the corneal mounting member, but may cover only a part of the surface.

As the amorphous saccharide, sucrose, glucose, fructose, trehalose and other saccharides that are amorphized can be used. Among these, it is preferable to use amorphous sucrose. Amorphous saccharides can be produced by heating a mixture of water and saccharides and then cooling them. The mixing ratio of water and saccharides, the heating temperature, and the heating time can be appropriately set according to the type of saccharides, the heating method, and the like. For example, when producing amorphous sucrose using a microwave oven (700 W), the mixing ratio of water and sucrose is 2 to 7 g, preferably 3 to 6 g of sucrose with respect to 1 g of water. The heating temperature can be 140-180 ° C. and the heating time can be 30-180 seconds, preferably 60-120 seconds.

The amorphous sugar layer preferably contains a food pigment. By containing the food pigment, it becomes possible to display the scratch marks of the amorphous sugar layer caused by the contact with the eyelids as a color change. The food pigment to be used is not particularly limited, and either a synthetic pigment or a natural pigment can be used. Synthetic pigments include, for example, Edible Red No. 2 (Amaranth), Edible Red No. 3 (Erythrosine), Edible Yellow No. 4 (Tartrazine), Edible Yellow No. 5 (Sunset Yellow FCF), and Edible Green No. 3 (Fast Green FCF). ), Edible Blue No. 1 (Brilliant Blue FCF), Edible Blue No. 2 (Indigo Carmine) and the like. Natural pigments include, for example, caramel pigment, oyster pigment, turmeric pigment, Benibana pigment, Monascus pigment, tomato pigment, β-carotene pigment, palm oil carotene, marigold pigment, annatto pigment, capsicum pigment, gardenia pigment, monascus pigment, etc. Examples thereof include beet red pigment, red pepper pigment, grape peel pigment, anthocyanin pigment, spirulina pigment, perilla pigment, paprika pigment, cochineal pigment, and squid pigment.

The thickness of the amorphous saccharide layer is not particularly limited as long as it causes scratch marks in response to contact with the eyelids, but is preferably 100 to 200 μm.

The eyelid pressure measuring device of the present invention can be produced, for example, as follows.
1) Prepare an upper mold (concave curved surface) and a lower mold (convex curved surface) having a curved surface having the same curvature as the corneal mounting member, and a cylindrical mold in which these molds can be accommodated.
2) Install the corneal mounting member on the lower mold inside the cylindrical mold.
3) The molten amorphous saccharide is dropped onto the corneal mounting member. By controlling the dropping amount, the thickness of the amorphous sugar layer is controlled.
4) Immediately press down with the upper mold to mold the amorphous sugar layer and at the same time press it against the corneal mounting member.
5) After cooling, remove from the mold.

In the above manufacturing method, it is premised that an off-the-shelf product (commercially available contact lens) is used as the cornea mounting member, but the cornea mounting member may also be manufactured using a mold or the like.

The eyelid pressure measuring device of the present invention can be used, for example, as follows.
1) The subject is equipped with the eyelid pressure measuring device of the present invention.
2) Ask the subject to blink multiple times.
3) The eyelid pressure measuring device of the present invention is removed from the subject.
4) Determine the contact location and pressure distribution from the color change of the amorphous sugar layer.

Hereinafter, the present invention will be described in more detail with reference to Examples, but the present invention is not limited to these Examples.

[Example 1] Principle of measuring eyelid pressure In the production and inspection of scraped surfaces, a dark paint called blue paint or Komeitan is applied to the contact surface, and the members are rubbed against each other. The distribution is visually confirmed. Applying this principle, when a film-coated contact lens is attached as shown in Fig. 1 and blinking is performed, scratch marks are generated on the film in response to mechanical contact of the eyelids, and the contact location and pressure distribution are adjusted to the film thickness. It can be regarded as a change in color density. Since the movement of the eyelids is in the vertical direction, it is important to keep the lens from rotating, but this can be solved by using the toric lens (thick bottom, maintaining posture by the action of the weight) used in astigmatism lenses. It is possible (Naoki Iwasaki, New Ophthalmology, 32, 9, (2015), 1299-1300.).

The requirements for the coating material are 1) removal of the material and elution into tears within an appropriate number of blinks or wearing time, and 2) good biocompatibility and good coloring. .. Therefore, as a preliminary survey, a thin film was prepared from food materials such as agar, gelatin, starch, and sucrose, and scratch marks were observed by reciprocating scraping motion with physiological saline. As a result, the former three have a blinking speed (10 to 15 cm / s) (Antonio AV Cruz, Denny M. Garcia, Carolina T. Pinto, Sheila P. Cechetti, The Ocular Surface, 9, 1, (2011). , 29-41.), The elastic deformation of the film itself did not cause any trace, and the film itself was destroyed by multiple frictions (Kentaro Takao, Fumi Yuuki, Takeshi Hatsawa, 2019 Academic Lecture Meeting of the Japan Society for Precision Engineering) Shu, G16 ,, Hamamatsu, (2019.9.4)). Although the latter had difficulty in handling the sample, good scratch marks were generated. Therefore, in this example, it was decided to evaluate using a test piece obtained by forming a thin film of sucrose.

