A standard lens for testing contact lens oxygen permeability test instruments

Abstract

The present invention relates to a contact lens oxygen permeability coefficient standard lens for testing a contact lens oxygen permeability test instrument, and belongs to the field of ophthalmic optical metrology technology and instruments. The purpose of the present invention is to solve the metrological problem that the existing contact lens oxygen permeability test instrument cannot be calibrated, inspected and effectively traced. The contact lens oxygen permeability coefficient standard lens is composed of a series of spherical standard lenses and plane standard lenses with different oxygen permeability coefficient Dk values, and is used to test the indication error of polarographic and coulometric contact lens oxygen permeability test instruments; the standard lens has a circular shape, the front and rear surfaces of the spherical standard lens are both spherical and coaxial and concentric, and the front and rear surfaces of the plane standard lens are both plane and coaxial and concentric. The standard lens can be used for the precise inspection of the indication error of the contact lens oxygen permeability test instrument based on the polarographic and coulometric measurement principles, thereby ensuring that the oxygen permeability and oxygen permeability coefficient measurement results given by such instruments are accurate and reliable.

Description

Technical Field

[0001] The invention relates to a contact lens oxygen permeability coefficient standard lens used for testing a contact lens oxygen permeability testing instrument, and belongs to the field of ophthalmic optical metrology technology and instruments. Background Art

[0002] In 2016, my country's first white paper on systematic research on visual health, "National Visual Health", was released. The white paper shows that among people over the age of 5 in my country, one in three people is myopic, and the age of onset is significantly earlier. The younger age of myopia is not as simple as "wearing an extra pair of glasses". The occurrence and harm of myopia are irreversible. High myopia is prone to various fundus lesions, causing serious permanent visual function damage, and even blindness in severe cases, which is irreversible.

[0003] If myopia trends are detected, intervention treatment should be carried out in advance. Once myopia is confirmed, myopia correction should be carried out. In ophthalmic clinical practice, there are usually three methods for myopia correction: frame glasses, contact lenses and refractive surgery. The three methods have their own characteristics and benefit different groups. As people's requirements for visual quality, beauty and comfort continue to increase, the contact lens fitting rate has increased rapidly. Contact lenses are a type of ophthalmic lenses that are directly attached to the surface of the human cornea. Compared with frame glasses, they have the characteristics of beautiful wearing, wide field of vision, and close-to-real images. They are not only widely used in the correction and improvement of refractive errors such as myopia, hyperopia, and astigmatism, but also play a special role in controlling the development of myopia and astigmatism in adolescents and treating special ophthalmic diseases.

[0004] Since contact lenses are attached to the front surface of the human cornea through the tear layer, and corneal epithelial cells are a type of cell with extremely active metabolism and high oxygen supply requirements, only when there is sufficient oxygen supply can the cornea maintain a stable hydration state and ensure corneal transparency. Therefore, contact lenses should have a certain oxygen permeability to maintain normal ocular physiological circulation. In recent years, with the substantial increase in the market share of contact lenses and the rapid development of new ophthalmic medical biomaterials, research on the properties of contact lens materials has received more and more attention, especially the research on the oxygen permeability of contact lens materials, because it is directly related to the comfort of lens wearing and the physiological health and safety of the eyes.

