Ophthalmic lens customized for wearer and preparation method thereof
Technical Field
The invention relates to a design method of a personalized lens for eyes, in particular to a design method of a lens and a processed lens by considering the pupil position of a human eye and the inclination factor of the lens.
Background
It is well known in the art that eyeglasses are used for the correction of visual defects. The visual defects of the spectacle wearer are described by an prescription provided by an ophthalmologist or optometrist, giving the desired parameters of the power of the lens to be worn, the power of astigmatism, the direction of astigmatism, the refractive power of the lens material, etc. The lens maker designs and manufactures the lens according to the prescription of optometry, and finally uses a lens tester to test the average diopter and the astigmatism of the lens in a small area of a point specified by the industry.
In fact, when the eyes watch objects, the sight line moves along with the positions of the objects, eyeballs of the glasses wearer rotate, and the glasses can watch the objects through different areas of the lenses. Because the lens has certain thickness, the curvatures of the front refracting surface and the rear refracting surface are different, a small area through which a sight line passes is equivalent to a small lens, the small lenses are different, and the refracting imaging states also belong to different off-axis object imaging states. Therefore, the diopter power (refractive power of the lens) actually perceived by the human eye varies with the region through which the line of sight passes, and varies differently in both the meridional and sagittal directions. That is, not only the average diopter power in oblique view (oblique diopter power) but also the diopter power in normal view (paraxial diopter power) change, but also additional astigmatism (oblique astigmatism) occurs.
The path of the human eye's sight line passing through the lens, the refractive imaging of the different zones of the lens corresponding to the lenslets, the refractive state of which is closely related to the surface shape and thickness of the lens, the inclination of the lens in the vertical and horizontal directions and the position of the pupil of the human eye, so that the diopter actually perceived by the human eye is also closely related to these factors. These factors are determined by the degree of eyeglasses required by the wearer to correct the visual defect, the shape of the wearer's face, and the shape of the frame selected.
Obviously, in order to obtain optimal visibility, attention must be paid to the refractive power in the worn state of the lens, the design and inspection of which is carried out according to the individual needs of each wearer. However, the prior art ophthalmoscopes, including lensometers, hartmann detection methods of Class Plus surface measuring instruments of the company rotex, and lambertian grating test methods, do not consider the rotation of the eyeballs of human eyes, nor do they combine the lenses with the pupils of human eyes for detection. In terms of lens design, chinese patent for invention (CN 103123420B) discloses a method of using the lens-eye pupil as an optical system to obtain the spherical power distribution and the cylindrical power distribution of the lens, which calculates the positions and the corresponding curvatures on the front and rear surfaces of the lens through which the line of sight passes with respect to the double-sided free-form surface. Chinese invention patent CN102422201 discloses a method for generating shape data of a spectacle lens capable of obtaining a good visual field even if the lens is inserted into a frame having a large front view angle. Neither of the above two patents has indicated the off-axis imaging characteristics of the small regions as lenslets in oblique viewing of the human eye and the design methods suitable for the same. Chinese patent CN 102419482B discloses a double-sided aspheric myopic spectacle lens designed by using optical design software ZEMAX as a platform, which considers the strabismus astigmatism of the lens as one of the optimization conditions, but does not relate to the tilt condition of the lens after the wearer wears the spectacles. Chinese patent publication No. CN 1511270 discloses a method of designing an ophthalmic lens taking into account eye movement, and also does not relate to the tilt of the lens.
Disclosure of Invention
The invention provides an ophthalmic lens which can prevent the appearance of large diopter error and astigmatism in the squint state of a lens wearer and has good visual field and comfortable feeling and a preparation method thereof, aiming at the defects that the prior personalized ophthalmic lens only considers the visual defects of the lens wearer and does not relate to the surface shape of the lens wearer and the defects of the selected characteristics of a lens frame.
