A refraction test card and a method of measuring the same

Abstract

The present application provides a refraction test card and a test method thereof. The test card comprises a target in a black background, and a partition unit in the center of the target, which visually separates the target. The test method comprises: judging whether the subject has astigmatism according to the clarity of the contrast between the target and the black background in the astigmatism test card; if the subject is determined to have astigmatism, the astigmatism axis direction is determined; judging whether the subject has hyperopia or myopia according to the clarity of the contrast between the target and the black background in the spherical power test card; and testing and calculating the spherical power and astigmatism power of the subject. The present application provides a simple refraction test tool and method to determine whether the subject has refractive error, the type of refractive error and the quantitative refractive error.

Description

TECHNICAL FIELD

[0001] The present invention relates to the field of optometry for refractive errors of the eye, and in particular to a refraction test card and a method of measuring the same. BACKGROUND

[0002] Refractive error is the failure of the eye to bring parallel rays of light to a focus on the retina. It includes hyperopia, myopia and astigmatism. All refractive error examinations require a complete set of instruments and a trained optometrist or ophthalmologist to perform the examination. The examination includes:

[0003] 1. Subjective examination

[0004] It can only approach but not completely offset the deviation caused by accommodation. Refractive error examination after mydriasis can theoretically offset the refractive error caused by accommodation, but the refractive power obtained by such an examination is not representative of the daily power, so the refractive power obtained can cause blurred vision in daily life.

[0005] (a) Preliminary analysis of refractive properties according to visual acuity examination (not quantitative)

[0006] (b) Pinhole and slit examination (a simple method to tell us whether visual acuity can be improved by removing refractive error, not quantitative)

[0007] (c) Astigmatism chart examination (only a rough estimate of astigmatism axis, not quantitative)

[0008] (d) Cross-cylinder and astigmatism corrector examination (complex steps, time-consuming, young subjects are easily confused, accuracy is affected by spherical power)

[0009] (e) Insertion test (tests spherical power but is affected by astigmatism)

[0010] (f) Cloud and fog method (helps to better approach the true spherical power)

[0011] (g) Red and green target simultaneous clarity method (avoids exceeding the true spherical power)

[0012] (h) Laser speckle pattern method (not universal, high equipment cost)

[0013] 2. Objective examination

[0014] (a) Direct ophthalmoscope examination (only knows the power of the glasses being worn at the time, does not know the latest power, and does not know whether the power of the glasses is accurate)

[0015] (b) keratometer (only the corneal curvature can be obtained to estimate the spherical power and astigmatism and the astigmatism axis caused by the asymmetry of the cornea, but the spherical power, astigmatism and astigmatism axis of the whole eyeball cannot be known.)

[0016] (c) autorefractor (can roughly estimate the spherical power, astigmatism and astigmatism axis. But because of the influence of involuntary accommodation of the measured person, it cannot be accurate, and often does not match the true power.)

[0017] (d) streak retinoscopy (usually used with lenses to achieve neutralization to estimate the approximate power. The spherical power, astigmatism and astigmatism axis obtained are estimates, and the phoropter and cross cylinder and astigmatism corrector refraction methods are needed to find the spherical power, astigmatism and astigmatism axis.)

[0018] (e) retinoscopy.

[0019] In addition, in ophthalmology, astigmatism is a manifestation of abnormal refraction of the eye, and most astigmatism is related to the curvature of the cornea. When parallel light enters the eye, because the refractive power of the eyeball is not equal on different meridians, the light on each meridian cannot be converged at a point (focal point), so the same object will form more than one object image that does not completely overlap, and a clear object image cannot be formed. This condition is called astigmatism.

[0020] Most clinical astigmatism is purely caused by asymmetry of the curvature of the cornea, but sometimes it is caused by eye lesions, especially anterior segment lesions, such as ptosis, conjunctival mass compression, corneal scab, pterygium, shape, position, opacity of the lens, etc.

[0021] Generally, the existing astigmatism examination usually adopts the following methods:

[0022] 1. Visual acuity test

[0023] Through distance visual acuity and near visual acuity tests, astigmatism can be found. Patients with severe astigmatism have poor distance visual acuity and near visual acuity.

[0024] 2. Astigmatism observation

[0025] The subjective examination of astigmatism eyes can be observed by astigmatism, and the relative clarity or blurred object image shape on the retina can preliminarily understand the astigmatism meridian of the examined eye.

[0026] The principle is based on the visual effect of multiple point connection:

[0027] The common fixed astigmatism chart (clock astigmatism chart) is composed of many radial lines. Based on the principle of multi-point series effect, the more points, the clearer the series. In the absence of astigmatism, each line has its own direction and is different from each other in direction, but the series density of points along the long axis of each line is the same, so the clarity of each line is the same, and no line is more prominent. When there is astigmatism, each line has its own direction and is different from each other, so the series density of points along the long axis of each line is not the same, at this time one or two lines look clearer and more obvious. Along the parallel direction of the line, the series is relatively more and closer, so the line looks clearer. The series that is rotated 90° relative to the long axis direction of the line is a relatively small series of points, so it is relatively blurred.

[0028] For example, both are tested by traditional clock astigmatism chart. Figure 1 And Figure 2 For example, both are tested by traditional clock astigmatism chart.

[0029] Figure 1 When there is no astigmatism, the line-shaped visual target arranged in a divergent manner looks about the same clear and concentrated in different direction axes.

[0030] Figure 2 When there is astigmatism, for example, the astigmatism axis is 90°, as the deviation from the 90° direction of the astigmatism axis becomes smaller, the line visual target becomes more concentrated and clearer. When the deviation from the direction of the astigmatism axis becomes larger, the line visual target becomes more diffuse and blurred.

[0031] Why is the vertical line visual target the clearest? Because each point on the line is gathered along the vertical direction of the line, and when many vertical focusing lines overlap, the observer sees a very clear vertical line. Once a correct astigmatism lens is used to correct the observer, the clarity of each line on Figure 2 is the same as Figure 1 .

[0032] 3. Retinal shadowing:

[0033] Specifically, any one of the following five situations indicates astigmatism: ① the reflection band is narrow and not uniform; ② the refraction of a pair of meridians is different; ③ the fundus reflection is irregular; ④ cutting; ⑤ the movement direction of the band-shaped light and the fundus reflection band is not consistent.

[0034] 4. Check the diopter:

[0035] (a) Objective refraction

[0036] Methods of astigmatism measurement include cylinder lens and sphere lens. The axis and degree of astigmatism can be determined. Astigmatism can be classified as mild (≤2.00D), moderate (2.25-4.00D), and severe (>4.00D). Astigmatism less than 1.00D is physiological.

[0037] (b) Subjective refraction

[0038] Subjective refraction is usually performed after objective refraction.

[0039] 5. Corneal astigmatism examination

[0040] This includes corneal curvature meter or corneal topography or quantitative corneal astigmatism examination.

[0041] 6. Fundus examination

[0042] The optic disc is usually oval-shaped. In cases of high astigmatism, the vertical margin of the optic disc can be seen, while the horizontal margin cannot be seen or vice versa. From the shape of the optic disc, the axis of astigmatism can be roughly understood.

[0043] The accuracy of the above methods of refractive error examination is affected by many factors, and there are the following shortcomings or deficiencies:

[0044] First, the person being tested must go to a hospital, clinic, optician, or other place and face a professional doctor or optometrist for refraction examination.