[0005] At present, the test instruments used to measure the oxygen permeability of contact lenses at home and abroad are mainly based on two principles: polarography and coulometric method. The polarographic contact lens oxygen permeability test instrument mainly uses a polarographic probe and two electrodes, anode and cathode. After oxygen molecules pass through the contact lens, they contact the central electrode (cathode) and are instantly converted into 4 hydrogen ions to form a current. The magnitude of the current is proportional to the number of oxygen molecules that pass through. The oxygen permeability of the contact lens under test is obtained by measuring the generated current, and thus the oxygen permeability coefficient of the contact lens material is obtained. The coulometric contact lens oxygen permeability test instrument mainly uses a coulometric sensor to measure the amount of oxygen passing through the contact lens, generating a current proportional to the oxygen concentration flowing through the coulometric sensor. The oxygen permeability coefficient of the contact lens material under test is obtained by measuring the magnitude of the current. The polarographic method can measure not only soft hydrophilic contact lenses, but also hard gas permeable contact lenses, and has a wide range of applications. The coulometric method is mainly used for the oxygen permeability measurement of hard gas permeable contact lenses and non-hydrogel elastic contact lenses, and is particularly suitable for measuring lenses with an oxygen permeability coefficient greater than 145 Dk units. The two types of instruments have different measurement principles and slightly different scopes of application, but they are both widely used in contact lens production and R&D companies, manufacturing companies, metrology quality inspection, registration inspection and other industries and departments. The quality is crucial and directly related to the evaluation of the oxygen permeability performance of contact lens materials and the clinical application of contact lenses. There is currently no unified standard in the industry for the metrological calibration inspection of polarographic and coulometric contact lens oxygen permeability test instruments. The accuracy of the contact lens oxygen permeability and material oxygen permeability coefficient marked by the manufacturer cannot be evaluated, and the quality varies. With the increasing acceptance of contact lenses, whether from the perspective of standardizing the product quality and metrological supervision of contact lenses, or from the perspective of effective fitting, controlling myopia, and protecting consumers' vision health, it is urgent to solve the metrological calibration inspection and value traceability of contact lens oxygen permeability test instruments such as polarographic and coulometric methods, so as to solve the practical problem of accurate measurement of the oxygen permeability coefficient of contact lens materials. Therefore, the development and design of a contact lens oxygen permeability coefficient standard lens is an important means to evaluate the accuracy of the parameters of the contact lens oxygen permeability test instrument. Summary of the invention

[0006] In order to solve the metrological problem that existing contact lens oxygen permeability test instruments cannot be calibrated, inspected and effectively traced, the purpose of the present invention is to provide a standard lens for inspecting contact lens oxygen permeability test instruments, which can be used for accurately inspecting the indication error of contact lens oxygen permeability test instruments based on polarography and coulometric measurement principles, thereby ensuring that the oxygen permeability and oxygen permeability coefficient measurement results given by such instruments are accurate and reliable.

[0007] The purpose of the present invention is achieved through the following technical solutions.

[0008] The invention discloses a standard lens for testing a contact lens oxygen permeability tester, which is composed of a series of spherical standard lenses and plane standard lenses with different oxygen permeability coefficient Dk values ​​and is used for testing the indication error of polarographic and coulometric contact lens oxygen permeability testers.

[0009] The standard lens has a circular shape, the front and rear surfaces of the spherical standard lens are both spherical and coaxial and concentric, and the front and rear surfaces of the plane standard lens are both plane and coaxial and concentric.

[0010] A standard lens for testing a polarographic contact lens oxygen permeability tester is composed of a series of spherical standard lenses or plane standard lenses with different oxygen permeability coefficient Dk values. The radius of curvature of the rear surface of the standard lens is the same as the radius of curvature of the cathode surface of the polarographic probe. Under the premise of ensuring that the measurement range of the polarographic contact lens oxygen permeability tester is covered, the center thickness interval of the standard lens is arbitrarily determined. The center thickness of the standard lens is determined by increasing or decreasing the center thickness interval of the series of spherical standard lenses or plane standard lenses of each oxygen permeability coefficient by integer multiples. Finally, the front surface curvature radius of the standard lens is determined according to the coaxial and concentric principle.

[0011] A standard lens for testing a coulometric contact lens oxygen permeability tester is composed of a series of plane standard lenses with different oxygen permeability coefficient Dk values. The plane standard lens is circular in shape, and the front and rear surfaces are both plane and coaxial and concentric. Under the premise of ensuring that the measurement range of the coulometric contact lens oxygen permeability tester is covered, the center thickness of each oxygen permeability coefficient standard lens is arbitrarily determined.

