Soft contact lens

Abstract

The invention discloses a soft contact lens. By eliminating partial high-order aberration of eyes, the definition of watching a far target when a user wears the soft contact lens is improved. Specifically, for the spherical aberration, by setting a central foot correction area and a peripheral compensation area with specific parameters, the negative power of the lens from the center to the edge is decreased progressively, the phenomenon that the negative power of the periphery of the lens is over-corrected due to the spherical aberration is avoided, and the problem that due to the spherical aberration, a light-emitting point target forms a confusion circle image on a retina focal plane, and the visual definition is affected is solved. For the coma, the negative power decreasing structures are asymmetrically arranged on the two sides of the focal power direction of the cylindrical lens, the negative power on one side of the cylindrical lens is reduced, and the problem that due to the coma, light of a luminous point enters eyes to form coma light spots, and visual interference is caused is solved.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of vision correction, in particular, to a soft contact lens for improving the clarity of a myopic soft contact lens wearer when gazing at a distant target. BACKGROUND

[0002] About the refractive defects of the eye

[0003] From the perspective of visual optics, the human eye is not a precise ideal refractor, and there are three aspects of defects that can affect the visual clarity of the eye.

[0004] (1) Defocus

[0005] Defocus refers to the fact that the focal plane of light rays from a distant target deviates from the photoreceptor layer of the retina, also known as myopia or hyperopia. Using a spherical lens to compensate for the focal length of the eye's refractive system can accurately correct the defocus defect of the eye.

[0006] (2) Astigmatism

[0007] After using a spherical lens to correct the defocus of the eye, the light rays from the distant target cannot form a focal image with consistent image positions, which is called astigmatism. Using a cylindrical lens to compensate for the focal difference between the main meridians of the eye's refractive system can accurately correct the astigmatism defect of the eye.

[0008] (3) Aberration

[0009] Aberration is divided into high-order aberration and low-order aberration. The aforementioned defocus and astigmatism are low-order aberrations, and after quantitatively compensating for low-order aberrations with ordinary spherical and cylindrical lenses, there are still residual refractive defects called high-order aberrations, which affect the visual clarity of the eye to some extent. More than a century ago, an aberrometer could be used to quantitatively test high-order aberrations, but the aberrometer was not as popular as the optometry instrument because high-order aberrations could be tested, but conventional optical lenses could not fully compensate for them.

[0010] About high-order aberration

[0011] The difference between the real information of the target and the visual imaging information of the eye is called aberration. High-order aberrations are numerous, including spherical aberration and coma, etc. The cornea of the eye accounts for 75% of the dominant refractive power, and most of the high-order aberrations come from the irregular complex shape of the corneal surface. The focal plane information formed by the refractive system of the human eye cannot be completely matched with the photoreceptor layer of the retina.

[0012] (1) Spherical aberration

[0013] The light rays of the light emitting point on the visual axis pass through the elliptical arc cornea into the pupil, and the refractive power difference between the on-axis and off-axis occurs. When the on-axis light is clearly focused on the retina, the off-axis light is focused behind the retina, and a diffuse focus image is formed around the on-axis light focus on the retina, resulting in a diffuse circular image of the light emitting point on the retinal focal plane Figure 1a and 1b The fixation field is composed of countless light emitting points, and the light rays emitted by the light emitting points form countless diffuse circles under the influence of spherical aberration, thereby affecting the visual clarity of the eye.

[0014] (2) Coma

[0015] The light rays of the light emitting point on the visual axis pass through the elliptical arc cornea into the pupil, and the refractive power difference between the on-axis and off-axis occurs. When the on-axis light is clearly focused on the retina, the off-axis light is focused behind the retina, and a diffuse focus image is formed around the on-axis light focus on the retina, resulting in a diffuse circular image of the light emitting point on the retinal focal plane Figure 2a and 2b The fixation field is composed of countless light emitting points, and the light rays emitted by the light emitting points form countless diffuse circles under the influence of spherical aberration, thereby affecting the visual clarity of the eye. SUMMARY

[0016] The present application provides a soft contact lens to solve the above-mentioned problems in the prior art.