[0045] Second, the testing site needs to have sufficient and various refraction and optical lens instruments and equipment.

[0046] Third, the person being tested needs to have sufficient professional knowledge of optical refraction principles and skilled practical operation skills.

[0047] Fourth, the testing time is affected and limited by the daily life and office hours of the person being tested and the person being tested, because the round-trip traffic time is long, time-consuming and labor-intensive.

[0048] Fifth, the traditional computer automatic refraction instrument, because the distance between the eye and the target is very close, will cause significant near-source accommodation, resulting in inaccurate computer refraction results.

[0049] Sixth, the traditional lens insertion method requires the eye and the lens to be at a fixed close distance, which is often not strictly followed by the optometrist and the subject. At the same time, because the most appropriate spherical power lens is not known during the lens insertion method, the lens often needs to be changed during the test, which can easily cause the subject's eyes to unconsciously adjust. These can cause inaccurate test results. In addition, the test process is too complicated, and the subject, especially young children, cannot understand what they need to do to cooperate with the optometrist, so often inaccurate and large deviation test results are obtained. Many times in busy pediatric ophthalmology departments, testers will skip this step and directly use the degree of the computer automatic optometry instrument, causing greater errors.

[0050] Seventh, the existing astigmatism test process is complicated and requires professional guidance and objective testing in a special place, so it is relatively inconvenient to use. In addition, this method requires the subject to see the radial stripes relatively clearly after correcting part of the refractive error, so it is not suitable for testing without correcting refractive error.

[0051] Due to the above test methods and influencing factors, the test results of the same subject at different locations often have deviations. Even the same subject at the same location and by the same optometrist or ophthalmologist, but the test results on different dates have deviations.

[0052] The commonly used visual acuity charts in clinical practice are: international standard visual acuity chart, Landolt ring visual acuity chart, logarithmic visual acuity chart, digital visual acuity chart, English letter visual acuity chart and children's graphic visual acuity chart.

[0053] The commonly used astigmatism charts are: fixed astigmatism chart (clock astigmatism chart) and movable astigmatism chart (fan-shaped visual target, consisting of a fan-shaped radial scale and a rotatable disc. The disc has a set of perpendicular grid blocks and an inverted V-shaped visual target).

[0054] No matter what type of visual acuity chart and astigmatism chart, there is a problem of too many visual targets. Multiple visual targets can cause the subject to produce a dense effect when observing, thereby affecting the subject's judgment. At this time, the subject is easy to automatically adjust, causing the need for stronger spherical power lenses to obtain a clear image, so the spherical power is easily overestimated.

[0055] In the formal test environment, the subject is more difficult to relax, and is easy to produce unnecessary adjustment, thus causing false test results.

[0056] The lens insertion method requires frequent replacement or rotation of the lens, which can easily cause the subject's confusion and adjustment changes, resulting in test degree errors. SUMMARY

[0057] In view of the above, the present application provides a new refraction testing tool and method to overcome the inconvenience and subjective and experience bias of different optometrists in actual measurement of spherical power, astigmatism power and astigmatism axis.

[0058] The technical problem to be solved by the present application is to provide an innovative and simple optometry tool and method to find out whether the subject has refractive error, which type of refractive error and the quantitative refractive error.

[0059] To solve the above technical problem, the present application provides a refraction testing card, characterized in that it comprises a target in a black background, wherein the center position of the target comprises a partition unit, and the partition unit visually separates the target.

[0060] Preferably, the present application further provides a refraction testing card, characterized in that the target comprises a long strip target, and the color of the long strip target comprises any one of white and red.

[0061] Preferably, the present application further provides a refraction testing card, characterized in that the target comprises a cross-shaped target, and the color of the cross-shaped target comprises white.

[0062] Preferably, the present application further provides a refraction testing card, characterized in that the shape of the partition unit comprises any one of rectangular and circular.

[0063] Preferably, the present application further provides a refraction testing card, characterized in that the length of the target is 260mm±50mm, and the width is 5mm±2mm.

[0064] Preferably, the present application further provides a refraction testing card, characterized in that the width of the partition unit is less than or equal to 5mm, and the height ranges from 5mm±2mm.

[0065] Preferably, the present application further provides a refraction testing card, characterized in that the testing card comprises an astigmatism testing card and a spherical power testing card, wherein the astigmatism testing card comprises a white long strip target and a cross-shaped target, and the spherical power testing card comprises a red long strip target.

[0066] The present application further provides a measurement method using any one of the above refraction testing cards, characterized in that it comprises:

[0067] Step a: judging whether the subject has astigmatism according to the clarity of the contrast between the target and the black background in the astigmatism testing card observed by the subject;

[0068] Step b, if the subject is determined to have astigmatism, the astigmatism axis direction is measured, and if there is no astigmatism, step d is entered and the process is ended;

[0069] Step c, the subject is asked to observe the clarity of the contrast between the visual target and the black background in the spherical degree test card, and to determine whether the subject has myopia or hypermetropia;

[0070] Step d, the spherical degree of the subject is tested and calculated;

[0071] Step e, if there is astigmatism, the astigmatism degree of the subject is further tested and calculated.

[0072] Preferably, the present application further provides a measurement method, wherein the measurement of the astigmatism axis direction in step b comprises:

[0073] Step b1, the subject measures with one naked eye, rotates the astigmatism test card at a speed not higher than 12.5° / s, and obtains the direction of maximum clarity observed by the subject to the astigmatism test card;

[0074] Step b2, the maximum clarity direction ±90° is determined as the astigmatism axis direction.

[0075] Preferably, the present application further provides a measurement method, wherein step d further comprises:

[0076] Step d1, the subject moves to the direction of the spherical degree test card with one naked eye to measure the clearest distance d, and the focal length f:

[0077] f=d (1)

[0078] Step d2, according to the spherical degree D:

[0079] D=1 / f (2)

[0080] Obtain the first spherical degree D1;

[0081] Step d3, rotate the spherical degree test card by 90°, repeat steps d1-d2, and obtain the second spherical degree D2;

[0082] Step d4, the spherical degree D of the eyeball of the subject:

[0083] D=(D1+D2) / 2 (3)

[0084] Step d5, repeat steps d1-d4 to obtain the spherical degree of the other eyeball.

[0085] Preferably, the application further provides a measuring method, characterized in that the step e further comprises:

[0086] Step e1, the spherical degree test card is placed in the maximum clarity direction of step b1;

[0087] Step e2, the most clear distance d is obtained when the measured person moves one side of naked eye to the direction of the spherical degree test card, and the focal length f is:

[0088] f=d (1)

[0089] Step e3, according to the spherical degree D:

[0090] D=1 / f (2)

[0091] The first spherical degree D1 is obtained;

[0092] Step e4, the spherical degree test card is placed in the direction of the astigmatism axis, and steps e1-e3 are repeated to obtain the second spherical degree D2;

[0093] Step e5, the astigmatism degree D' of the eyeball of the measured person is calculated:

[0094] D'=D2-D1 (3)

[0095] Step e6, steps e1-e5 are repeated to obtain the astigmatism degree of the other eyeball.

[0096] Preferably, the application further provides a measuring method, characterized in that the step a comprises:

[0097] The astigmatism test card is rotated, and when the measured person observes that the clarity of the target and the black background does not change, it is determined that there is no astigmatism, otherwise there is astigmatism.