[0012] Inspection process:

[0013] When checking the oxygen permeability coefficient indication error of the polarographic contact lens oxygen permeability tester with a flat surface of the polarographic probe cathode, a flat standard lens should be used. First, take two flat standard lenses at random, clamp a piece of aluminum foil between the two flat standard lenses, and stick them tightly to the polarographic probe anode to form a dark current test unit to ensure that no oxygen enters the polarographic probe cathode through the edge, then place the dark current test unit in a constant temperature and humidity chamber, set the temperature to 35°C, and the relative humidity is not less than 98%. According to the operating instructions of the polarographic contact lens oxygen permeability tester, measure the dark current of the polarographic probe, and record the dark current measurement results after the current reading is stable. Take out the dark current test unit, place a filter paper on the surface of the polarographic probe, select a flat standard lens, press it tightly against the surface of the polarographic electrode cathode with the filter paper, and place it in the above-mentioned constant temperature and humidity chamber, measure the current in this state according to the operating instructions of the polarographic contact lens oxygen permeability tester, and record the current measurement results after the current reading is stable. According to the formula, the primary oxygen permeability of the measured flat standard lens can be calculated. Finally, the oxygen permeability coefficient of the plane standard lens under test is obtained by correcting the edge effect and the boundary layer effect. By comparing this value with the standard value of the oxygen permeability coefficient of the plane standard lens, the oxygen permeability coefficient indication error of the polarographic contact lens oxygen permeability test instrument with a plane cathode surface of the polarographic probe can be obtained.

[0014] When checking the oxygen permeability coefficient indication error of the polarographic contact lens oxygen permeability tester with a spherical surface on the cathode surface of the polarographic probe, a spherical standard lens should be used. First, take two spherical standard lenses at random, clamp a piece of aluminum foil between the two spherical standard lenses, and stick them tightly to the anode of the polarographic probe to form a dark current test unit to ensure that no oxygen enters the cathode of the polarographic probe through the edge. Then place the dark current test unit in a constant temperature and humidity chamber, set the temperature to 35°C, and the relative humidity to not less than 98%. According to the operating instructions of the polarographic contact lens oxygen permeability tester, measure the dark current of the polarographic probe, and record the dark current measurement results after the current reading stabilizes. Take out the dark current test unit, place a filter paper on the surface of the polarographic probe, select a spherical standard lens, press it against the filter paper and the cathode surface of the polarographic electrode, and place it in the above-mentioned constant temperature and humidity chamber, measure the current in this state according to the operating instructions of the polarographic contact lens oxygen permeability tester, and record the current measurement results after the current reading stabilizes. According to the formula, the primary oxygen permeability of the spherical standard lens under test can be calculated. Finally, the oxygen permeability coefficient of the tested spherical standard lens is obtained by correcting the edge effect and the boundary layer effect. By comparing this value with the standard value of the oxygen permeability coefficient of the spherical standard lens, the oxygen permeability coefficient indication error of the polarographic contact lens oxygen permeability tester with a spherical cathode surface of the polarographic probe can be obtained.

[0015] When checking the oxygen permeability coefficient indication error of the coulometric contact lens oxygen permeability tester, a plane standard lens should be used. First, take any plane standard lens and seal it in the contact lens test cavity of the coulometric contact lens oxygen permeability tester with sealing grease. Set the temperature to 35°C and the relative humidity to 0%. Then measure it according to the operating instructions of the coulometric contact lens oxygen permeability tester. Substitute the measured oxygen flow rate into the formula for calculation to obtain the oxygen permeability coefficient of the measured plane standard lens. Compare this value with the standard value of the oxygen permeability coefficient of the plane standard lens to obtain the oxygen permeability coefficient indication error of the coulometric contact lens oxygen permeability tester.

[0016] The front and back surfaces of the standard lens are finely polished, and the lens parameters are accurately processed by high-precision measurement of parameters such as diameter, radius of curvature and center thickness.

[0017] The material of the standard lens is a high molecular polymer and should be uniform and stable.

[0018] Beneficial effects:

[0019] 1. The standard lens for testing the oxygen permeability test instrument of contact lenses of the present invention can ensure that the radial thickness of the lens at different points is the same and equal to the thickness of the geometric center by adopting the coaxial and concentric design principle, which is conducive to accurately correcting the edge effect and the boundary layer effect and improving the inspection accuracy. The spherical standard lens and the plane standard lens with different oxygen permeability coefficients and different center thicknesses designed to be close to the structure of the contact lens product can realize the inspection of the oxygen permeability coefficient indication error of the contact lens oxygen permeability test instrument within the range of (0-180)Dk. Among them, the plane standard lens is suitable for the indication error inspection and calibration curve fitting of the coulometric contact lens oxygen permeability test instrument and the polarographic contact lens oxygen permeability test instrument with a flat polarographic probe, and the spherical standard lens is suitable for the indication error inspection and calibration curve fitting of the polarographic contact lens oxygen permeability test instrument with a spherical polarographic probe.