The technical scheme for realizing the aim of the invention is to provide a preparation method of an ophthalmic lens customized for a lens wearer, which comprises the following steps:
(1) performing an prescription for a wearer of a customized ophthalmic lens, the prescription comprising the following parameters: diopter value D for representing lens refractive power required by custom-fitted glasses0The refractive index of the lens material to be processed, the spectacle lens is arranged in a selected spectacle frame to be made into spectacles, and the inclination angle of the lens after the wearer wears the spectacles is adjusted; the tilt angles include vertical and horizontal tilt angles of the lens, and pupil position; the pupil position is the distance from the intersection point of the sight line and the lens to the pupil when the wearer looks straight;
(2) establishing an evaluation model according to the pupil position, the lens inclination angle and the lens rise data to be evaluated provided by the prescription of optometry to obtain the strabismus diopter D of the evaluation resultrAnd strabismus astigmatism Cr(ii) a The establishment method of the evaluation model comprises the following steps: calculating a path through which a principal ray entering a pupil of a human eye in a certain visual angle direction passes, the position of an intersection point of the principal ray and the front and back surfaces of the lens, and curvatures of a principal normal, an incident angle, a refraction angle, a meridian plane, a sagittal plane, a meridian direction and a sagittal direction at the corresponding intersection point by adopting a curved differential geometry method and through ray tracing; respectively obtaining the positions of the meridional image points and the sagittal image points according to the principle of off-axis beamlet imaging, and further respectively obtaining the squint diopter D of the human eye sight in the corresponding visual angle directionrAnd strabismus astigmatism Cr(ii) a The strabismus diopter DrThe mean value of the meridional and sagittal direction diopters determined from the positions of the meridional and sagittal image points; the strabismus astigmatism CrThe absolute value of the difference between the dioptres in the meridional and sagittal directions determined from the positions of the meridional and sagittal image points;
(3) according to prescription of optometryProvided diopter D0Selecting the spherical curvatures of the front surface and the rear surface of the lens to be processed and the central thickness of the lens, wherein the front surface and the rear surface are designed to be spherical surfaces to obtain the rise data of the initial lens; taking the rise data of the initial lens as the rise data of the lens to be evaluated, and adopting the evaluation model in the step (2) to evaluate under the condition that the inclination angle of the lens is 0 to obtain the evaluation result of the initial lens, namely the strabismus diopter DrAnd strabismus astigmatism Cr(ii) a To have a 35 degree line of sight at the eye's angle of view (D)r-D0)/D0I is not more than 0.125 and CrNot more than 0.125| D0I is a target value, and aspheric surface optimization design is carried out on the initial lens to obtain rise data of the aspheric surface lens;
(4) taking the rise data of the aspheric lens obtained in the step (3) as the rise data of the lens to be evaluated, adopting the evaluation model in the step (2) to evaluate according to the lens inclination angle value provided by the prescription, and according to the evaluation result, taking the diopter at the central sight line as consistent with the prescription, and in the sight line range of 30 degrees of the human eye visual angle, deviating the percentage of the strabismus diopter (D)r-D0)/D0| is not more than 0.125, strabismus astigmatism CrNot more than 0.125| D0I is a target value, and the rise data of the aspheric lens is compensated and designed to obtain asymmetric lens rise data;
(5) and processing the lens according to the rise data of the obtained asymmetric curved lens to obtain the customized ophthalmic lens for the wearer.
In the technical scheme of the invention, the aspheric lens designed in the step (3) is a single-sided aspheric lens of the back surface or the front surface, and can also be a double-sided aspheric lens of the front surface and the back surface.
The asymmetric lens rise data provided by the invention is based on the rise data of the aspheric lens obtained in the step (3), and then a rise compensation value is added; the rise compensation value is obtained by adopting an asymmetric compensation method and a diopter compensation method at the central sight.
Specifically, the rise compensation value obtained by the asymmetric compensation method can be calculated according to the following formula:
Zc(x,y)=bx(x±xd)3+by(y+yd)3,
wherein, bx、byThe coefficients of the transverse cubic term and the longitudinal cubic term are respectively; x is the number ofdRespectively taking positive and negative signs to move towards the temporal side according to the difference of the left mirror and the right mirror; y isdIn millimeters of longitudinal movement.