[0098] Compared with the prior art, the application does not need to use the concave spherical lens for correcting myopia, and when the measured person clearly sees the target, the focusing line is moved backward to just overlap the retina, which represents that the distance between the eye and the target is equal to the focal length. Thus, the refractive error degree and the astigmatism degree are obtained, the method of optometry is greatly simplified, and the type and quantity of the refractive error are determined very conveniently.

[0099] According to the measuring method, the use of the concave lens at a close distance is avoided, and unnecessary errors caused by the accommodation rise in the traditional optometry close distance operation are avoided. BRIEF DESCRIPTION OF DRAWINGS

[0100] The accompanying drawings are included to provide a further understanding of this application; they are incorporated into and constitute a part of this application. The drawings illustrate embodiments of this application and, together with this specification, serve to explain the principles of the invention. In the drawings:

[0101] Figure 1 This is a schematic diagram showing the linear visual target seen by a subject without astigmatism when using a traditional clock-type astigmatism meter;

[0102] Figure 2 This is a schematic diagram showing that when using a traditional clock-type astigmatism meter, astigmatic subjects may see linear targets.

[0103] Figure 3 This is a schematic diagram of the composition of the refractive test card 30 according to the first preferred embodiment of the present invention;

[0104] Figure 4 This is a schematic diagram of the composition of the refractive test card 40 according to the second preferred embodiment of the present invention;

[0105] Figure 5 This is a schematic diagram of the composition of the refractive test card 50 according to the third preferred embodiment of the present invention;

[0106] Figure 6(1) and 6(2) It is a comparison diagram of the crosshair target at different angles and positions during the test;

[0107] Figure 7(1) and 7(2) This is a comparison diagram showing the appearance of the crosshair at different angles and positions during the test;

[0108] Figure 8(1) and 8(2) This is a comparison diagram showing the appearance of the crosshair at different angles and positions during the test;

[0109] Figure 9 This is a schematic diagram of light focusing in a subject with simple astigmatism;

[0110] Figures 10(A) to 10(C) This is the view on the retina during an astigmatism test.

[0111] Figure 11 This is a flowchart of the complete testing method using the test card of this invention;

[0112] Figure 12 A schematic diagram of light focusing when viewing a target during the testing process of spherical power refractive error is given;

[0113] Figure 13 yes Figure 11 Detailed flowchart of step 1;

[0114] Figure 14 yes Figure 11Detailed flow chart of Step 3 in the method;

[0115] Figure 15 is Figure 11 Detailed flow chart of Step 4 in the method.

[0116] Reference numerals

[0117] 04 - eyeball

[0118] 30 - astigmatism test card

[0119] 31 - black background

[0120] 32 - white long bar visual target

[0121] 33 - partition unit

[0122] 40 - astigmatism test card

[0123] 41 - black background

[0124] 42 - white cross visual target

[0125] 43 - partition unit

[0126] 50 - spherical degree test card

[0127] 51 - black background

[0128] 52 - red long bar visual target

[0129] 53 - partition unit DETAILED DESCRIPTION

[0130] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the following will briefly introduce the drawings needed to be used in the embodiment description. Obviously, the drawings in the following description are only some examples or embodiments of the present application, and for those skilled in the art, the present application can be applied to other similar scenarios without creative labor on the basis of these drawings. Unless it is clear from the language context or otherwise indicated, the same reference numbers in the drawings represent the same structure or operation.

[0131] As shown in the present application and claims, unless the context clearly indicates otherwise, the words "one", "an", "a", and / or "the" do not specify a singular form, but also include a plural form. Generally, the terms "comprise" and "include" only indicate that the steps and elements explicitly identified are included, and these steps and elements do not constitute an exclusive list, and the method or device can also include other steps or elements.

[0132] The foregoing is a summary and thus contains only the most basic embodiment. The application can be practiced with the specific embodiments and options described herein, and it can also be practiced without such specific embodiments and options. Furthermore, the preceding description and drawings should not be construed as limiting the application. Numerous and various embodiments can be derived from this description without departing from the application. The description and drawings are illustrative only, and the scope of the application is defined only by the appended claims. The embodiments described herein are intended to be merely illustrative of the principles of the application. Numerous modifications may

[0133] In the description of the present application, it should be understood that the orientation words such as "front, back, upper, lower, left, right", "transverse, vertical, perpendicular, horizontal" and "top, bottom" and the like indicated orientation or position relationship are generally based on the orientation or position relationship shown in the drawings, only for the convenience of describing the present application and simplifying the description, without the opposite description, these orientation words do not indicate and imply that the indicated device or element must have a particular orientation or be constructed and operated in a particular orientation, therefore, it cannot be understood as a limitation on the scope of protection of the present application; the orientation words "inner, outer" refer to the inner and outer relative to the contour of each component.

[0134] For the convenience of description, spatial relative terms such as "over", "above", "upper surface", "upper" and the like can be used herein to describe the spatial position relationship of one device or feature with other devices or features as shown in the drawings. It should be understood that the spatial relative terms are intended to include different orientations in use or operation in addition to the orientation of the device described in the drawings. For example, if the device in the drawing is inverted, the device described as "above" or "over" other devices or structures will be positioned "below" or "under" other devices or structures. Thus, the example term "above" can include both "above" and "below" orientations. The device can also be positioned in other different ways (rotated 90 degrees or in other orientations), and the spatial relative descriptions used herein are interpreted accordingly.

[0135] In addition, it should be noted that the use of "first", "second", and / or the like herein is merely to distinguish one element from another, and is not intended to limit the scope of the application unless otherwise indicated. Moreover, the use of terminology in the specification is chosen over the use of other terminology solely for the purpose of clarity, and is not intended to limit the scope of the application. In addition, although the terms used in the present specification are selected from generally used terms, some of the terms mentioned in the specification can be selected by the applicant at his or her discretion, and their detailed meanings are disclosed in pertinent parts of the description herein. Furthermore, the present application should not be understood to be limited only to the actual terms used but also to encompass the meanings of each term.

[0136] Flowcharts have been used in the present application to illustrate the operations performed by the system according to the embodiments of the present application. It should be understood that the foregoing or the following operations are not necessarily performed in the order. Rather, the steps can be processed in reverse order or simultaneously. Also, other operations can be added to or removed from these processes, or one or more steps can be removed from these processes.

[0137] Embodiment 1

[0138] Figure 3 A schematic diagram of a refraction test card according to a first preferred embodiment of the present application is given.

[0139] The test card 30 is a refraction test card composed of a black background 31 and a single white long bar optotype 32, and is not limited to the above combination of white and long bar, but requires:

[0140] First, the test card 30 is a black background 31;

[0141] Second, the test card 30 has a horizontal white long bar optotype 32 in the center, which is 260 mm long and 5 mm wide.

[0142] The white long bar optotype 32 has a partition unit 33 in the center, which is 1.5 mm wide and 5 mm high. The partition unit 33 is not limited to a rectangular shape, a circular shape, or other shapes.

[0143] Among them, under the black background 31, the black and white contrast is very strong and obvious at the edge. This is conducive to the subject to easily distinguish between blur and clarity at a relatively long distance. This is very suitable for judging the direction of astigmatism axis.

[0144] Therefore, the astigmatism bar test card 30 having the above structure is a preferred embodiment.