[0020] 2. The standard lens for testing the oxygen permeability tester of contact lenses of the present invention is composed of a series of spherical standard lenses and plane standard lenses with different oxygen permeability coefficient Dk values. Through the quality control of various lens structural parameters, the accurate processing and setting of multiple parameters such as the diameter, the back surface curvature radius, the front surface curvature radius and the center thickness of the standard lens can be guaranteed. The structural design fully considers the influence of the edge effect and the boundary layer effect in the calibration and inspection process of the polarographic contact lens oxygen permeability tester, as well as the unique structural characteristics of the polarographic probe cathode of the polarographic contact lens oxygen permeability tester and the contact lens test cavity of the coulometric contact lens oxygen permeability tester, and has the advantages of simple structure, convenient operation and wide application range. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 A schematic diagram of a plane standard lens for testing the oxygen permeability of contact lenses of the present invention;

[0022] Figure 2 It is a schematic diagram of a spherical standard lens used for testing the oxygen permeability of contact lenses of the present invention;

[0023] Figure 3 Schematic diagram of boundary layer effect correction.

[0024] Among them, 1- flat standard lens, 2- spherical standard lens, 3- front surface, 4- back surface. DETAILED DESCRIPTION

[0025] The present invention will be further described below in conjunction with the accompanying drawings and embodiments.

[0026] The standard lens for testing a contact lens oxygen permeability tester of the present invention is composed of a series of spherical standard lenses and plane standard lenses with different oxygen permeability coefficient Dk values, and can be used to test the oxygen permeability coefficient indication error of polarographic and coulometric contact lens oxygen permeability testers, and provide a calibration curve.

[0027] The present invention provides a standard lens for testing a contact lens oxygen permeability tester, which may include:

[0028] 1. Flat standard lens, such as Figure 1 As shown. The standard lens is a plane lens with a circular shape. The front and back surfaces are both plane and coaxial. It is composed of at least 5 series of plane standard lenses with different oxygen permeability coefficients. The oxygen permeability coefficient range is (0-180) Dk, covering the different oxygen permeability coefficient ranges of low (0-50) Dk, medium (50-100) Dk, and high (100-180) Dk, which meets the inspection range of polarographic and coulometric contact lens oxygen permeability test instruments. The plane standard lens of each oxygen permeability coefficient is composed of plane lenses with the same outer diameter but different center thickness. The center thickness is designed to increase at equal intervals, which are: 0.10mm, 0.15mm, 0.20mm, 0.25mm, 0.30mm, 0.35mm, and 0.40mm. During the processing, the center thickness of the plane standard lens is strictly controlled, and the processing tolerance is ±0.01mm. The center thickness and diameter are measured using a high-precision thickness gauge and a digital caliper to ensure accurate processing parameters. The plane standard lens can meet the oxygen permeability coefficient indication error inspection of a coulometric contact lens oxygen permeability test instrument and a polarographic contact lens oxygen permeability test instrument with a plane polarographic probe.

[0029] The specific working process is as follows:

[0030] 1) When checking the oxygen permeability coefficient indication error of the polarographic contact lens oxygen permeability tester with a flat surface on the cathode of the polarographic probe, a flat standard lens should be used. First, take any two flat standard lenses, sandwich a piece of aluminum foil between the two flat standard lenses, and stick them tightly to the anode of the polarographic probe to form a dark current test unit to ensure that no oxygen enters the cathode of the polarographic probe through the edge, then place the dark current test unit in a constant temperature and humidity chamber, set the temperature to 35°C, and the relative humidity to not less than 98%, measure the dark current of the polarographic probe according to the operating instructions of the polarographic contact lens oxygen permeability tester, and record the dark current measurement results after the current reading stabilizes. Take out the dark current test unit, place a piece of filter paper on the surface of the polarographic probe, select a flat standard lens, press it against the cathode surface of the polarographic electrode in contact with the filter paper, and place it in the above-mentioned constant temperature and humidity chamber, measure the current in this state according to the operating instructions of the polarographic contact lens oxygen permeability tester, and record the current measurement results after the current reading stabilizes. Substitute the measured current into formula (1) to calculate the primary oxygen permeability of the measured plane standard lens.