The diopter compensation method at the central sight line is a rise compensation value obtained by adjusting the central curvature of the front surface or the rear surface of the lens and enabling the diopter at the central sight line to be consistent with the prescription.
The technical scheme of the invention also comprises the ophthalmic lens which is prepared by the preparation method and is customized for a wearer.
Compared with the prior art, when the lenses are designed according to the technical scheme of the invention, the provided prescription of optometry not only comprises the conventional optometry parameters such as refractive index value, material refractive index and the like, but also requires the vertical and horizontal inclination angles of the lenses made by wearing the selected spectacle frame by a wearer and the distance from the intersection point of the sight line and the lenses to the pupils when the wearer looks straight, so that the vision defects of the wearer are considered in designing the lenses, the surface shape of the wearer and the selected characteristics of the spectacle frame are considered, and the lenses with the asymmetric curved surface structure are obtained by adopting a method of aspheric surface design and compensation design; after the lens provided by the invention is arranged on a spectacle frame to be made into a spectacle, a wearer can effectively reduce deviation of strabismus diopter and strabismus astigmatism in a strabismus state, the accuracy of correcting vision in different sight directions is improved, and the spectacle has good visual field and comfortable feeling.
Drawings
FIG. 1 is a side view of light entering the pupil of a human eye through a lens;
FIG. 2 is a schematic view of a wearer wearing glasses showing horizontal tilt of the lenses;
FIG. 3 is an example of refractive power evaluation of a lens under the condition of no tilt through the evaluation model provided by the present invention, and shows a graph of diopter change along with the change of the human eye visual angle in the meridian direction and the sagittal direction;
FIG. 4 is an example of refractive power evaluation of a lens under a vertical tilt condition by using the evaluation model provided by the present invention, and shows a graph of diopter change along with the change of the human eye visual angle in both the meridian and sagittal directions;
FIG. 5 is a flow chart of a design for an asymmetric-curve ophthalmic lens provided by an embodiment of the present invention;
fig. 6 shows the refractive power evaluation results of the initial lens without tilt through the spectacle-eye pupil model in embodiment 2 of the present invention, showing the changes of the strabismus diopter and strabismus astigmatism with the visual angle of the human eye in the longitudinal and transverse directions;
fig. 7 is a refractive power evaluation result of a lens designed by an aspheric surface without tilt according to the glasses-eye pupil model in embodiment 2 of the present invention, which shows changes of strabismus diopter and strabismus astigmatism along with a visual angle of a human eye in both longitudinal and transverse directions;
fig. 8 is a result of evaluating refractive power of a lens designed to be aspheric in an inclined condition through a spectacle-eye pupil model according to embodiment 2 of the present invention, which shows changes of strabismus diopter and strabismus astigmatism with a change of a visual angle of a human eye in both longitudinal and transverse directions;
fig. 9 shows the refractive power evaluation results of the lens subjected to aspheric surface and compensation design under the inclined condition by the spectacle-eye pupil model in embodiment 2 of the present invention, which shows the changes of strabismus diopter and strabismus astigmatism along with the visual angle of human eyes in the longitudinal and transverse directions;
fig. 10 shows the refractive power evaluation results of the initial lens without tilt through the spectacle-eye pupil model in embodiment 2 of the present invention, showing the changes of the strabismus diopter and strabismus astigmatism with the visual angle of the human eye in both the longitudinal and transverse directions;
fig. 11 is a result of evaluating the refractive power of a lens designed by an aspheric surface through a spectacle-eye pupil model under a tilt-free condition according to embodiment 2 of the present invention, which shows changes of strabismus diopter and strabismus astigmatism along with a visual angle of a human eye in both longitudinal and transverse directions;
fig. 12 shows the refractive power evaluation results of the lens designed by an aspheric surface under an oblique condition through the spectacle-eye pupil model in embodiment 2 of the present invention, which shows the changes of the strabismus diopter and the strabismus astigmatism with the visual angle of the human eye in the longitudinal and the transverse directions;
fig. 13 shows the refractive power evaluation results of the lens designed by aspheric surface and compensation under the inclined condition by the spectacle-eye pupil model in the invention, which shows the changes of the strabismus diopter and strabismus astigmatism along with the visual angle of the human eye in the longitudinal and transverse directions.