[0145] Embodiment 2

[0146] Figure 4 A schematic diagram of an astigmatism test card according to a second preferred embodiment of the present application is given.

[0147] The test card 40 is a black background 41 and a single white cross-shaped visual target 42, which is not limited to the above combination of white and long strip, and the following variations are required:

[0148] First, the background of the test card is black;

[0149] Second, the central part of the test card has two long strips that are 90° to each other;

[0150] Third, each long strip is 260 mm long and 5 mm wide;

[0151] Fourth, in order to avoid the intensive effect, a partition unit 43 is specially provided in the center of the cross-shaped visual target, which is a square space with a side length of 6 mm.

[0152] The reason for selecting the white astigmatic strip visual target in the foregoing two embodiments is:

[0153] In a black background, the black and white contrast is very strong and obvious at the edge. This is conducive to the subject to easily distinguish between blur and clarity at a relatively long distance. This is very suitable for judging the direction of astigmatic axis.

[0154] Embodiment 3

[0155] Figure 5 A schematic diagram of the visual target card of the third preferred embodiment of the present application is given.

[0156] The test card 50 is a black background 51 and a single red long strip-shaped visual target 52, which is not limited to the combination of red and long strip, but requires:

[0157] First, the background of the test card 50 is black;

[0158] Second, the central part of the test card 50 has a horizontal long strip red visual target 52, which is 260 mm long and 5 mm wide;

[0159] Third, the center of the red long strip visual target 52 has a black rectangular partition unit 53, which is 1.5 mm wide and 5 mm high. The partition unit 53 is not limited to a rectangular shape, a circular shape, or other shapes.

[0160] Among them, the reason for selecting the red spherical degree visual target is:

[0161] In the clinical refraction method, the measurement deviation of spherical power caused by red and green light is about 0.5DS. Red target can offset the involuntary increase of spherical power caused by near source accommodation and convergence because the formed image is relatively posterior and close to the retina. Green target cannot offset the involuntary increase of spherical power caused by near source accommodation and convergence because the formed image is relatively anterior and far from the retina. For this reason, red spherical power target is applied to the inventive refraction method.

[0162] The basic flow of applying the test card in the above embodiment to measure refractive error is as follows:

[0163] The refractive test card 30 or 40 is applied to determine whether there is clinically required refractive error, and if there is refractive error, it is necessary to determine whether there is clinically significant astigmatism.

[0164] Figure 11 The main flow steps of the measurement method of the application are given as follows:

[0165] Step 1, using the refractive test card 30 or 40 to determine whether the measured person has astigmatism;

[0166] Step 2, if it is determined that there is clinically significant astigmatism, find the astigmatism axis;

[0167] Step 3, using the refractive test card 50 to measure and obtain near / distance spherical power;

[0168] Step 4, for the person with astigmatism, the difference between the strongest and weakest spherical power is used to calculate and obtain astigmatism.

[0169] The final results of the above measurement of the measured person include the following four cases:

[0170] Case 1: neither astigmatism nor near / far vision;

[0171] Case 2: astigmatism without near / far vision, the related parameters of astigmatism are obtained through steps 2 and 3;

[0172] Case 3: no astigmatism but near / far vision, the related parameters of near / far vision are obtained through step 3;

[0173] Case 4: if there is both astigmatism and near / far vision, the related parameters including astigmatism and near / far vision are obtained through steps 2, 3 and 4.

[0174] The following will introduce the test method of the refractive test card of the application and the detailed process of the above steps in combination with Figure 11 , Figure 13 , 14 and 15.

[0175] Step 1, judging whether the measured person has clinical astigmatism, specifically:

[0176] Step 11, at a distance of about 5 meters from the measured person, the testee watches the astigmatism test card 30 of a single white long bar visual target 32 under a black background 31;

[0177] The test card 30 uses artificial lighting, such as direct direct lighting method, the illuminance should not be less than 300lx, and the lighting should be uniform, constant, non-reflective and non-dazzling.

[0178] Step 12, the measured person measures with naked eyes, single eye measurement, generally first measures the right eye, and then measures the left eye.

[0179] When measuring one eye, the other eye needs to be covered. The measured person must keep his head straight and cannot be tilted. During testing, the measured person can naturally blink to ensure that the eyeball is moist and not dry, avoiding affecting the clarity of vision due to dryness.

[0180] Step 13, slowly rotate the test card 30 counterclockwise;

[0181] Step 14, determine whether there is astigmatism and determine the astigmatism axis according to the viewing situation of the measured person.

[0182] When the measured person has no clinically significant astigmatism, it means that there is only a single spherical power, so there is only one focusing line. At this time, when the test card 30 is rotated in any direction, the measured person sees that the contrast clarity and fuzziness of the white long bar visual target 32 and the black background 31 are similar, and there is no special clear situation in a certain direction, which indicates that the measured person has no clinically significant astigmatism.

[0183] If the opposite situation occurs, that is, during the rotation of the test card 30, the contrast clarity of the measured person changes, which can be determined as clinically significant astigmatism. If the measured person indicates that he cannot see clearly, he can be asked to move forward a few steps to approach the white long visual target, and stop when he sees the obvious white long visual target. Start testing.

[0184] Some people may not be sensitive to rotation and may not easily distinguish the visual changes of the white long bar visual target 32 during rotation. For such measured persons, the test card 40 of the white cross visual target 42 in Example 2 can be used instead.

[0185] The method steps are the same as above. In step 14, the basis for judgment changes to whether the clarity of the two long bars from the horizontal and vertical lines is similar or one is relatively blurred compared to the other.

[0186] If the long bars in the 0°-180° direction are blurred and the long bars in the 90°-270° direction are clear, the cross-shaped target 42 is rotated in the 90°-270° direction by ±10° to find the accurate position of the astigmatism axis.

[0187] When the two horizontal and vertical lines are not obviously different, the astigmatism axis is not on the two lines. The cross-shaped target 42 is placed on the four bars corresponding to 45°, 135°, 225° and 315°. The tester is asked again whether the two long bars are clear or one is blurred.

[0188] If the tester still thinks that there is no difference, the cross-shaped target 42 is placed on the four bars corresponding to 22.5°, 112.5°, 202.5° and 292.5°. The tester is asked again. In this way, the cross-shaped target 42 can correspond to 11.25°, 101.25°, 191.25° and 281.25°, etc.

[0189] The rule is that the two long bars of the white cross-shaped target 42 are always perpendicular to each other, but the angle changes in each display, and the angle is adjusted from horizontal and vertical to:

[0190] Half of 90°-45°

[0191] Quarter of 90°-22.5°

[0192] Eighth of 90°-11.25°

[0193] Sixteenth of 90°-5.625°

[0194] Thirty-second of 90°-2.8125°

[0195] The tester finds a cross-shaped target with one blurred bar and the other clear bar. After finding this position, the exact astigmatism axis is found by rotating the single long bar in the range of ±10°.

[0196] Figure 6(1) and 6(2) ~ Figure 8(1) and 8(2) The above-mentioned different angle positions of the cross-shaped target 42 in the test process are shown in the following contrastive diagrams.

[0197] That is, the cross-shaped target shown in FIG. 6(1) corresponds to 0°, 90°, 180° and 270°, respectively;

[0198] The cross-shaped target shown in FIG. 6(2) corresponds to 45°, 135°, 225° and 315°, respectively.