[0031]

[0032] Where:

[0033] ——Primary oxygen permeability of the lens under test, cm 3 / (cm 2 ·s·hPa);

[0034] p A ——The difference between atmospheric pressure and water vapor pressure multiplied by 0.209 (the percentage of oxygen content in the atmosphere), hPa;

[0035] A——Surface area of ​​the cathode of the polarographic probe, cm 2 ;

[0036] I——measured current value, A;

[0037] I d ——Dark current value of polarographic probe, A;

[0038] C——constant 5.084×10 -2 cm 3 / (A·s);

[0039] H——chord radius of the cathode of the polarographic probe, cm;

[0040] Since the polarographic contact lens oxygen permeability tester is affected by edge effect and boundary layer effect when measuring the oxygen permeability of contact lenses, the primary oxygen permeability obtained must be corrected. When a flat probe is used to measure a flat standard lens, the edge effect correction is shown in formula (2).

[0041]

[0042] Where:

[0043] Dk——oxygen permeability coefficient of the lens under test, 10 -11 cm 3 cm / (cm 2 ·s·hPa);

[0044] D——polarographic probe cathode diameter, cm;

[0045] t——the center thickness of the lens being tested, cm;

[0046] i∑——the sum of n measurements, each with thickness (t i ) and the reciprocal of oxygen permeability

[0047] For each oxygen permeability coefficient, seven plane standard lenses with different center thicknesses are designed. The primary oxygen permeability Dk / t value of the plane standard lens of each thickness can be calculated by measuring the current and substituting it into formula (1). Then, the reciprocal t / Dk value and the thickness t are substituted into formula (2) to obtain the t / Dk value of each plane standard lens after edge effect correction.

[0048] Finally, for the seven plane standard lenses of each oxygen permeability coefficient, the edge effect-corrected t / Dk values ​​obtained from plane standard lenses of different thicknesses were plotted against thickness t to form a curve. The slope of the regression line obtained by least squares fitting is the reciprocal of the oxygen permeability coefficient after correcting the boundary layer effect, i.e., 1 / Dk. The Dk value obtained at this time is the final value after correcting the edge effect and boundary layer effect. By comparing this value with the standard value of the oxygen permeability coefficient of the plane standard lens, the oxygen permeability coefficient indication error of the polarographic contact lens oxygen permeability tester with a plane cathode surface of the polarographic probe can be obtained.

[0049] 2) When checking the error of the oxygen permeability coefficient indication of the coulometric contact lens oxygen permeability tester, a plane standard lens should be used. First, take any plane standard lens and seal it in the contact lens test cavity of the coulometric contact lens oxygen permeability tester with sealing grease. The temperature is set to 35°C and the relative humidity is set to 0%. Then, measure it according to the operating instructions of the coulometric contact lens oxygen permeability tester. Substitute the measured oxygen flow rate into formula (3) to calculate the oxygen permeability coefficient of the plane standard lens being tested.

[0050]

[0051] Where:

[0052] A——Test area of ​​the lens under test, cm 2 ;

[0053] ——Oxygen flow rate through the Coulometric sensor, cm 3 / s.

[0054] The meanings of other parameters are the same as those in formulas (1) and (2).

[0055] When a plane standard lens is used to test the coulometric contact lens oxygen permeability tester, the plane standard lens is encapsulated in the contact lens test cavity of the coulometric contact lens oxygen permeability tester. Since the area of ​​oxygen passing through the front and back surfaces of the plane standard lens is the same, the edge effect can be ignored. At the same time, the test is carried out under 0% RH conditions. There is no aqueous solution on the front and back surfaces of the plane standard lens, and there is no boundary layer, so the boundary layer effect does not need to be corrected here. Therefore, when using a plane standard lens to test the oxygen permeability coefficient indication error of the coulometric contact lens oxygen permeability tester, for each plane standard lens of oxygen permeability coefficient, only one plane standard lens with a center thickness needs to be selected for testing. The oxygen permeability coefficient measurement value obtained is compared with the oxygen permeability coefficient standard value of the plane standard lens to obtain the oxygen permeability coefficient indication error of the coulometric contact lens oxygen permeability tester.

