Soft contact lens

Abstract

The utility model discloses a kind of soft contact lenses. By eliminating the part of high-order aberration of eye, improve the definition when wearing soft contact lens gazes far target. Specifically, for spherical aberration, by setting the center foot correction area and peripheral compensation area with specific parameters, the negative power of lens from center to edge decreases, avoid the negative power of lens periphery overcorrection caused by spherical aberration, solve the problem that light emitting point target forms diffuse circle image on retina focal plane caused by spherical aberration, affect visual definition. For coma, negative power decreasing structure is asymmetrically arranged on both sides of cylindrical focal power, reduces the negative power of cylindrical side, solves the problem that light emitting point light forms comet-shaped light spot after entering eye, causes visual disturbance caused by coma.

Description

Technical Field

[0001] This utility model relates to the field of vision correction technology, and more specifically, to a soft contact lens for improving the clarity of focusing on distant targets when wearing a soft contact lens for myopia. Background Technology

[0002] Regarding refractive defects of the eye

[0003] From the perspective of visual optics, the human eye is not a perfectly accurate refractive body, and there are roughly three defects that may affect the visual clarity of the eye.

[0004] (1) Defocus

[0005] Defocus refers to the phenomenon where the focal plane of light rays from distant objects deviates from the level of the photoreceptor cells on the retina; it is also known as myopia or hyperopia. Using spherical lenses to compensate for the focal length of the eye's refractive system can precisely correct this defocus defect.

[0006] (2) Defocusing

[0007] When a spherical lens is used to correct defocusing of the eye, the light rays from distant objects cannot form a focused image with consistent image position, a condition known as astigmatism. Cylindrical lenses, by compensating for the focal aberration between the principal meridians of the eye's refractive system, can precisely correct the eye's astigmatism.

[0008] (3) Aberrations

[0009] Aberrations are classified into higher-order aberrations and lower-order aberrations. Defocus and defocus, as mentioned above, are lower-order aberrations. After quantitatively compensating for lower-order aberrations with ordinary cylindrical lenses, the remaining refractive defects are called higher-order aberrations, which affect the visual acuity of the eye to a certain extent. More than a century ago, aberrometers could be used to quantitatively test higher-order aberrations, but aberrometers were not as popular as optometry instruments because while higher-order aberrations could be measured, they could not be adequately compensated for using conventional optical lenses.

[0010] Regarding higher-order aberrations

[0011] The difference between the true information of the object being viewed and the visual image information formed by the eye is called aberration. There are many types of higher-order aberrations, mainly including spherical aberration and coma. The cornea accounts for 75% of the dominant refractive power of the eye, and most higher-order aberrations originate from the irregular and complex shape of the corneal surface. This results in the focal plane information formed by the human eye's refractive system not being completely synchronized with the photoreceptor cells of the retina.

[0012] (1) Spherical difference

[0013] Light rays from a luminous point on the visual axis enter the pupil through the elliptical curved cornea, where a difference in refractive power exists between paraxial and off-axis focal powers. While paraxial light focuses clearly on the retina, off-axis light focuses behind the retina, creating a diffuse focal image around the paraxial light's focal point on the retina. This results in the luminous point target forming a circle of confusion on the retinal focal plane. Figure 1a and 1b The field of vision is composed of countless light-emitting points. The light emitted by these points enters the eye and, due to spherical aberration, forms countless circles of confusion, thus affecting the visual clarity of the eye.

[0014] (2) Coma aberration

[0015] Light rays from the luminous point on the visual axis enter the pupil through the asymmetrical curvature of the cornea, inducing a difference in refractive power between the on-axis and off-axis focal lengths. While the on-axis light focuses at the retinal level to form a relatively bright focal point, the off-axis light focuses behind the retina, creating a trailing diffuse light effect beside the focal point of the on-axis light on the retina, resembling a comet, hence the term coma. Figure 2a and 2b The field of vision consists of countless luminous points. When the light emitted from these points enters the eye, it forms countless coma-shaped spots under the influence of coma, thus causing visual interference to the eye. Summary of the Invention

[0016] The starting point of this invention is to provide a soft contact lens, thereby solving the above-mentioned problems existing in the prior art.

[0017] According to this utility model, a soft contact lens is provided, the soft contact lens including a foot correction zone located at the geometric center of the lens for spherical aberration compensation and a compensation zone located around the foot correction zone, wherein the diameter of the foot correction zone is 2mm to 3mm, and the foot correction is quantitatively performed according to the refractive prescription, and the negative power of the compensation zone decreases from the foot correction zone to the periphery, with a total decrease of -0.50D to -0.75D.