[0199] The cross-shaped visual target shown in Fig. 7(1) corresponds to 22.5°, 112.5°, 202.5° and 292.5° respectively;

[0200] The cross-shaped visual target shown in Fig. 7(2) corresponds to 11.25°, 101.25°, 191.25° and 281.25° respectively;

[0201] The cross-shaped visual target shown in Fig. 8(1) corresponds to 5.625°, 95.625°, 185.625° and 275.625° respectively;

[0202] The cross-shaped visual target shown in Fig. 8(2) corresponds to 2.8125°, 92.8125°, 182.8125° and 272.8125° respectively.

[0203] If the subject has no change in contrast acuity at any position of the astigmatism test card 30, it is determined that there is no clinically significant astigmatism; if it is the astigmatism test card 40, the subject has no difference in any position at any angle at any position, that is, in any case, the two cross-shaped acuities or blurs are the same and there is no difference, and it is determined that there is no astigmatism.

[0204] Returning to step 1, when step 1 determines that there is no clinically significant astigmatism, it is determined that there is only spherical refractive error, at which time step 2 is skipped and the near and far vision refractive measurement is directly continued, that is, the subject continues to look at the single red long visual target 52 on the black background 51 visual target spherical degree test card 50;

[0205] It should be noted that for a subject with myopia and no clinically significant astigmatism, he has only one focal line and it is in front of the retina, so the image will be blurred. Traditionally, a general optometry method is used to find a suitable myopia-correcting concave spherical lens to move the focal line back to the retina to obtain a clear image, that is, the focal line and the retina overlap, at which time a good vision effect is achieved.

[0206] The originality of the present application lies in:

[0207] No concave spherical lens for correcting myopia is needed, only the subject moves forward to approach the visual target until the clear visual target is just seen. At this time, the focal line is moved back to just overlap the retina, which represents that the distance between the eye and the visual target is equal to the focal length. Therefore, this distance can be used to calculate the refractive error degree of the subject.

[0208] Further, the specific method steps for measuring spherical degree refractive error are as follows: Figure 14 The details are as follows:

[0209] Step 21, at a distance of about 5 meters from the subject, show him the spherical power test card 50 of a single red long bar visual target 52 under a black background 51.

[0210] The test card 50 should be artificially illuminated, such as by direct illumination, with an illuminance of no less than 300 lx, and the illumination should be uniform, constant, non-reflective, and non-dazzling. The test card should avoid direct sunlight or strong light.

[0211] Step 22, the subject measures with naked eye, single eye, generally first measures the right eye, and then measures the left eye.

[0212] When measuring one eye, the other eye needs to be covered. The subject must keep his head straight and cannot be tilted. The subject can naturally blink to ensure that the eyeball is moist and not dry, to avoid affecting the clarity of vision due to dryness.

[0213] Step 23, first perform a simulation test, the purpose is to avoid the subject not reaching the focusing distance or exceeding the focusing distance with additional adjustment, affecting the test results; during the simulation test, the single eye needs to be covered, and the subject starts from a distance of about 5 meters and slowly moves forward to approach the single red long bar visual target 52 under the black background, first feels the visual target blurred, then the visual target is relatively clear, and then the visual target is completely clear. At this time, the subject continues to move forward and then slowly retreats to observe the change in the clarity of the visual target.

[0214] Step 24, the formal test begins, and the subject, with the single eye covered, starts from a distance of about 5 meters and slowly moves forward to approach the single red long bar visual target 52 under the black background 52, and stops moving as soon as the horizontal visual target is clear. Note that during the forward movement, you cannot move forward after retreating. If the subject's pace is relatively large and fast and cannot distinguish the position where the visual target changes from blurred to clear, you need to return to the starting point, slow down the pace, and start again.

[0215] Figure 12 The position of this test process is given, that is, the light focusing diagram when the eyeball without astigmatism looks at the visual target.

[0216] Where 04 represents the eyeball, C is the cornea, M is the retina, O is the visual target, and f represents the focal length, that is, the distance d between the subject's eye and the visual target when the subject first sees the visual target clearly.

[0217] When the subject looks at the visual target O at a distance of ≥ 6 meters, the light from each point of the visual target O is parallel when it reaches the cornea C, and the spherical power in the horizontal direction is 0 DS, so the converging power is the weakest. Therefore, the horizontal light will be focused on the back focal line, and at this time the back focal line is just superimposed on the retina M. When the subject sees the visual target O clearly, record the value of the distance d, which is the distance from the eyeball 04 to the visual target O. At this time:

[0218] d = f (1)

[0219] Where f is focal length, unit: meter (m).

[0220] To improve accuracy, the measured person needs to repeat 5 times in the same inspection, because his subjective adjustment state may change during the inspection process, so several times are needed to take the average to improve accuracy and reduce the difference caused by his adjustment state fluctuations. The average value of f is obtained from 5 values.

[0221] After completing the horizontal direction, start measuring the vertical direction, rotate the test card 90° to make the single red long target 52 on the black background vertical, repeat steps 23 and 24.

[0222] According to the spherical degree formula:

[0223] D = 1 / f (2)

[0224] Where D (Diopter) is the spherical degree, also called diopter.

[0225] Since when the measured person sees the target O clearly, f is exactly equal to d, so according to the value of d, the spherical degree of the measured person can be calculated.

[0226] Step 25, according to the horizontal and vertical directions, or the astigmatism axis and its ±90° direction, the average value is the spherical degree.

[0227] Take the average value of D obtained in the horizontal and vertical directions of the single red long target 52 on the black background as the spherical degree D of this eye, or the average value of D obtained in the astigmatism axis and its ±90° direction as the spherical degree of this eye. (The difference between horizontal and vertical is not greater than 0.25, if greater than 0.25, there is astigmatism, the astigmatism axis must be measured again, and d and D are measured in the astigmatism axis and the astigmatism axis ±90° direction.)

[0228] Step 26, after one eye ball is completed, repeat the above steps 23-25 to measure the spherical degree of the other eye ball of the measured person.

[0229] For steps 21-26, combined with Figure 12 , the calculation process of spherical degree is illustrated as follows:

[0230] The following table records the measured value of distance d each time, and the calculation result of spherical degree.

[0231] When myopia, the degree before the need to add "-".

[0232] Please refer to the following table 1:

[0233]

[0234] The average sphere of the eye is -2.209

[0235] The average sphere of the left eye is -2.318

[0236] The average sphere of the eye D = [(-2.209) + (-2.318)] ÷ 2 = -2.264

[0237] And for the measurement of the sphere of hypermetropic refractive error:

[0238] For a subject with hyperopia and no clinically significant astigmatism, if the visual acuity is greater than 1.0 at 6 meters, then there is hypermetropic refractive error. For hypermetropic refractive error, some (or several) convex lenses (positive sphere) are provided to adjust the hypermetropia.

[0239] In the case of a summary of the hypermetropic degree, the hypermetropic degree, the difference between the hypermetropic degrees in two axes, the measurement method of the astigmatism of the hypermetropic subject, and the nearsightedness are the same.

[0240] There are three degrees of lenses for different subjects to choose from when hypermetropic, one lens is +2DS, one lens is +4DS, and one lens is +6DS. Theoretically, the combination is at most 6+4+2 = +12DS, (the minimum +2DS), and the superimposed combination of different lenses can be +2, +4, +6, +8, +10, and +12DS, which can cover almost all degrees.