[0056] 2. Spherical standard lens, such as Figure 2 As shown. The standard lens is a spherical lens with a circular shape. The front and back surfaces are both spherical and coaxial. It is composed of at least 5 series of spherical standard lenses with different oxygen permeability coefficients. The oxygen permeability coefficient range is (0-180) Dk, covering different oxygen permeability ranges of low (0-50) Dk, medium (50-100) Dk, and high (100-180) Dk, which meets the inspection range of the polarographic contact lens oxygen permeability test instrument. The spherical standard lens of each oxygen permeability coefficient is composed of spherical lenses with the same outer diameter and the same back surface curvature radius, but different front surface curvature radius and different center thickness. The center thickness is designed to increase at equal intervals, which are: 0.10mm, 0.15mm, 0.20mm, 0.25mm, 0.30mm, 0.35mm, 0.40mm. The radius of curvature of the rear surface is the same as that of the cathode surface of the polarographic probe. The radius of curvature of the front surface is determined according to the coaxial and concentric design principle to ensure that the radial thickness of the spherical standard lens at each point is the same as the center thickness. During the processing, the radius of curvature of the front and rear surfaces, the center thickness and the radial thickness of the spherical standard lens are strictly controlled. The tolerance of the curvature radius processing is ±0.02mm, and the tolerance of the thickness processing is ±0.01mm. The center thickness, radius of curvature and diameter are measured using a high-precision thickness gauge, a curvature radius tester and a digital caliper to ensure accurate parameter processing. The spherical standard lens can meet the oxygen permeability coefficient indication error test of the polarographic contact lens oxygen permeability tester with a spherical polarographic probe.

[0057] The specific working process is as follows:

[0058] When checking the oxygen permeability coefficient indication error of the polarographic contact lens oxygen permeability tester with a spherical surface on the cathode surface of the polarographic probe, a spherical standard lens should be used. First, take two spherical standard lenses at random, clamp a piece of aluminum foil between the two spherical standard lenses, and stick them tightly to the anode of the polarographic probe to form a dark current test unit to ensure that no oxygen enters the cathode of the polarographic probe through the edge, and then place the dark current test unit in a constant temperature and humidity chamber, set the temperature to 35°C, and the relative humidity is not less than 98%. According to the operating instructions of the polarographic contact lens oxygen permeability tester, the dark current of the polarographic probe is measured, and the dark current measurement results are recorded after the current reading is stable. Take out the dark current test unit, place a filter paper on the surface of the polarographic probe, select a spherical standard lens, press it tightly against the cathode surface of the polarographic electrode in contact with the filter paper, and place it in the above-mentioned constant temperature and humidity chamber, measure the current in this state according to the operating instructions of the polarographic contact lens oxygen permeability tester, and record the current measurement results after the current reading is stable. Substitute the measured current into formula (4) to calculate the primary oxygen permeability of the measured spherical standard lens.

[0059]

[0060] Where:

[0061] r——radius of curvature of the cathode surface of the polarographic probe, cm;

[0062] The meanings of other parameters are the same as those in formulas (1) and (2).

[0063] Since the polarographic contact lens oxygen permeability tester measures the contact lens oxygen permeability coefficient with the influence of edge effect and boundary layer effect, the primary oxygen permeability obtained must be corrected. When a spherical probe is used to measure a spherical standard lens, the edge effect correction is shown in formula (5), and the meanings of the various parameters are the same as those of formulas (1) and (2).

[0064]

[0065] For each oxygen permeable material, seven spherical standard lenses with different center thicknesses are designed. The spherical standard lenses of each thickness can be measured and substituted into formula (4) to calculate the primary oxygen permeability Dk / t value. Then, the reciprocal t / Dk value and the thickness t are substituted into formula (5) to obtain the t / Dk value of each spherical standard lens after edge effect correction.