[0018] Optionally, the compensation zone consists of 3 to 6 focal reduction rings, each with a width of 0.4 mm to 0.8 mm, and the negative focal reduction of adjacent focal reduction rings is -0.10D to -0.20D.

[0019] Optionally, the compensation zone is an aspherical negative focal length reduction zone with a width of 2.2 mm to 2.5 mm, and the total reduction is -0.50D to -0.75D.

[0020] Optionally, the soft contact lens further includes an asymmetric negative power reduction structure located on both sides of the cylindrical focal force direction for coma compensation, with a total reduction of -0.15D to -0.30D.

[0021] Optionally, in the asymmetric negative power decreasing structure, the cylindrical lens focal force is orthogonal to the corneal astigmatism axis.

[0022] Optionally, the two sides of the cylindrical lens focal power are divided into side A and side B. Side B is the side with lower positive focal power as determined by the corneal topography map, and the decrease in negative focal power is only set on side B.

[0023] Optionally, when the compensation zone consists of 3 to 6 reducing rings, the asymmetric negative focal length reduction structure is achieved through the reducing rings.

[0024] Optionally, when the compensation region is an aspherical negative focal length reduction region, the asymmetric negative focal length reduction structure is implemented through the aspherical negative focal length reduction region.

[0025] The soft contact lens according to this invention has at least the following advantages:

[0026] This invention relates to a soft contact lens that improves the clarity of focusing on distant targets by eliminating some higher-order aberrations of the eye (including spherical aberration and coma). Specifically, for spherical aberration, a central full-correction zone and a peripheral compensation zone with specific parameters are set up to reduce the negative power of the lens from the center to the edge, avoiding overcorrection of the peripheral negative power of the lens caused by spherical aberration. This solves the problem of luminous targets forming a circle of confusion on the focal plane of the retina due to spherical aberration, which affects visual clarity. For coma, a negative power reduction structure is set asymmetrically on both sides of the cylinder lens power, reducing the negative power on one side of the cylinder lens. This solves the problem of luminous light forming a coma-shaped spot after entering the eye due to coma, which causes visual interference. Attached Figure Description

[0027] Other details and advantages of this utility model will become apparent from the detailed description provided below. It should be understood that the following drawings are merely schematic and not drawn to scale, and therefore should not be considered as limitations on this utility model. The following detailed description will refer to the drawings, in which:

[0028] Figure 1a and 1b Corneal topography and incident focal aberration analysis of spherical aberration are shown separately.

[0029] Figure 2a and 2b Corneal topography and incident light focal aberration analysis of coma are shown respectively.

[0030] Figure 3 The virtual ellipse and spherical aberration of the cornea are shown.

[0031] Figure 4 This illustrates peripheral overcorrection caused by spherical aberration.

[0032] Figure 5 The coronal plane diagram of spherical aberration compensation is shown.

[0033] Figure 6 A schematic diagram of astigmatism correction is shown.

[0034] Figure 7 This illustrates the overcorrection on one side of the periphery caused by coma.

[0035] Figure 8 The coronal plot with coma compensation is shown. Detailed Implementation

[0036] Embodiments of the present invention are described below with reference to the accompanying drawings. In the following description, numerous specific details are set forth to enable those skilled in the art to more fully understand and implement the present invention. However, it will be apparent to those skilled in the art that implementations of the present invention may not include some of these specific details. Furthermore, it should be understood that the present invention is not limited to the specific embodiments described. Rather, the present invention can be conceived to be implemented with any combination of the features and elements described below, regardless of whether they relate to different embodiments. Therefore, the following aspects, features, embodiments, and advantages are for illustrative purposes only and should not be construed as elements or limitations of the claims unless expressly set forth in the claims.

[0037] 1. Ball difference compensation

[0038] (1) Quantitative analysis of spherical aberration

[0039] The cornea can be virtually elliptical based on its sagittal morphological trajectory, resulting in a comparative focal difference between the corneal center and periphery. The average difference between the paraxial and off-axis optical powers emitted by the luminous point is spherical aberration, and the value of spherical aberration f can be calculated as follows.

[0040] 1) The measured average eccentricity e of the cornea in Chinese individuals is approximately 0.39, and the measured average power f1 at the geometric center A of the cornea is approximately 43.00D. Given that the overall refractive index n of the corneal lens is 1.3375, the average radius of curvature r1 at the geometric center of the cornea is approximately:

[0041] (n-1) / f1=0.3375 / 43=0.00785(m)=7.85(mm).