[0241] For example: there is a person who has 100 degrees of hypermetropia. From a visual point of view, the light emitted by objects at 6 meters and beyond is parallel when it reaches the eye, (assuming the eye has no refractive problems), and the parallel light entering the eye will focus on the retina, so hypermetropia cannot be measured by the above conventional method of nearsightedness degree. The conventional method is to go to an optical store, hospital or clinic by an optometrist or ophthalmologist with a convex lens to correct it back. The process of correcting it back is to reach the neutral point, which is his hypermetropic degree. And it involves undercorrection and overcorrection. When overcorrected, it is adjusted down again. Overcorrection is when the lens you adjust up exceeds his original hypermetropia, which turns him into a nearsighted state, at which point he will have blurred vision.

[0242] For a subject with hypermetropia and no clinically significant astigmatism, he can see clear targets at 6 meters, and his visual acuity is generally 1.0 or above. Giving him a convex +DS lens that exceeds the correction required will cause a clinically myopic effect. At this time, his visual acuity will decrease, and his visual acuity at 6 meters will be less than 1.0, and the target will appear blurred.

[0243] Assuming this person with +1DS, he and the tester do not know there is +1DS, first give him +2DS lens to try, theoretically overcorrected him, artificially make him 100 degrees myopic state, that is, -1DS myopia effect, as long as he reaches the myopia effect, can refer to the above process to measure myopia refractive spherical degree to find the distance that the measured person can see the visual target, calculate the degree by measuring the distance, and then put the lens with this degree, and then add the two, so you can know the original hyperopia degree. Avoid the need for a large number of lenses to the scene to give him, need professional to give him glasses and correction. By analogy, if he is +3DS, give him +2DS lens, he can see clearly at 6 meters, which means that +2DS lens is not enough, give him +4DS, which produces -1DS effect again, need to walk forward to see clearly, and can calculate the degree by measuring the distance to get the true degree; If he is +5DS, give him +6DS, you can also achieve the effect, more than +6DS, three lenses are used to achieve +8, +10, +12DS, etc. Enough to meet the range of most hyperopia. People with hyperopia above +6DS in clinical practice are very few.

[0244] Step 3, if it is judged as clinically significant astigmatism in step 1 of Figure 11 The next step is to measure the astigmatism axis and calculate the astigmatism degree, combined with Figure 9 The specific description is as follows:

[0245] When the measured person looks at visual target 32 at ≥6 meters, the light from each point of visual target 32 is parallel when reaching the cornea. Assuming that the measured person has no myopia or hyperopia but only simple astigmatism (0 / -2DCx180), the corneal curvature and converging power in the horizontal direction are the weakest, and the spherical degree is 0DS. While the corneal curvature and converging power in the vertical direction are the strongest, and the spherical degree is -2DS. Therefore, the light in the horizontal direction will be focused on the back focal line, which is just superimposed on the retina at this time. Similarly, the light in the vertical direction will be focused on the front focal line, which is in front of the retina at this time.

[0246] Figure 10(A) , 10(B) and 10(C) show the changes of the front and back focal lines of this measured person (0 / -2DCx180) when looking at the visual target images in the horizontal direction or the vertical direction.

[0247] For the person with myopic astigmatism, he also has two different spherical powers, one is the weakest, and the other is the strongest. The weakest spherical power and the strongest spherical power will form their own focusing line respectively, and the distance of the two focusing lines from the retina is different. At this time, the focusing line farthest from the corneal center is called the posterior focusing line, and the focusing line closest to the corneal center is called the anterior focusing line. The anterior and posterior focusing lines are also deviated from each other by ±90° on the axis.

[0248] The astigmatism axis is measured, and the specific method steps are as follows:

[0249] Step 11: The person being measured looks at the refractive test card 30 of a single white long strip 32 on a black background at a distance of 5 meters.

[0250] The test card should be artificially illuminated, such as using direct illumination method, and the illumination should not be less than 300lx. The illumination should be uniform, constant, non-reflective, and non-dazzling. The test card should avoid direct sunlight or strong light.

[0251] Step 12: The person being measured measures with one eye naked, generally first measuring the right eye and then measuring the left eye. When measuring one eye, the other eye needs to be covered.

[0252] The person being measured must keep his head straight and cannot be tilted.

[0253] Step 13: Slowly rotate the white test long strip counterclockwise.

[0254] Slowly rotate the astigmatism test card counterclockwise, and let the person being measured see which direction the white long strip looks clearer. The rotation speed should not be higher than 12.5° / s.

[0255] Step 14: Determine whether there is astigmatism and determine the direction of the astigmatism axis according to the viewing situation of the person being measured.

[0256] For the person with myopic astigmatism, when looking at the single white long strip-shaped astigmatism test card on a black background, the image will focus on two focusing lines, both in front of the retina, one relatively close to the retina, and the other relatively far from the retina. The image produced by the focusing line relatively close to the retina is clearer than the image produced by the focusing line relatively far from the retina.

[0257] First, record the direction angle that he sees the relatively clearest degree (produced by the posterior focusing line). Then, repeatedly rotate the single white long strip-shaped astigmatism strip clockwise and counterclockwise, and let the person being measured find the clearest direction. The found clearest direction (angle) plus or minus 90° is the astigmatism axis.

[0258] In addition, the astigmatism degree needs to be measured and calculated, and the specific steps are as follows:

[0259] Step 31, the subject looks at the test card 50;

[0260] Step 32, the direction of the red long bar optotype 52 of the test card 50 is adjusted to be consistent with the direction in which the subject observes the maximum clarity of the white long bar optotype with the obtained astigmatism axis;

[0261] Steps 33, 34 and 35, the phenomenon that the subject moves forward to approach the optotype 52 to cause the rear shift of the focusing line is utilized. The subject starts from a distance of about 5 meters, slowly moves forward to approach the optotype 52 until the first time the optotype is clear, at which time the distance from the eye of the subject to the optotype is measured, so that the weakest spherical degree can be obtained. The distance d at which the subject moves to the optotype 52 to obtain the clearest image at this time is measured, and the focal length f is calculated:

[0262] f = d (1)

[0263] Then the spherical degree D is:

[0264] D = 1 / f (2)

[0265] Thus, the first spherical degree D1 is obtained.

[0266] Step 35, then, the subject returns to the position of 5 meters. After the direction of the optotype 52 is rotated by 90° to be consistent with the direction of the astigmatism axis, the subject is requested to slowly move forward to approach the optotype 52 until the optotype is clear again. At this time, the distance from the eye of the subject to the optotype 52 is measured again, so that the strongest spherical degree D2 can be obtained. (Note: at this time, the rear focusing line has moved to the back of the retina, and the image caused by it is blurred, so the subject will only notice the clear image caused by the current focusing line when it is superimposed on the retina.)

[0267] Step 36, the rear focusing line is caused by the weakest spherical degree, and the front focusing line is caused by the strongest spherical degree. Since the difference between the strongest and the weakest spherical degree is the astigmatism degree, the astigmatism degree can be calculated according to the difference between the two spherical degrees (the strongest minus the weakest).