[0017] According to the present application, a soft contact lens is provided, which comprises a foot correction area at the geometric center of the lens for spherical aberration compensation and a compensation area at the periphery of the foot correction area, wherein the diameter of the foot correction area is 2-3 mm, and the foot correction is quantified according to the refractive prescription, and the negative power of the compensation area decreases from the foot correction area to the periphery, and the total decrease is -0.50D to -0.75D.

[0018] Optionally, the compensation area is 3-6 de-focus rings, each de-focus ring has a width of 0.4-0.8 mm, and the negative power of adjacent de-focus rings decreases by -0.10D to -0.20D.

[0019] Optionally, the compensation area is a non-spherical negative power decreasing area with a width of 2.2-2.5 mm, and the total decrease is -0.50D to -0.75D.

[0020] Optionally, the soft contact lens further comprises an asymmetric negative power decreasing structure on both sides of the cylindrical focal power direction for coma compensation, and the total decrease is -0.15D to -0.30D.

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

[0022] Optionally, two sides of the cylindrical focal power are divided into A side and B side, and the B side is the positive focal power lower side determined in the corneal topography, and the negative focal power decrement is only set in the B side.

[0023] Optionally, in the case that the compensation zone is 3 to 6 defocus rings, the asymmetric negative focal power decrement structure is realized by the defocus rings.

[0024] Optionally, in the case that the compensation zone is a negative aspherical focal power decrement zone, the asymmetric negative focal power decrement structure is realized by the negative aspherical focal power decrement zone.

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

[0026] The soft contact lens according to the present application improves the clarity of gazing at a far target when the soft contact lens is worn by eliminating part of the high-order aberration of the eye (including spherical aberration and coma). Specifically, for spherical aberration, by setting a central sufficient correction zone and a peripheral compensation zone with specific parameters, the negative focal power of the lens is decreased from the center to the edge, avoiding overcorrection of the negative focal power of the lens periphery due to spherical aberration, and solving the problem of the formation of a diffuse circle image of a light emitting point target on the retinal focal plane, affecting the visual clarity. For coma, the negative focal power decrement structure is asymmetrically arranged on both sides of the cylindrical focal power, reducing the negative focal power on one side of the cylinder, and solving the problem of the formation of a comet-shaped light spot after the light of a light emitting point enters the eye, causing visual disturbance. BRIEF DESCRIPTION OF DRAWINGS

[0027] Other details and advantages of the present application 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 limiting of the present application, which will be described in detail below with reference to the accompanying drawings, in which:

[0028] Figure 1a and 1b respectively show the corneal topography and incident light focal error analysis of spherical aberration.

[0029] Figure 2a and 2b respectively show the corneal topography and incident light focal error analysis of coma.

[0030] Figure 3 shows the virtual ellipse of the cornea and spherical aberration.

[0031] Figure 4 shows the peripheral overcorrection caused by spherical aberration.

[0032] Figure 5 shows the coronal view of spherical aberration compensation.

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

[0034] Figure 7 A schematic diagram of peripheral overcorrection due to coma is shown.

[0035] Figure 8 A coronal view of coma compensation is shown. DETAILED DESCRIPTION

[0036] Embodiments of the present application are described herein below with reference to the accompanying drawings. In the following description, numerous specific details are set forth in order to provide a thorough understanding of the present application. It will be apparent, however, to one skilled in the art, that the present application can be practiced without some or all of these specific details. In other instances, well known process steps have not been described in detail in order not to unnecessarily obscure the present application. In addition, it is to be understood that the present application is not limited in its application to the particular implementation, implementations, conditions, or environments of operation illustrated herein, which are provided for descriptive purposes solely. It is to be understood that the application is not limited in its application to the details of construction and the arrangement of components set forth in the following description or illustrated in the drawings. Rather, the application is capable of other embodiments and of being practiced or being carried out in various ways.