[0042] 2) Based on the above measurement results, the semi-major axis a of the virtual corneal ellipse can be calculated to be approximately 9.28 mm, and the semi-minor axis b to be approximately 8.54 mm. Figure 3 ).

[0043] Verification: Corneal geometric center radius of curvature r1 = b 2 / a=8.54 2 / 9.28=7.85(mm).

[0044] 3) Based on the measured parameters of the eye, it can be calculated that the average radius of the entrance pupil's visual field at the contact lens level is about 4mm. Draw a straight line from point B, which is 4mm away from the geometric center of the cornea, to the center of the ellipse O. Then, the angle θ between BO and the semi-major axis a of the ellipse can be calculated as follows.

[0045] tanθ=AB / a=4 / 9.28=0.43θ=23.3°

[0046] 4) The radius of curvature r2 and curvature focal length f2 at point B can be calculated as follows.

[0047] r2=(a 2 ×sinθ 2 +b 2 ×cosθ 2 ) 3 / 2 / ab=649.52 / 79.25=8.2(mm)

[0048] f2=(n-1) / r2=0.3375 / 8.2=41.15(D)

[0049] 5) Calculation of corneal spherical aberration

[0050] The value of spherical aberration, f, is the difference between the average focal power f1 at the geometric center of the cornea and the focal power f2 of the incident light ray at the pupillary margin.

[0051] f=f1-f2=43-41.15=1.85(D)

[0052] (2) Compensation for ball difference

[0053] 1) Qualitative nature of ball difference compensation

[0054] The pathology of myopia is an excessive positive focal length in the eye, so negative lenses are used to counteract this positive focal length. However, due to spherical aberration, the positive focal length is greatest at the center of the cornea, decreasing towards the periphery. Since the negative focal length of the corrective lens remains roughly the same from the center to the edge, when the corrective negative lens exactly counteracts the positive focal length at the center of the cornea, the negative focal length at the periphery will be greater than the positive focal length at the edge, resulting in overcorrection. Therefore, spherical aberration compensation essentially involves decreasing the negative focal length of the lens from the center to the edge. Figure 4 ).

[0055] 2) Quantitative calculation of spherical aberration compensation

[0056] Based on the calculated value of spherical aberration, trial-and-error correction was performed, and the correction results were clinically verified using an aberrometer. The results indicated that the actual value of spherical aberration was much smaller than the calculated value. The main reasons are analyzed as follows.

[0057] ① While using conventional spherical cylindrical optical lenses to correct low-order aberrations of the eye, some high-order aberrations are also corrected.

[0058] ②When looking at distant objects, the pupil diameter of the eye wearing glasses is not always at its maximum value, so it cannot continuously display the theoretically calculated spherical aberration value.

[0059] ③ The corneal eccentricity e-value and corneal geometric center curvature diopter used for modeling calculations are the median values ​​in the population, and the spherical aberration of a certain number of test eyes is lower than the calculated values.

[0060] Based on the above reasons, the trial and error results suggest that a spherical aberration compensation value of 1 / 3 of the calculated value is sufficient for the vast majority of people who wear glasses, which is approximately 0.50D to 0.75D.

[0061] 3) Methods for compensating for ball difference

[0062] ① Central foot orthotic area

[0063] In order to meet the fusion requirements of both eyes when looking at distant objects, the eyes must maintain a resting eye position and moderate tension accommodation. Therefore, the 2mm to 3mm diameter area of ​​the lens geometric center is quantitatively and fully corrected according to the refractive test results.

[0064] ② Surrounding compensation area

[0065] From the center foot correction area outwards, set 3 to 6 reduction rings, each approximately 0.4mm to 0.8mm wide, with each ring decreasing by -0.10D to -0.20D. Alternatively, from the center foot correction area outwards, set a 2.2mm to 2.5mm wide aspherical negative focal length reduction zone. Figure 5 The total amount decreases by approximately -0.50D to -0.75D.

[0066] 2. Coma Compensation

[0067] (1) Qualitative analysis of coma compensation

[0068] Coma evolves in corneal astigmatism, which manifests as focal aberration along the two principal meridians of the corneal surface. Specifically, when a negative spherical lens precisely cancels out the myopic positive focal power along one meridian, the other meridian remains undercorrected for myopic positive focal power. Typically, a negative cylindrical lens is used alone to cancel out the undercorrected myopic astigmatic positive focal power along the uncorrected meridian. Figure 6 ).

