A device for visualizing calibration of astigmatic eye focal lines

Abstract

The utility model discloses a kind of visual calibration device of astigmatism eye focal line, comprising: axial position scale board, board face is printed with E-type visual target for distant visual detection;Cross visual target disc, coaxially rotatably embedded in through-hole;Several groups of pinholes, each group is arranged along visual target line two sides straight line, pinhole center connecting line is parallel with corresponding visual target line;Fixed shaft is through cross visual target disc center, and is mechanically connected with transmission device;LED light source, set in axial position scale board back surface.The utility model has beneficial effect: the utility model can provide clear and visible and invariable measured astigmatism eye objective existence astigmatism focal line of the person being examined, and can accurately determine the clear criterion that cross visual target line coincides with the focal line, so as to maximumly improve the accuracy of astigmatism eye astigmatism axial calibration, reduce the deviation of calibration astigmatism axial direction and actual astigmatism axial direction, improve determination accuracy and determination work efficiency.

Description

Technical Field

[0001] This utility model relates to the field of optical technology, specifically a visual calibration device for the focal line of an astigmatic eye. Background Technology

[0002] Astigmatic axis calibration is fundamental to astigmatic refractive examination. It directly determines the accuracy of astigmatic correction (including astigmatic axis, astigmatic power, and spherical power), the direction of correction for astigmatic lenses, and the optical corrective effect and visual quality of astigmatic glasses, preventing the accumulation of residual astigmatism. Therefore, astigmatic axis is one of the core parameters in ophthalmic diagnosis and treatment.

[0003] Currently, in the field of subjective refraction, astigmatism axis determination generally employs the astigmatism table method, slit-lens method, and cross-cylinder method. While the astigmatism table and slit-lens methods are simple to operate, their axis determination results have relatively large errors, requiring fine-tuning using other methods. The cross-cylinder method is mainly used for fine-tuning of astigmatism axis and power, but it requires initial data on the astigmatism axis, power, and spherical power. Fine-tuning of the axis and power is then performed based on this initial data, making the operation cumbersome and time-consuming. Furthermore, the results rely to some extent on the subjective judgment of the patient and the refractionist, necessitating further fine-tuning through lens refraction.

[0004] The utility model application with application number CN202420357882.6, entitled "A Cross-Mark Astigmatism Test Disc," discloses an astigmatism testing device that can conveniently determine the astigmatism axis. Its core feature is transforming the astigmatism meter into a rotatable cross-mark disc, thereby improving the accuracy of astigmatism axis determination. However, the measurement results still rely to some extent on the subjective judgment of the person being tested.

[0005] Therefore, currently used tube-based astigmatism axis measurement techniques all rely to varying degrees on the subjective judgment of the patient and the optometrist, thus affecting the accuracy of astigmatism axis measurement and failing to meet clinical needs. The root cause of these problems is that existing tube-based astigmatism measurement techniques cannot achieve precise visualization of the astigmatic line in astigmatic eyes, nor can they accurately determine and calibrate the precise location of the astigmatic line. Utility Model Content

[0006] The purpose of this invention is to provide a visual calibration device for the focal line of astigmatic eyes, so as to solve the problems mentioned in the background art.

[0007] To achieve the above objectives, this utility model provides the following technical solution:

[0008] In a first aspect, this utility model provides a visual calibration device for the focal line of an astigmatic eye, comprising:

[0009] The axis scale plate has a circular through hole with a diameter of 140-200mm in the center. The upper half of the through hole is engraved with 0°-180° axis scale counterclockwise. The plate surface is printed with E-type optotype for distance vision testing.

[0010] A crosshair sight plate is coaxially and rotatably embedded in the through hole. The plate surface has two crosshair lines, which are composed of two solid lines 2.6 mm wide with a spacing of 5 mm.

[0011] Several groups of small holes are arranged in a straight line along both sides of the target line, and the line connecting the centers of the small holes is parallel to the target line.

[0012] A fixed shaft passes through the center of the crosshair and is mechanically connected to the transmission device; an LED light source is located on the back of the shaft scale plate.

[0013] Preferably, the axis scale plate is made of 3mm thick light-transmitting acrylic sheet, the inner diameter of the through hole is 198mm, and the minimum division value of the axis scale is 1°.