[Example 2] Manufacture of a scraping tester In order to understand the basic characteristics related to the formation of scratches on a sucrose film, a load-adjustable indenter is reciprocated on a flat sucrose test piece as shown in Fig. 2. Measure the removal depth Δt. As the test parameters, the number of reciprocations N, the indenter pressure P, and the indenter speed V can be considered, and a testing machine was devised to realize these. As the actuator for reciprocating motion, a small air cylinder was used in order to realize the blinking speed in a small stroke. In addition, the indenter has a structure in which the contact pressure can be adjusted according to the number of disk weights mounted by supporting a cylinder that can apply a uniform load on the bottom surface with a round bar and providing a holder at the top. Figure 3 shows the main structure of the scraping tester.

Since physiological saline is used as a substitute for tears in the abrasion test, stainless steel (SUS440) and aluminum (A5052) were used as the main members from the viewpoint of rust prevention. In order to reduce the weight of the holder, the holder is made of photo-curing resin by a 3D printer (Photon, Anycubic), and the lower diameter of the indenter is 10 mm. A small pneumatic cylinder (PDA 10 x 45, made by Koganei) with a cylinder diameter of 10 mm and a stroke of 45 mm is used for the air cylinder, and a speed controller (AS1301F, made by SMC) is metered out for speed adjustment. Connected with. Cylinder control was performed by a 4-port solenoid valve (VJ3130, manufactured by SMC), and the valve opening / closing timing was controlled by creating a special sketch from Arduino Uno. The supply pressure was 0.27 MPa, and when the cylinder speed at this time was measured with an optical speed measuring device (Bee Spi, manufactured by V Yagami), it was confirmed that reciprocating motion was possible at a speed of 5 to 160 cm / s. Figure 4 shows the appearance of the scraping tester manufactured based on the above.

The indenter pressure was calibrated with a digital scale (MUHUA, MH-600S6) with a resolution of 0.01 g using a metal disk whose mass can be set in steps of about 5 g as a weight. From this, it was confirmed that the relationship between the number of weights n and the indenter pressure P as shown in Table 1 was obtained, and that the target of 10 to 30 mmHg was satisfied. In addition, the load fluctuation during cylinder operation was about ± 9.8 × 10 ^-3 N (1 gf), which was 0.93 mmHg when converted to probe pressure, and it was confirmed that it could withstand use within the set pressure range.

[Example 3] Preparation of sucrose film test piece Since the purpose of this example is to grasp the reduction characteristics due to scratching of the sucrose film, no lenticular processing or dye addition is performed, and sucrose melted in a metal mold is poured to smooth the surface. The thick film-like material finished in 1 was used as a test piece. Figure 5 shows the manufacturing process. (A) Pour the molten sucrose material into an aluminum mold, and (c) press it with a molding plate to solidify it while it is fluid. After cooling, (d) the plate is peeled off, and (e) burrs are removed to complete the test piece.

The aluminum formwork was 70x30x10mm (A5052), and was carved to a depth of 1mm with a φ5mm milling blade, leaving 0.8mm around. As a result of experimental examination of the composition of sucrose material, 5 cc of ultrapure water cooled at 5 ° C was added to 1.5 g of sugar for cooking (manufactured by Dainippon Meiji Sugar Co., Ltd.) and heated in a 500 W microwave oven for 100 s. Was used. Since the material immediately after melting has fluidity at a temperature close to 180 ° C., it was immediately poured into a mold (room temperature). The pressure plate for flat molding is made by attaching heat-resistant PTFE tape (NITOFLON (registered trademark) No.903UL, manufactured by Nitto Denko) to a polished stainless steel plate (80x40xt3) from the viewpoint of ensuring ease of peeling from sucrose and sample flatness. It was molded with a 5 kg weight placed on it. After deburring, the surface was stored for 24 hours in a closed container containing silica gel so that the surface could be sufficiently solidified and dried. Figure 6 shows the formwork, molded plate, and completed test piece.

In order to confirm the flatness of the test piece, a stylus type surface shape measuring device (Dektak 150, manufactured by ULVAC; stylus radius 12.5 μm, stylus pressure 29.4 mN (≈3 mgf)) is used in the transverse direction between the central part and ± 10 mm. As a result of measurement, R _y = 10 μm was obtained, and it was confirmed that the sample had sufficient smoothness as a scraping test sample.