[0066] Finally, for the seven spherical standard lenses of each oxygen permeability coefficient, the t / Dk values ​​after edge effect correction obtained by measuring spherical standard lenses of different thicknesses and the thickness t are plotted into a curve. The slope of the regression line obtained by least squares fitting is the reciprocal of the oxygen permeability coefficient after correcting the boundary layer effect, that is, 1 / Dk. The Dk value obtained at this time is the final value after correcting the edge effect and boundary layer effect. By comparing this value with the standard value of the oxygen permeability coefficient of the spherical standard lens, the oxygen permeability coefficient indication error of the polarographic contact lens oxygen permeability test instrument with a spherical cathode surface of the polarographic probe can be obtained.

[0067] Here, a polarographic contact lens oxygen permeability test instrument with a spherical cathode surface of a polarographic probe is taken as an example, and a spherical standard lens with a standard oxygen permeability coefficient of 11 Dk units is used to test it. The obtained current value, initial oxygen permeability t / Dk value and t / Dk value after edge effect correction are shown in Table 1 below.

[0068] Table 1 Test results

[0069]

[0070] The t / Dk value after edge effect correction is fitted by the least squares method to obtain the following: Figure 3 The curve and function expression shown.

[0071] From the fitting results, we can get that 1 / Dk after interface effect correction is 7.80×10 9 s cm 2 mmHg / (cm 3 cm), and thus the oxygen permeability coefficient of the tested spherical standard lens is 9.6×10 -11 cm 3 cm / (s cm 2 hPa), which is 9.6 Dk units (1 Dk unit = 10 -11 cm 3 cm / (s cm 2 hPa)). By comparing this value with the standard value of 11 Dk units of the oxygen permeability coefficient of the spherical standard lens, it can be obtained that the oxygen permeability coefficient indication error of the polarographic contact lens oxygen permeability test instrument with a spherical cathode surface of the polarographic probe at this point is -1.4 Dk units, and the relative indication error is 13%.

[0072] The specific implementation modes of the present invention are described above in conjunction with the accompanying drawings, but these descriptions cannot be understood as limiting the scope of the present invention. The protection scope of the present invention is defined by the attached claims, and any changes based on the claims are within the protection scope of the present invention.