[0014] Preferably, the diameter of the small hole is 4.5 mm, the center-to-center distance between adjacent small holes is 15 mm, and the center-to-center distance of the small hole closest to the visual target line is 15 mm from the visual target line.

[0015] Preferably, the transmission device includes an electric drive assembly, which is connected to the crosshair disk via a fixed shaft.

[0016] Preferably, a level is provided on the top of the axis scale plate.

[0017] Compared with the prior art, the beneficial effects of this utility model are: this utility model can provide the examinee with a clear, visible and unchanging objective astigmatic focal line of the astigmatic eye being tested, as well as a clear criterion for accurately determining whether the crosshair coincides with the focal line, thereby maximizing the accuracy of the astigmatic axis calibration, reducing the deviation between the calibrated astigmatic axis direction and the actual astigmatic axis direction, and improving the measurement accuracy and measurement efficiency. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of the front structure of the vision test chart according to an embodiment of the present invention;

[0019] Figure 2 This is a cross-sectional structural diagram of the vision test chart in this embodiment;

[0020] Figure 3 This is a schematic diagram of the crosshairs and dotted circles on the vision chart as seen by an emmetropic eye and by myopic and hyperopic eyes after vision correction in this embodiment;

[0021] Figure 4A schematic diagram (A) of the crosshairs, two bright lines, and small cylindrical spot on the visual acuity chart as seen after one focal line of an astigmatic eye is calibrated.

[0022] Figure 5 A schematic diagram (B) of the crosshairs, two bright lines, and small cylindrical spot on a visual acuity chart as seen after one focal line of an astigmatic eye is calibrated.

[0023] Figure 6 This is a schematic diagram of one of two other forms of crosshair and pinhole distribution on a crosshair target disk;

[0024] Figure 7 This is the second of two other schematic diagrams showing the distribution of crosshairs and pinholes on a crosshair target disk. Detailed Implementation

[0025] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the protection scope of the present utility model.

[0026] Please see Figures 1 to 7 This utility model provides a technical solution: a visual calibration device for the focal line of an astigmatic eye, including an axis scale plate 4 with the letter E, a crosshair target disk 3, an axis scale plate fixing plate 5, and a base plate 12 for placing a light source and a rotating device. The crosshair target disk 3 is disc-shaped, and a fixing shaft 1 passes through the central hole of the crosshair target disk 3. A fixing shaft sleeve 6 is fitted on the fixing shaft 1, and a fixing screw 2 is screwed into the screw hole on the fixing shaft sleeve 6 to fix the crosshair target disk 3 and the fixing shaft 1 into one piece.

[0027] In this embodiment, the axis scale plate 4 containing the letter E has a through hole, and the crosshair target disk 3 is located at the through hole position. The surface of the crosshair target disk 3 is flush with the surface of the axis scale plate 4. The axis scale plate 4 is fixed to the axis scale plate fixing plate 5 by four sets of connecting and fixing screws 13 located at the four corners of the plate and spacer sleeves 14. The axis scale plate fixing plate 5 has a hole in the center for the fixing bushing 6 fixed on the fixing shaft 1 to pass through. A transparent flat washer 9 and a backstop ring 10 are fitted on the fixing shaft 1, and the fixing nut 8 is screwed on to make the crosshair target disk 3 and the fixing plate 5 connected as one, ensuring that there is no gap between the two and that the fixing shaft 1 can easily drive the crosshair target disk 3 to rotate. The support screw on the backstop ring 10 is tightened, and the base plate 12 for placing the light source and transmission device is fixed by connecting and fixing screws 13. At the tail of the fixing shaft 1, a rotating mechanism for rotating the fixing shaft 1 is fixed.