[0069] Coma manifests as inconsistent curvature on both sides of a meridian. This means that when a standard negative cylinder lens is used to compensate for undercorrected meridional astigmatism, after one side is fully corrected, the other side remains in an overcorrected state of myopia. Therefore, it is necessary to appropriately reduce the negative power on the cylinder lens side. Figure 7 ).

[0070] (2) Quantitative analysis of coma compensation

[0071] The magnitude of coma is related to two factors: the amount of astigmatism and spherical aberration of the cornea. In the process of correcting astigmatism and compensating for spherical aberration in the eye, a certain amount of coma has already been compensated. Therefore, the compensation requirement for coma is only about 0.15D to 0.30D.

[0072] (3) Methods for compensating for coma

[0073] 1) The astigmatic axis of the eye needs to be located in advance.

[0074] 2) It should be clear that there is no cylindrical focal force in the meridional direction where the astigmatic axis is located, and the meridional direction orthogonal to the cylindrical focal force direction is the cylindrical focal force direction.

[0075] 3) Divide the cylindrical lens power into two sides, A and B, from the lens geometric center. Determine the side with lower positive focal power based on the corneal topography as side B, and appropriately reduce the cylindrical lens power on that side. This is done by using a focal reduction ring to compensate for spherical aberration or an aspherical focal reduction area to asymmetrically reduce the negative cylindrical lens power by an amount ranging from -0.15D to -0.30D. Figure 8 ).

[0076] In summary, through theoretical analysis and clinical verification, the inventors designed a novel soft contact lens that improves the clarity of focusing on distant targets when wearing soft contact lenses by eliminating some higher-order aberrations of the eye (including spherical aberration and coma). Specifically, for spherical aberration, by setting a central full-correction zone and a peripheral compensation zone with specific parameters, the negative power of the lens decreases from the center to the edge, avoiding overcorrection of the peripheral negative power of the lens caused by spherical aberration, and solving the problem of luminous point targets forming a circle of confusion image on the focal plane of the retina due to spherical aberration, which affects visual clarity. For coma, an asymmetrical negative power decreasing structure is set on both sides of the cylinder lens focal power, reducing the negative power on one side of the cylinder lens, and solving the problem of luminous point light forming a coma-shaped spot after entering the eye due to coma, which causes visual interference.

[0077] Although the present invention has been disclosed above with reference to preferred embodiments, it is not limited thereto. Any modifications and alterations made by those skilled in the art without departing from the spirit and scope of the present invention should be included within the protection scope of the present invention. Therefore, the protection scope of the present invention should be determined by the scope defined in the claims.

Claims

1. A soft contact lens, characterized by, The soft contact lens includes a foot correction zone located at the geometric center of the lens for spherical aberration compensation and a compensation zone located around the foot correction zone. The diameter of the foot correction zone is 2 mm to 3 mm, and it provides quantitative foot correction according to the refractive prescription. The negative power of the compensation zone decreases from the foot correction zone to the periphery, with a total decrease of -0.50D to -0.75D.

2. The soft contact lens of claim 1, wherein, The compensation zone consists of 3 to 6 focal reduction rings, each with a width of 0.4 mm to 0.8 mm, and the negative focal reduction of adjacent focal reduction rings is -0.10D to -0.20D.

3. The soft contact lens of claim 1, wherein, The compensation zone is an aspherical negative focal length reduction zone with a width of 2.2mm to 2.5mm, and a total reduction of -0.50D to -0.75D.

4. The soft contact lens of any one of claims 1 to 3, wherein, The soft contact lens also includes an asymmetric negative power reduction structure located on both sides of the cylindrical focal force direction for coma compensation, with a total reduction of -0.15D to -0.30D.

5. The soft contact lens of claim 4, wherein, In the asymmetric negative power decreasing structure, the cylindrical lens focal force is orthogonal to the corneal astigmatism axis.

6. The soft contact lens of claim 4, wherein, The cylindrical lens is divided into two sides, A and B, with side B being the side with lower positive focal power as determined by the corneal topography. The decrease in negative focal power is only set on side B.

7. The soft contact lens of claim 4, wherein, When the compensation zone consists of 3 to 6 reducing rings, the asymmetric negative focal length reduction structure is achieved through the reducing rings.

8. The soft contact lens of claim 4, wherein, When the compensation region is an aspherical negative focal length reduction region, the asymmetric negative focal length reduction structure is achieved through the aspherical negative focal length reduction region.

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