Claims

1. A method for testing a polarographic contact lens oxygen permeability tester using a standard lens, characterized in that: Standard lenses are made of different oxygen permeability coefficients Dk It is composed of a series of spherical standard lenses or plane standard lenses with different values, and is used to check the indication error of polarographic contact lens oxygen permeability test instruments; The standard lens has a circular shape, the front and rear surfaces of the spherical standard lens are both spherical and coaxial and concentric, and the front and rear surfaces of the plane standard lens are both plane and coaxial and concentric; The standard lenses used to test the polarographic contact lens oxygen permeability test instrument are composed of lenses with different oxygen permeability coefficients. Dk The series of spherical standard lenses or plane standard lenses of different values ​​are composed; the radius of curvature of the rear surface of the standard lens is the same as the radius of curvature of the cathode surface of the polarographic probe. Under the premise of ensuring that the measuring range of the polarographic contact lens oxygen permeability test instrument is covered, the center thickness interval of the standard lens is determined arbitrarily. The center thickness of the series of spherical standard lenses or plane standard lenses of each oxygen permeability coefficient is determined by increasing or decreasing the center thickness interval by integer multiples. Finally, the front surface curvature radius of the standard lens is determined according to the coaxial and concentric principle. When checking the oxygen permeability coefficient indication error of the polarographic contact lens oxygen permeability tester with a flat surface of the polarographic probe cathode, a flat standard lens should be used; first, randomly select two flat standard lenses, sandwich a piece of aluminum foil between the two flat standard lenses, and stick them tightly to the polarographic probe anode to form a dark current test unit to ensure that no oxygen enters the polarographic probe cathode through the edge, and then place the dark current test unit in a constant temperature and humidity chamber, set the temperature to 35°C, and the relative humidity to not less than 98%, measure the dark current of the polarographic probe according to the operating instructions of the polarographic contact lens oxygen permeability tester, and record the dark current measurement results after the current readings stabilize; take out the dark current test unit , place a piece of filter paper on the surface of the polarographic probe, select a flat standard lens, press it tightly against the cathode surface of the polarographic electrode in contact with the filter paper, and place it in the above-mentioned constant temperature and humidity chamber, measure the current in this state according to the operating instructions of the polarographic contact lens oxygen permeability tester, and record the current measurement result after the current reading stabilizes; the primary oxygen permeability of the measured flat standard lens can be calculated according to the formula; finally, the oxygen permeability coefficient of the measured flat standard lens can be obtained by correcting the edge effect and the boundary layer effect; compare this value with the standard value of the oxygen permeability coefficient of the flat standard lens, and the oxygen permeability coefficient indication error of the polarographic contact lens oxygen permeability tester with a flat cathode surface of the polarographic probe can be obtained; When checking the oxygen permeability coefficient indication error of the polarographic contact lens oxygen permeability tester with a spherical surface on the cathode surface of the polarographic probe, a spherical standard lens should be used; first, randomly select two spherical standard lenses, sandwich a piece of aluminum foil between the two spherical standard lenses, and stick them tightly to the anode of the polarographic probe to form a dark current test unit to ensure that no oxygen enters the cathode of the polarographic probe through the edge, and then place the dark current test unit in a constant temperature and humidity chamber, set the temperature to 35°C, and the relative humidity to not less than 98%, measure the dark current of the polarographic probe according to the operating instructions of the polarographic contact lens oxygen permeability tester, and record the dark current measurement results after the current readings stabilize; take out the dark current test unit , place a piece of filter paper on the surface of the polarographic probe, select a spherical standard lens, press it tightly against the cathode surface of the polarographic electrode in contact with the filter paper, and place it in the above-mentioned constant temperature and humidity chamber, measure the current in this state according to the operating instructions of the polarographic contact lens oxygen permeability tester, and record the current measurement result after the current reading stabilizes; the primary oxygen permeability of the measured spherical standard lens can be calculated according to the formula; finally, the oxygen permeability coefficient of the measured spherical standard lens can be obtained by correcting the edge effect and the boundary layer effect; compare this value with the standard value of the oxygen permeability coefficient of the spherical standard lens, and the oxygen permeability coefficient indication error of the polarographic contact lens oxygen permeability tester with a spherical cathode surface of the polarographic probe can be obtained.

2. A method for testing a coulometric contact lens oxygen permeability tester using a standard lens, characterized in that: Standard lenses are made of different oxygen permeability coefficients Dk It is composed of a series of spherical standard lenses or plane standard lenses with different values, and is used to check the indication error of polarographic contact lens oxygen permeability test instruments; The standard lens has a circular shape, the front and rear surfaces of the spherical standard lens are both spherical and coaxial and concentric, and the front and rear surfaces of the plane standard lens are both plane and coaxial and concentric; The standard lenses used to test the coulometric contact lens oxygen permeability tester are composed of lenses with different oxygen permeability coefficients. Dk The plane standard lens is composed of a series of plane standard lenses with the same value; the plane standard lens is circular in shape, and the front and back surfaces are both plane and coaxial and concentric; on the premise of ensuring that the measurement range of the coulometric contact lens oxygen permeability test instrument is covered, the center thickness of each oxygen permeability coefficient standard lens is arbitrarily determined; When checking the indication error of the oxygen permeability coefficient of the coulometric contact lens oxygen permeability tester, a plane standard lens should be used; firstly, take any plane standard lens and seal it in the contact lens test cavity of the coulometric contact lens oxygen permeability tester with sealing grease, set the temperature to 35°C and the relative humidity to 0%, then measure it according to the operating instructions of the coulometric contact lens oxygen permeability tester, and substitute the measured oxygen flow rate into the formula for calculation to obtain the oxygen permeability coefficient of the measured plane standard lens; compare this value with the standard value of the oxygen permeability coefficient of the plane standard lens to obtain the indication error of the oxygen permeability coefficient of the coulometric contact lens oxygen permeability tester.

3. The method according to claim 1 or 2, characterized in that: The front and back surfaces of the standard lens are finely polished, and the lens parameters are accurately processed through high-precision measurement of the diameter, radius of curvature and center thickness.

4. The method according to claim 1 or 2, characterized in that: The material of standard lenses is high molecular polymer, which should be uniform and stable.

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