[0028] In this embodiment, the inner diameter of the through-hole on the axis scale plate 4 containing the letter E is slightly larger than the outer diameter of the cross-shaped optotype disc 3. This embodiment has an "E"-shaped optotype 15 printed on it, corresponding to distance visual acuity measurements of 0.2-1.5. Astigmatism axis graduations 16, ranging from 0° to 180°, are engraved counterclockwise along the upper half of the inner diameter of the through-hole, with a minimum interval of 1° and a large division every 10°. Axis numbers are also marked to ensure that the optometrist's axis reading accuracy at the distance of clear vision is 0.1 degrees. A level 17 is positioned on top of the axis scale plate 4 to ensure the correct zero position of the astigmatism axis graduation 16. The outer diameter of the cross-shaped optotype disc 3 is slightly smaller than the inner diameter of the through-hole on the axis scale plate 4; in this embodiment, it is 198 mm. The crosshairs of the target disk 3 are a set of mutually perpendicular crosshairs, whose intersection point coincides with the center of the target disk 4. In this embodiment, each target line consists of two solid lines broken in the middle, with a line width of 2.5 mm. The distance between the two solid line segments and the outer side of the shaft head of the fixed shaft 1 is 5 mm. Several small holes 18 with appropriate hole spacing are evenly distributed on both sides of each target line along a straight line. In this embodiment, the distance between the evenly distributed straight line with several small holes and the target line is 15 mm. The number of small holes is 36. The center distance of the small hole closest to the center of the circle from both target lines is 15 mm. The center distance between adjacent small holes on the same straight line is 15 mm. The diameter of the small holes is 4.5 mm. The base plate 12 for mounting the light source and transmission device is a square or rectangle with the same as the astigmatic axis scale 4. This embodiment uses an aluminum alloy plate with LED beads or light strips fixed on the inner side and a mechanical or electric transmission mechanism for rotating the fixed shaft 1 installed on the outer side. This embodiment uses an electric transmission mechanism controlled by a remote control. The angular velocity of rotating the crosshair target disk is no greater than 2° / second, and the minimum rotation angle is no greater than 0.1°. The E-shaped axis scale plate 4, the crosshair target disk 3, and the scale plate fixing plate 5 are all made of white translucent acrylic sheets of appropriate thickness, with a thickness of 3mm. The targets, scales, and numbers are all UV printed. The flat gasket 9 is made of transparent organic glass. The scale plate fixing plate 5 is backlit by an LED light source, which provides a uniform diffuse reflection light source for the various targets and small holes on the scale plate 4 and the crosshair target disk 3, and can eliminate the glare caused by the gap between the mating surfaces of the scale plate 4 and the crosshair target disk 3.

[0029] In this embodiment, the specific settings of the optotypes allow a subject with visual acuity of 0.6 to clearly see the optotypes and holes (excluding axis numbers and some "E" type optotypes) with clean glasses. When an astigmatic eye observes the visual acuity chart, what they see are two equally cleaned crosshair optotype lines 31 and 36 small cylindrical light spots formed by 36 small holes with parallel axes. Rotating the crosshair optotype disk 3 connects the center lines of the holes 32 on both sides of a certain crosshair optotype line 31. The axes of the small cylindrical light spots formed by the small holes 32 coincide, and these small cylindrical light spots formed by the small holes 32 on the same straight line will connect end to end, thus forming a clear bright line. At the same time, the crosshair optotype line 31 changes from two broken solid line segments in the middle to a whole black solid line 33 connected in the middle. On the other side symmetrically, a clear bright line 34 is also formed. The direction of these two parallel bright lines is the direction of one focal line of the astigmatic eye being tested. Because this target line is parallel to the two bright lines, it automatically aligns with a focal line of the astigmatic eye. The astigmatic axis it aligns with is the axis of that focal line, thus achieving the calibration of the astigmatic axis, i.e., the direction of the focal line. This embodiment uses a crosshair to calibrate the astigmatic axis based on the following explicit calibration criteria:

[0030] In this embodiment, a clear and bright line of light is used as a calibrator that the subject can clearly see astigmatically affected eyes. This longer line, formed by multiple small holes, replaces the axis of a cylindrical spot formed by a single small hole as the calibrator, which is obviously more convenient and accurate. Since the line connecting the centers of the small holes is parallel to the crosshair, when the small cylindrical spot formed by the small holes creates a bright line, this crosshair automatically marks the astigmatic focal line. Simultaneously, the crosshair changes from two broken segments to a single, solid black line connected in the middle. This arrangement of two bright lines sandwiching a black line facilitates accurate calibration.