[0037] 1. Spherical aberration compensation

[0038] (1) Analysis of the magnitude of spherical aberration

[0039] The trajectory of the sagittal shape of the cornea can be virtually extended as an ellipse, resulting in a comparative focal power difference between the center and the periphery of the cornea. The average difference between the focal power of the paraxial light and the focal power of the extra-axial light emitted by the light emitting point is the spherical aberration, and the magnitude f of the spherical aberration can be calculated as follows.

[0040] 1) The average eccentricity e value of the ellipse of the measured cornea of Chinese people is about 0.39, and the average focal power f1 of the geometric center A of the cornea is about 43.00D. Given that the comprehensive refractive index n of the corneal lens is 1.3375, the average curvature radius r1 of the geometric center of the cornea is about:

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

[0042] 2) According to the above measurement results, the virtual semi-major axis a of the corneal ellipse is about 9.28mm, and the semi-minor axis b is about 8.54mm Figure 3 ).

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

[0044] 3) The average radius of the known pupil light field in the contact lens layer is about 4mm according to the measured parameters of the eye. The angle θ between BO and the semi-major axis a of the ellipse can be calculated as follows, where B is the point 4mm away from the corneal geometric center A and the straight line from B to the ellipse center O.

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

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

[0047] r2 = (a 2 × sin θ 2 +b 2 × cos θ 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 the amount of corneal spherical aberration

[0050] The amount of spherical aberration f is the difference between the average focal length f1 of the corneal geometric center and the focal length f2 of the incident light at the pupil margin

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

[0052] (2) Compensation of spherical aberration

[0053] 1) Qualitative compensation of spherical aberration

[0054] The pathology of myopia is that the positive focal length of the eye is too large, so a negative lens is chosen to offset the positive focal length of the eye. However, due to spherical aberration, the positive focal length of the corneal center is the largest, and the positive focal length decreases from the corneal center to the periphery, while the negative focal length of the corrective lens is approximately the same from the center to the edge. When the corrective negative lens just offsets the positive focal length of the corneal center, the negative lens at the periphery of the lens will be greater than the positive focal length at the edge of the cornea, showing overcorrection of the negative focal length, so the essence of spherical aberration compensation is to decrease the negative focal length of the lens from the center to the edge. Figure 4

[0055] 2) Quantitative compensation of spherical aberration

[0056] Based on the calculated value of corneal spherical aberration, trial and error correction is performed, and the clinical verification of the correction result is performed using an aberrometer. The results suggest that the actual value of corneal spherical aberration is much smaller than the calculated value. The main reasons for this are analyzed as follows.

[0057] ① The conventional spherical and cylindrical optical lens is used to correct the low-order aberration of the eye, and part of the high-order aberration is also corrected. ​

[0058] ②The pupil diameter of the spectacle eye is not always at the maximum value when looking far, so it cannot always show the theoretical spherical aberration value.

[0059] ③The corneal eccentricity e value and the corneal geometric center curvature power used for modeling calculation are the population mean values, and the spherical aberration of a certain number of subjects is lower than the calculated value.

[0060] Based on the above reasons, the trial and error results show that the spherical aberration compensation value of 1 / 3 of the calculated value is sufficient for most spectacle wearers, about 0.50D to 0.75D.

[0061] 3) Spherical aberration compensation method

[0062] ①Central sufficient correction area

[0063] Both eyes must maintain the resting eye position and moderate tonic accommodation when looking far to meet the binocular fusion requirements, so the lens geometric center 2mm to 3mm diameter area is quantitatively sufficient according to the refraction test results.

[0064] ②Peripheral compensation area

[0065] From the central sufficient correction area to the periphery, 3 to 6 de-focusing rings are set, with a ring width of about 0.4mm to 0.8mm, each ring decreasing by -0.10D to -0.20D, or a 2.2mm to 2.5mm wide negative aspherical power decreasing area is set from the central sufficient correction area to the periphery ( Figure 5 ), with a total decrease of about -0.50D to -0.75D.