[Example 4] Experimental results using a scraping tester In the scraping test of a sucrose film, three types of experiments were conducted to evaluate the dependence of the removal depth Δt on the number of reciprocations N, the indenter pressure P, and the indenter velocity V. As a lubricant between the indenter and the test piece, 0.15 mL of phosphate buffered saline (PBS (-), manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.), which has a similar composition to tears, was added dropwise immediately before the experiment. This amount is the maximum of 3 drops for the usual amount of eye drops, and it was experimentally determined not to cause stick slip within the reciprocating range of the indenter. After the scraping test, a wipe (BEMCOT Clean Wipe P, manufactured by Asahi Kasei) was used to absorb moisture, and the mixture was dried in a closed container containing silica gel for 24 hours as in the case of preparation. After that, the central part was measured at three points by Dektak, and the average value was taken as the removal depth. Figure 7 shows the state of the scraping test and the measurement position.

[Example 4-1] Sample removal characteristics based on the number of reciprocations The number of reciprocations N is fixed at 5, 10, 15, 20, 40, 60, and 80 times at an indenter pressure P = 13.5 mmHg (1 weight). The scraping test was performed twice at V = 12.7 cm / s, which is close to the average blink speed. An example of the measurement result is shown in FIG. A dent was observed in the scraped portion, indicating that the sucrose material was removed by the reciprocating motion of the indenter. FIG. 9 shows a graph summarizing the relationship between the average value of the amount of decrease Δt and the number of round trips N based on such individual data. A clear linear relationship was observed between the number of round trips and the amount of material removed, indicating the possibility of obtaining a film thickness distribution proportional to the number of blinks. The approximate curve does not pass through the origin, but this causes the surface of the test piece outside the indenter passage to elute with pseudo-tear fluid (Fig. 8; inclined parts of y <5 mm and y> 20 mm), resulting in a certain amount of offset. It is thought that it was a fold.

[Example 4-2] Sample removal characteristics by indenter pressure When the number of reciprocations N is fixed at 20 and the indenter pressure P is changed according to the number of weights as in the above-mentioned example, the experimental result for the amount of decrease Δt. Is shown in FIG. Good linearity was observed in the eyelid pressure range of 10 to 30 mmHg, and a pressure sensitivity of 1.3 μm / mmHg was obtained. From this, it became clear that the film thickness also changed with pressure, demonstrating the measurable pressure distribution.

[Example 4-3] Sample removal characteristics by indenter speed In order to investigate the relationship between the blinking speed V and the amount of decrease Δt, P = 13.5 mmHg, N = 20 times was fixed, and the reciprocating speed was 6, 12, 18, 24. A scraping test was performed by changing to cm / s. The result is shown in FIG. As the speed increased, the amount of decrease tended to decrease at an accelerating rate. As shown in Fig. 12, tears are pushed between the indenter and the surface of the test piece by dynamic pressure, and lift L proportional to the square of the velocity V acts on the indenter to lower the contact pressure and tears due to floating. It is considered that this is because the thickness of the liquid layer has increased and the peeling action of the sucrose film has weakened. Therefore, it was suggested that the amount of decrease in film thickness was larger and the sensitivity was increased in the low-speed region of slow blinking.

[Example 4-4] Estimated thickness of sucrose coat required for eyelid pressure measurement As a standard measurement state of eyelid pressure by this method, average blink speed (10 to 15 cm / s), 20 blinks. Assuming an eyelid pressure of 100 to 130 mmHg, only the corresponding parameter parts were extracted from the experiments of the above-mentioned examples, and summarized as the required amount T of the sucrose coat film thickness is shown in FIG.

From this, it was shown that in the normal eyelid pressure range (<30 mmHg), if T> 130 μm, the change in pressure can be regarded as a film thickness decrease, and the sensitivity is 1.29 mmHg / μm.

Table 2 shows the required coating thickness T for the number of blinks obtained from the regression line in FIG. 11, which can be used as a guide for the film thickness coating required for actual measurement. can.

From the results of a series of experiments, it was confirmed that the sucrose film thickness required to obtain scratches by blinking about 20 times with normal eyelid pressure is a hundred and several tens of μm, which is a thickness that can be coated on contact lenses. Was done.

Since the present invention relates to an eyelid pressure measuring device, it can be used in an industrial field for manufacturing such a device.

Claims (4)

An eyelid pressure measuring device provided with a corneal mounting member that can be mounted on the cornea and an amorphous saccharide layer. 1) The corneal mounting member can contact the cornea and cover the cornea, and 2) the cornea. The mounting member is provided with a weight for preventing rotation on the cornea, and 3) the amorphous saccharide layer is provided on the surface of the corneal mounting member. Pressure measuring device. The eyelid pressure measuring device according to claim 1, wherein the amorphous saccharide layer contains a food pigment. The eyelid pressure measuring device according to claim 1 or 2, wherein the amorphous saccharide layer is an amorphous sucrose layer. The eyelid pressure measuring device according to any one of claims 1 to 3, wherein the thickness of the amorphous sugar layer is 100 to 200 μm.

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