[0031] In this embodiment, the small cylindrical light spots 35 formed by the remaining pinholes must have an axis parallel to the crosshair and perpendicular to the axis of another crosshair 31 that forms two blurred rectangular images, which can assist in axis calibration. Since the accuracy of the pinhole center position can easily reach 0.1mm, the straightness error of the straight line formed by connecting the pinhole centers, i.e., the straightness of the bright line, is less than 0.036°, and the non-parallelism between the bright line and the corresponding crosshair is also less than 0.036°. Therefore, the overlap accuracy of the crosshair calibration of the astigmatic focal line is no greater than 0.1°, thereby ensuring the accuracy of astigmatic axis calibration, which is independent of the size of the astigmatic reading.

[0032] In this embodiment, the calibration of the astigmatic focal line (axis) and the determination of the astigmatic refractive state of the astigmatic eye are performed:

[0033] During refraction, when the visual acuity of the eye being tested gradually improves to around 0.6, if the two cross lines on the cross-shaped visual target are not equally clear (blurred), and all the small round bright spots are not small bright spots but form small cylindrical light spots with burrs and parallel axes, it indicates that the subject's eye has astigmatism, and the astigmatism refraction test is initiated.

[0034] In this embodiment, the method for calibrating the astigmatic focal line (axis) and measuring the astigmatic refractive state of an astigmatic eye are described.

[0035] 1. Determine the focal line direction of the subject's astigmatic eye. The direction of the axis of the small cylindrical light spots formed by the bright spots on the crosshair, which are parallel to each other, is the direction of the focal line corresponding to the astigmatic eye being tested.

[0036] II. Preliminary Calibration of the Focal Line in Astigmatic Eyes. The examinee uses a remote control to rotate the crosshair until the tested eye sees small cylindrical spots with parallel axes on both sides of a certain crosshair forming a spiky bright line, and the crosshair changes from two broken segments in the middle to a continuous solid line in the middle. At this point, rotation is stopped (e.g., ...). Figure 3 As shown in the figure, the preliminary calibration is complete.

[0037] III. Precise Calibration of the Astigmatic Focal Line. Adjust the subjective refractometer (fine-tune the crosshair if necessary) so that the focal line is focused on the retina. Continue until the bright line becomes the clearest, smooth, and burr-free bright line, and the target line becomes the clearest, connected solid black line. Stop the operation at this point. Both this and the small cylindrical spot are now called smooth, small cylindrical spots with their axes parallel to the bright line, while the other target line is referred to as two separate, blurred rectangular images. Figure 4 As shown, record the axis scale number P1 that the target line is aligned with at this time. Figure 4 The angle between the two points (30°) and the diopter displayed on the optometry instrument are the axis of one focal line of the subject's astigmatic eye and the diopter of the vertex.

[0038] The examinee focuses the refractometer, causing the small cylindrical spots on either side of the previously blurred visual target line to become two sharpest lines. The visual target line itself changes from two separate images to a single, sharp black line connected in the middle. The process is then stopped. The previously clear visual target line now appears as two blurred rectangular images, and the bright lines on either side transform into several small cylindrical spots with their optical axes parallel to the current bright lines, as shown in the figure. Figure 5 As shown, record the axis scale number P2 that the cleaning target line is aligned with at this time (e.g., ...). Figure 5 The astigmatism is 120° (regular astigmatism, complementary axes) and the spherical dimension M2 displayed on the optometry instrument. P2 and M2 are the periphery and vertex power of the other focal line of the astigmatic eye of the test subject.

[0039] If, when adjusting the refractometer, the small cylindrical spots on either side of the other visual target cannot form a smooth, clear bright line, and the crosshair cannot form a clear, black crosshair in the middle, this indicates irregular astigmatism. In this case, instruct the patient to fine-tune the crosshair, coordinating with the refractometer adjustment, until two clearest bright lines are formed on either side of the target, and the target becomes a clear, black crosshair connected in the middle. Stop the procedure. Record the axis number at which the target is aligned and the spherical dimension displayed on the refractometer. This axis number and spherical dimension are the axis and vertex power of the other focal line in the irregular astigmatic eye.