[0268] That is, the astigmatism degree D' of the eye of the subject is:

[0269] D' = D2 - D1 (3)

[0270] In the examination of the spherical degree of ametropia, the weakest spherical degree (myopia is negative) when the rear focusing line is superimposed on the retina is first examined. Then, the strongest spherical degree (myopia is negative) when the front focusing line is superimposed on the retina is examined. Then, the astigmatism degree can be obtained by subtracting the weakest spherical degree from the strongest spherical degree, and the astigmatism degree is also negative. For example: (-5DS) - (-3DS) = -2DC.

[0271] The advantage of this calculation is that each astigmatism is represented by a negative number, and a larger negative number minus a smaller negative number still results in a negative number. This avoids the confusion and errors that can occur when the number is positive at times and negative at other times.

[0272] Generally, an angle deviation of no more than 5° in clinical astigmatism axis measurement is acceptable, and the method of the present application can achieve a deviation of no more than 2.5°.

[0273] Repeat the above steps to obtain the astigmatism of the other eye.

[0274] Combining Figure 15 , the measurement and calculation method of astigmatism is as follows:

[0275] 1. On the basis of the measured astigmatism axis, further measure the spherical power of astigmatism. Use a single red long strip-shaped target spherical power test card on a black background, and the angle of the red long strip-shaped target is consistent with the most clear angle direction when the measured person rotates the single white long strip-shaped astigmatism bar. Measure, record and calculate the spherical power according to the calculation method of spherical power described in steps 24 and 25 above, so as to obtain the weakest and strongest spherical power. Similarly, simulation testing is required before formal testing.

[0276] 2. Like other normal people, the measured person generally has a fluctuation in the subjective adjustment state during the test. The measurement is done 5 times, which greatly reduces the difference in the value caused by the fluctuation in the adjustment state of the measured person and the single measurement, and the average of 5 times greatly reduces the deviation and achieves the accuracy required in clinical practice. At this time, the average value of f is the weakest spherical power of the measured person in daily life.

[0277] 3. Then rotate the red long strip-shaped target by 90° to point to the direction of the astigmatism axis (that is, the direction of the most clear angle ± 90° of the white long strip-shaped target in the “astigmatism axis measurement method step 13”). For example, rotate the 15° obtained from the most clear white target to 105°, and so on. Measure, record and calculate the spherical power according to the calculation method of spherical power described in the above process 26, so as to obtain the strongest spherical power of the measured person in daily life.

[0278] 4. Obtain the astigmatism from the weakest and strongest spherical power.

[0279] Subtract the weakest spherical power obtained in step 34 from the strongest spherical power obtained in step 35, that is, subtract the spherical power after rotation by 90° from the spherical power before rotation by 90°, to obtain the astigmatism of the measured person.

[0280] An example of the calculation process of astigmatism is as follows:

[0281] The following table records the measurement of distance d each time, and the calculated spherical power.

[0282] When myopia, the degree before the plus "-".

[0283] Please see the following meaning:

[0284]

[0285] Before the target rotates 90°, the average spherical power of the eye is -3.734DS

[0286] After the target rotates 90°, the average spherical power of the eye is -4.160DS

[0287] → The astigmatism of the eye D = [(-4.160) - (-3.734)] = -0.426DC

[0288] Myopia plus astigmatism of the measured person:

[0289] When a measured person has -2DS myopia and -3DC astigmatism, the astigmatism axis is 90° (indicating that the weakest spherical power is -2DS, the strongest is -5DS, and the difference is -3DC. The axis is at 90°). This represents that his back focal line is generated by -2DS myopia, and his front focal line is generated by this additional -3DC myopia astigmatism. (In fact, because he is (-2) + (-3), it is the result of (-5DS). When his astigmatism axis is 90°, it represents that his converging power is on the 180° line. The focusing power of the additional -3DC astigmatism is on the 180° line.

[0290] In terms of the measured person, when the target and the back focal line are in the same direction, -2DS myopia represents that when the measured person is 0.5 meters away from the target, he will produce a clear target image, because the back focal line just overlaps on the retina at this time, so a clear target will be produced. The front focal line does not constitute a clear target image because it deviates 90° from the direction of the target. Then turn the target 90°, at this time, the direction of the target and the front focal line are in the same direction, and the back focal line deviates 90° from the direction of the target, so it does not constitute a clear target image. When the measured person walks to 0.2 meters (at this time D is -5DS), the front focal line just overlaps on the retina to produce a clear target image.

[0291] Hyperopia plus astigmatism of the measured person:

[0292] For such a person, a convex lens is added to the person, and the person becomes myopic, and then the spherical degree, astigmatism degree and astigmatism axis of the person can be obtained according to the above process.

[0293] In summary, the spherical degree of hyperopia, the spherical degree of myopia, the astigmatism degree and the astigmatism axis can be obtained through the above operation.

[0294] It should be particularly pointed out that the present application is not limited to the black background of the above-mentioned refraction test card, nor is it limited to red or white targets, but can also use color combinations with certain contrast, such as blue + yellow, to identify the target during testing.

[0295] The test card and the refraction method using the test card of the present application are simple and easy to operate compared with traditional methods, do not require complex equipment and instruments, and are suitable for ordinary people to measure at home. The method is easy to understand and easy to master, and has high accuracy.

[0296] More importantly, the person being tested is generally tested in the most relaxed or nearly most relaxed adjustment state without the need for external lens or conversion insert. In this case, unnecessary interference and thus unwanted adjustment or change of adjustment state are greatly reduced. This method also avoids errors in refraction degree caused by subjective and experiential bias of the refraction personnel.

[0297] In addition, the above-mentioned method of the present application can be realized by application software. The software can be installed on a computer, a mobile phone or a tablet computer, and by operating directly on these interactive terminals, the required test content can be selected, and the data can be recorded and processed. The displayed image content can be played on a computer display screen, a television or projected onto a curtain wall.

[0298] The application has two versions of online APP and offline APP.

[0299] The online APP version mainly stores the core data in the cloud server, and only a small amount of data is downloaded to the interactive device end (iPad, etc.) for the user to select and install the device, and the data is processed through communication connection with the background server.

[0300] The offline APP version downloads all data directly to the interactive terminal device, and then binds the device for use.

[0301] The simple and objective refraction method of the present application (including the spherical degree of myopia and hyperopia, the astigmatism degree and the astigmatism axis) is also simple and clear.

[0302] The simple and clear target is:

[0303] A single white long bar test chart on black background (not limited to other color and shape combinations) to measure the presence or absence of astigmatism and the axis of astigmatism. Using it for refractive error examination, the axis of astigmatism can be found accurately to ±2.5°, more accurate than the traditional ±5°.

[0304] A single red long bar test chart on black background (not limited to other color and shape combinations) to measure the spherical power. Using it for refractive error examination, the spherical power and astigmatism power can be calculated.

[0305] The foregoing merely illustrates the principles of the application. Various modifications and alterations to the described implementations will be apparent to those skilled in the art in view of the foregoing description. It will be appreciated that each of the modifications and alterations and any further modifications or alterations to the implementations described herein can be made in the spirit of the present application and further fall within the scope of the application. Therefore, the particular implementation or implementations selected for use are not to be considered in a limiting sense for the present application. Rather, the present application is to be accorded the broadest scope consistent with the principles and numerous embodiments and modifications as set forth in the following claims.

[0306] The detailed description set forth above discloses merely exemplary embodiments of the application and is not intended to limit the scope of the application. As is indicated although specific words have been used herein, they are used in an illustrative sense and should not be taken in a limiting sense, as numerous modifications and adaptations thereof will be apparent to those skilled in the art. Accordingly, the specific embodiments disclosed above are illustrative only and should not be taken as limiting the scope of the application as defined by the following claims.