[0066] 2. Coma aberration compensation

[0067] (1) Qualitative coma aberration compensation

[0068] Coma evolves from corneal astigmatism, which shows that there is a focal difference in two principal meridians of the corneal surface, that is, when a spherical negative lens is used to exactly offset the myopic positive power of one meridian, the other meridian is in a state of undercorrected myopic positive power. Usually, a negative cylindrical lens is used to offset the undercorrected myopic astigmatism positive power ( Figure 6 ) of one meridian.

[0069] Coma, on the other hand, shows that the curvature on both sides of one meridian is not consistent, resulting in the complete correction of one side when a standard negative cylindrical lens is used to offset the undercorrected astigmatism positive power of one meridian, and the other side is in a state of myopic overcorrection, which requires an appropriate reduction in the negative power of one side of the cylindrical lens ( Figure 7 ).

[0070] (2) Quantitative coma aberration compensation

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

[0072] (3) Compensation method of coma

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

[0074] 2) It should be clear that the meridian direction of the astigmatism axis has no cylindrical focal power, and the meridian direction orthogonal to the cylindrical axis is the cylindrical focal power direction.

[0075] 3) The cylindrical focal power direction is divided into A and B sides from the geometric center of the lens, and the side with lower positive focal power is determined as the B side according to the corneal topography. The cylindrical power on this side is appropriately reduced. The method is to use the de-focusing ring or aspherical de-focusing area for compensating spherical aberration, and the asymmetrically decreasing cylindrical negative power is-0.15D to-0.30D. Figure 8 )。

[0076] In summary, through the theoretical analysis and clinical verification of the inventor, a new type of soft contact lens is designed, which improves the clarity of gazing at a far target when wearing a soft contact lens by eliminating part of the high-order aberration of the eye (including spherical aberration and coma). Specifically, for spherical aberration, by setting a central foot correction area and a peripheral compensation area with specific parameters, the negative power of the lens from the center to the edge is decreased, which avoids the overcorrection of the negative power of the lens periphery caused by spherical aberration, and solves the problem of diffuse circular image of the light point target on the retinal focal plane caused by spherical aberration, which affects the visual clarity. For coma, the negative power decreasing structure is asymmetrically arranged on both sides of the cylindrical focal power direction, which reduces the negative power on one side of the cylindrical lens, and solves the problem of comet-shaped light spot formed by the light rays of the light point after entering the eye, which causes visual disturbance caused by coma.

[0077] Although the present application has been disclosed with reference to the preferred embodiments above, the present application is not limited thereto. Any modifications and changes made by those skilled in the art without departing from the spirit and scope of the present application shall be included in the protection scope of the present application, and therefore the protection scope of the present application shall be limited by the scope defined in the claims.

Claims

1. A soft contact lens, characterized by, The soft contact lens comprises a footpad area for spherical aberration compensation located at the geometric center of the lens and a compensation area located at the periphery of the footpad area, wherein the diameter of the footpad area is 2-3 mm, and the footpad area is quantitatively corrected according to the refractive prescription, and the power of the compensation area decreases from the footpad area to the periphery, and the total decrease is -0.50D to -0.75D.

2. The soft contact lens of claim 1, wherein, The compensation area is 3-6 de-powering rings, each de-powering ring has a width of 0.4-0.8 mm, and the adjacent de-powering rings have a decrease of -0.10D to -0.20D.

3. The soft contact lens of claim 1, wherein, The compensation area is a non-spherical power decreasing area with a width of 2.2-2.5 mm, and the total decrease is -0.50D to -0.75D.

4. The soft contact lens of any one of claims 1 to 3, wherein, The soft contact lens further comprises an asymmetric power decreasing structure for coma aberration compensation located on both sides of the cylindrical power direction, and the total decrease is -0.15D to -0.30D.

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

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

7. The soft contact lens of claim 4, wherein, In the case where the compensation area is 3-6 de-powering rings, the asymmetric power decreasing structure is realized by the de-powering rings.

8. The soft contact lens of claim 4, wherein, In the case where the compensation area is a non-spherical power decreasing area, the asymmetric power decreasing structure is realized by the non-spherical power decreasing area.

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