[0040] IV. Determination of the Astigmatic Refractive State of the Astigmatic Eye Under Test. Based on the relationship between the refractive state of the astigmatic eye under test and the fixed-focus and axis values ​​of the two focal lines, the refractive state of the astigmatic eye under test, i.e., the spherical dimension, astigmatism power, and astigmatic axis, can be labeled as follows:

[0041] 1. M1 is the spherical dimension, (M2 - M1) is the astigmatism degree, and P2 is the astigmatic axis, i.e., M1 + (M2 - M1) * P2

[0042] 2. M2 is the spherical dimension, (M1 - M2) is the astigmatism degree, and P1 is the astigmatic axis, i.e., M2 + (M1 - M2) * P1

[0043] In the two sets of expressions above, one set must have a negative astigmatism value. According to current domestic eyeglass prescription practices, this set of data is used as the prescription. Since the astigmatism axis scale is printed with the letter E corresponding to distance visual acuity of 0.2-1.5, this visual acuity chart can also be used as a distance visual acuity chart.

[0044] The working principle of this invention is as follows: In astigmatism, the refractive power of the eyeball differs along different meridians. When parallel light rays enter the eye, without the eye using accommodation, they cannot form a single focal point on the retina after passing through the eye's refractive system. Among countless meridians, one meridian has the strongest refractive power, and another has the weakest. Generally, the strong and weak meridians are perpendicular to each other. When parallel light rays enter an astigmatic eye, due to the difference in refractive power between these two meridians, they diverge at their focal points along the eye's principal axis.

[0045] The Schrödinger model of astigmatism assumes that the refractive power of an astigmatic eye is greatest on one of two mutually perpendicular meridians and least on the other, ignoring the details of other meridians. This simplifies an astigmatic eye (regular astigmatism) into a combination of two physiological cylindrical lenses with mutually perpendicular axes but different refractive powers. Their axes are perpendicular to the aforementioned strong and weak meridians, respectively. Each lens forms a focal line perpendicular to the meridian at its focal point, creating a Schrödinger ray between the two focal lines.

[0046] If the refractive power of these two physiological cylindrical lenses is changed, the focal line that is in the same direction as their axis can be moved individually, so that both focal lines are focused on the retina, thereby correcting astigmatism.

[0047] Therefore, it can be seen that as long as the two mutually perpendicular focal lines of a regular astigmatic eye are found, and their refractive power and spatial axis are measured respectively, the regular astigmatic eye can be corrected.

[0048] According to the Smithsonian optical model, because the refractive power of the strong meridian is strong, when the principal ray from the strong meridian focuses, the rays from the weak meridian continue to converge. Therefore, the rays from the strong meridian first focus at the original focal point, forming a focal line perpendicular to the strong meridian, i.e., parallel to the weak meridian, called the front focal line. Before and after the front focal line, because the refractive power of the strong meridian is greater than that of the weak meridian, the beam cross-section before and after the front focal line is elliptical, with its major axis pointing towards the weak meridian. After crossing the front focal line, the rays from the strong meridian diverge, while the rays from the weak meridian continue to converge. At a certain cross-section, the divergence and convergence in both directions are equal, and the beam cross-section is circular; this is the Smithsonian circle of least confusion. Subsequently, the weak meridian continues to converge, forming a focal line perpendicular to the weak meridian, i.e., parallel to the strong meridian, at the focal point. Since the weak meridian focuses after the strong meridian, this focal line is called the back focal line. Before and after the posterior focal line, as analyzed above, the light beam is also an ellipse with its major axis aligned with the weak meridian, i.e., parallel to the posterior focal line. Therefore, regardless of whether the anterior or posterior focal line is near the retina of an astigmatic eye, since the light beams before and after the anterior and posterior focal lines are both elliptical beams with their major axes parallel to the focal lines, the light spots they form on the retina are also elliptical spots with their major axes parallel to the anterior or posterior focal lines. The direction of the major axis of this light spot is the direction of the focal line, and the magnitude of the major and minor axes is the amount of diffusion along the weak or strong meridian of the retina. Since the focal line closest to the retina has the least diffusion, it forms a relatively clear focal line image.