[0307] Some aspects of the application can be performed, executed, implemented, or facilitated in their entirety by hardware, in their entirety by software (including firmware, resident software, micro-code, etc.), or by combinations of both. The hardware or software can be referred to as a "block," "module," "engine," "unit," "component," or "system." A processor can be one or more application specific integrated circuits (ASICs), digital signal processors (DSPs), digital audio player devices (DAPDs), programmable logic devices (PLDs), field programmable gate arrays (FPGAs), processors, controllers, micro-controllers, microprocessors, or combinations thereof. Further, aspects of the application can be embodied as a computer product, including a computer-readable medium having stored thereon computer-readable program codes. The computer-readable medium can include, but is not limited to, magnetic storage devices (e.g., hard disk; floppy disk), optical disks (e.g., compact disk (CD); digital versatile disk (DVD)), smart cards, and flash memory devices (e.g., card; stick; key drive).

[0308] A computer-readable medium may contain a propagated data signal containing computer program code, for example, on baseband or as part of a carrier wave. This propagated signal may take various forms, including electromagnetic, optical, and so on, or suitable combinations thereof. A computer-readable medium can be any computer-readable medium other than a computer-readable storage medium, which can be connected to an instruction execution system, apparatus, or device to enable communication, propagation, or transmission of a program for use. The program code located on the computer-readable medium can be propagated through any suitable medium, including radio, cable, fiber optic cable, radio frequency signals, or similar media, or any combination of the above media.

[0309] The basic concepts have been described above. Obviously, for those skilled in the art, the above disclosure is merely illustrative and does not constitute a limitation of this application. Although not explicitly stated herein, those skilled in the art may make various modifications, improvements, and corrections to this application. Such modifications, improvements, and corrections are suggested in this application, and therefore remain within the spirit and scope of the exemplary embodiments of this application.

[0310] Furthermore, this application uses specific terms to describe embodiments of the application. For example, "an embodiment," "one embodiment," and / or "some embodiments" refer to a particular feature, structure, or characteristic related to at least one embodiment of the application. Therefore, it should be emphasized and noted that "an embodiment," "one embodiment," or "an alternative embodiment" mentioned twice or more in different locations in this specification do not necessarily refer to the same embodiment. In addition, certain features, structures, or characteristics in one or more embodiments of the application can be appropriately combined.

[0311] Similarly, it should be noted that, in order to simplify the description of the present application and thus aid in the understanding of one or more embodiments of the invention, the foregoing description of the embodiments of the present application sometimes combines multiple features into a single embodiment, drawing, or description thereof. However, this disclosure method does not imply that the subject matter of the application requires more features than those mentioned in the claims. In fact, the embodiments contain fewer features than all the features of the single embodiments disclosed above.

[0312] In some embodiments, numbers describing the quantity of components and attributes are used. It should be understood that such numbers used in the description of embodiments are modified in some examples with the terms "approximately," "approximately," or "generally." Unless otherwise stated, "approximately," "approximately," or "generally" indicates that the numbers are allowed to vary by ±20%. Accordingly, in some embodiments, the numerical parameters used in the specification and claims are approximate values, which may be changed depending on the characteristics required by individual embodiments. In some embodiments, numerical parameters should take into account specified significant digits and employ a general method of digit reservation. Although the numerical ranges and parameters used to confirm their breadth of scope in some embodiments of this application are approximate values, in specific embodiments, such values ​​are set as precisely as feasible.

[0313] Although this application has been described with reference to specific embodiments, those skilled in the art should recognize that the above embodiments are only used to illustrate this application, and various equivalent changes or substitutions can be made without departing from the spirit of this application. Therefore, any changes or modifications to the above embodiments within the essential spirit of this application will fall within the scope of the claims of this application.

Claims

1. A refractive test card, characterized in that, A visual target is included against a black background, and a partition unit is included at the center of the visual target, which visually separates the visual target. The test card includes an astigmatism test card and a spherical power test card, wherein the astigmatism test card includes a white strip-shaped visual target and a cross-shaped visual target, and the spherical power test card includes a red strip-shaped visual target; The length of the target is 260mm ± 50mm, and the width is 5mm ± 2mm; The width of the partition unit is less than or equal to 5mm, and the height range is 5mm ± 2mm; During use, the astigmatism test card needs to be rotated slowly.

2. The refractive test card according to claim 1, characterized in that, The target includes a strip-shaped target, and the color of the strip-shaped target includes either white or red.

3. The refractive test card according to claim 2, characterized in that, The target includes a cross-shaped target, and the color of the cross-shaped target includes white.

4. The refractive test card according to claim 3, characterized in that, The shape of the partition unit can be either rectangular or circular.

5. A measurement method using any one of the refractive test cards according to claims 1 to 4, characterized in that, include: Step a: Determine whether the subject has astigmatism based on the clarity of the contrast between the visual target and the black background observed by the subject on the astigmatism test card; Step b: If it is determined that the subject has astigmatism, the direction of the astigmatism axis is determined; if there is no astigmatism, proceed to step d and end. Step c: Determine whether the subject has myopia or hyperopia based on the clarity of the contrast between the optotype and the black background observed by the subject on the spherical power test card. Step d: Test and calculate the sphericity of the subject. Step e: If astigmatism is present, continue testing and calculate the astigmatism degree of the subject.

6. The measurement method according to claim 5, characterized in that, The measurement of the astigmatic axis direction in step b includes: Step b1: The subject measures the astigmatism test card with uncorrected vision on one side by rotating the card at a rate not exceeding 12.5° / second to obtain the direction of maximum sharpness observed by the subject. Step b2: Determine the maximum sharpness direction ±90° as the astigmatic axis direction.

7. The measurement method according to claim 6, characterized in that, Step d further includes: Step d1: Obtain the distance d at which the subject's naked eye moves towards the spherical power test card and measures the point of sharpest focus, and the focal length f: f = d (1) Step d2, based on the spherical measure D: D = 1 / f (2) Obtain the first spherical degree D1; Step d3: Rotate the spherical degree test card by 90° and repeat steps d1 to d2 to obtain the second spherical degree D2; Step d4, the spherical power D of the subject's eyeball: D=(D1+D2) / 2 (3) Step d5: Repeat steps d1 to d4 to obtain the spherical power of the other eyeball.

8. The measurement method according to claim 7, characterized in that, Step e further includes: Step e1, the spherical degree test card is placed in the maximum sharpness direction of step b1; Step e2, obtain the clearest distance d and focal length f when the subject moves their naked eye toward the spherical power test card for measurement: f = d (1) Step e3, based on the spherical measure D: D = 1 / f (2) Obtain the first spherical degree D1; Step e4: Place the spherical power test card in the direction of the astigmatic axis, and repeat steps e1 to e3 to obtain the second spherical power D2; Step e5, calculate the astigmatism D' of the subject's eye: D'=D2-D1 (3) Step e6: Repeat steps e1 to e5 to obtain the astigmatism value of the other eye.

9. The measurement method according to any one of claims 5 or 6, characterized in that, In step a: Rotate the astigmatism test card. If the subject observes no change in the clarity of the target and the black background, it is determined that there is no astigmatism; otherwise, it is determined that there is astigmatism.

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