[0049] When an astigmatic eye observes a small circular aperture illuminated from behind by a diffuse light source at a distance of 5 meters without accommodation, or a small black dot with a white background illuminated by a light source, a pinhole corona phenomenon occurs due to the varying amounts of diffusion on the diffuse spot of the retina. The small circular aperture or black dot observed by the astigmatic eye is neither a small dot nor an ellipse. Instead, it forms a small cylindrical spot or short cylindrical line with fuzzy edges, extending along the focal line closest to the retina and with its axis parallel to the focal line. It is evident that the axial direction of this small cylindrical spot or short cylindrical line corresponds to the direction of a focal line in the astigmatic eye, and its spatial orientation is the axis of a focal line in the astigmatic eye, i.e., the astigmatic axis.

[0050] When there are two small holes or two small dots, and the line connecting their centers is parallel to the strong or weak meridian, and the distance between their centers is controlled, so that the small cylindrical light spots or short cylindrical lines formed on the retina are connected end to end, the astigmatic eye will see a continuous light spot or continuous short line. When there are enough of these small holes or small dots, the eye being tested will see a bright line formed by the small holes or a clear black line formed by the small dots. The direction of this bright or black line is parallel to the strong or weak meridian of the astigmatic eye, and therefore is the direction of a focal line corresponding to the strong or weak meridian, that is, the direction of a focal line of the astigmatic eye. Its direction in space is the axis of a focal line, thus allowing the astigmatic patient to clearly see the objectively existing and unchanging focal line of the astigmatic eye being tested.

[0051] Using a crosshair target, align one of its lines with the aforementioned bright or clear black line. The position of this line is the position of one focal line of the astigmatic eye, thus enabling the calibration of the astigmatic axis.

[0052] Since the accuracy of determining the non-parallelism of two parallel and overlapping lines in the same plane can generally be easily achieved to within a few fractions of an inch, and the focal line of the astigmatic eye being calibrated is a clearly visible and objectively existing real focal line, the direction of the focal line of the astigmatic eye calibrated by this utility model, i.e., the astigmatic axis, is highly accurate, the method is simple and fast, and it is not affected by external interference or the degree of astigmatism. Using the same method, the direction of the other focal line of the astigmatic eye, i.e., the astigmatic axis of the other focal line, can be quickly and accurately calibrated using another line of the crosshair, thereby achieving rapid and accurate calibration of the astigmatic axis of the astigmatic eye.

[0053] Although embodiments of the present invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the present invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A visual calibration device for the focal line of an astigmatic eye, characterized in that, include: The axis scale plate (4) has a circular through hole with a diameter of 140-200mm in the center. The upper half of the through hole is engraved with 0°-180° axis scale (16) counterclockwise. The plate surface is printed with E-type optotype for distance vision testing (15). A crosshair sight plate (3) is coaxially and rotatably embedded in the through hole. The plate surface is provided with two crosshair sight lines, which are composed of two solid lines 2.6 mm wide with a spacing of 5 mm. Several groups of small holes (18) are arranged in a straight line along both sides of the target line, and the line connecting the centers of the small holes is parallel to the target line. The fixed shaft (1) passes through the center of the crosshair and is mechanically connected to the transmission device (12); the LED light source is set on the back of the shaft scale plate (4).

2. The visualization calibration device for the focal line of an astigmatic eye according to claim 1, characterized in that: The axis scale plate (4) is made of 3mm thick light-transmitting acrylic plate, the inner diameter of the through hole is 198mm, and the minimum division value of the axis scale (16) is 1°.

3. The visualization calibration device for the focal line of an astigmatic eye according to claim 1, characterized in that: The diameter of the small hole (18) is 4.5 mm, the center-to-center distance between adjacent small holes is 15 mm, and the center-to-center distance of the small hole closest to the target line is 15 mm from the target line.

4. The visualization calibration device for the focal line of an astigmatic eye according to claim 1, characterized in that: The transmission device (12) includes an electric drive assembly, which is connected to the crosshair disk (3) via a fixed shaft (1).

5. The visualization calibration device for the focal line of an astigmatic eye according to claim 1, characterized in that: A level (17) is provided on the top of the axis scale plate (4).

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