Detailed Description
The technical solution of the present invention is further described with reference to the accompanying drawings and examples.
Example 1:
in this embodiment, a strabismus diopter D is established according to the pupil position, the lens inclination angle and the lens rise data to be evaluated provided by the prescriptionrAnd strabismus astigmatism CrAnd the evaluation model is an evaluation result and is used for evaluating the actual refractive power of the lens when the human eyes obliquely look through the lens.
Referring to fig. 1, there is shown a schematic side view of light entering the pupil of a human eye through a lens; FIG. 1 is a view illustrating the vertical outward tilt angle of a lens mounted on a spectacle framevAngle of vision of human eye phirThe chief ray (corresponding to the line of sight) entering the pupil of a human eye at a certain viewing angle direction and the incident angle a of the path traversed on the anterior surface of the lens1Emergence angle BETA on the rear surface of the lens2。
Referring to fig. 2, a schematic diagram showing horizontal tilt of lenses after a wearer wears glasses; in the drawingsLAndRthe horizontal tilt angles of the left and right mirrors, respectively. A straight line P parallel to the eye's eye sight line and passing through the center of the front surface of the lens is taken as a Z axis of the coordinate system, and a plane passing through the center of the front surface and perpendicular to the Z axis is taken as an xy plane of the coordinate system. The surface shape vector height of the front and back surfaces of the lens is subjected to vertical and horizontal rotation through coordinate transformation in a coordinate system according to an inclination angle given by an optometry prescription; warp beamThe refractive power of the lens in different visual line directions of a wearer is evaluated by an optical system by taking the front surface vector height of the lens after coordinate transformation, the rear surface vector height of the lens after coordinate transformation plus the thickness of the lens and the eye pupil position given according to an optometry prescription as the starting point of the visual line.
In the embodiment, the surface shape of a wearer and the selected characteristics of the spectacle frame are considered, an evaluation model is established according to the pupil position, the lens inclination angle and the to-be-evaluated lens rise data provided by the prescription of optometry, and the strabismus diopter D of the evaluation result is obtainedrAnd strabismus astigmatism CrFor designing a lens; the evaluation model is as follows: calculating a path through which a principal ray entering a pupil of a human eye in a certain visual angle direction passes, the position of an intersection point of the principal ray and the front and back surfaces of the lens, and curvatures of a principal normal, an incident angle, a refraction angle, a meridian plane, a sagittal plane, a meridian direction and a sagittal direction at the corresponding intersection point by adopting a curved differential geometry method and through ray tracing; respectively obtaining the positions of the meridional image points and the sagittal image points according to the principle of off-axis beamlet imaging, and further respectively obtaining the squint diopter D of the human eye sight in the corresponding visual angle directionrAnd strabismus astigmatism Cr(ii) a The strabismus diopter DrThe mean value of the diopters in the meridian and sagittal directions determined by the positions of the meridian and sagittal image points; the strabismus astigmatism CrIs the absolute value of the difference between the dioptres in the meridional and sagittal directions determined by the meridional and sagittal image point locations.
Because the exit pupil of the optical system formed by the evaluation model provided by the invention is the eye pupil with a small aperture, the optical system images the off-axis beamlets from an object to the eye pupil along the opposite direction of the sight line according to the reversible law of the optical path, and the beam axis of the beamlets is called as the chief ray. The differential geometry method of the curved surface is used for calculating the path of the principal ray entering the pupil of the human eye, the positions of the front and rear surfaces on the lens, the principal normal, the incident angle, the refraction angle, the curvature of the meridian plane, the curvature of the sagittal plane and the curvature of the sagittal plane at the corresponding positions of the front and rear surfaces of the lens through ray tracing. Incident angle A at the front surface of the lens1(ii) a Angle of refraction BETA1Incident angle A at the back surface of the lens2(ii) a Folding deviceAngle BETA2. The meridian point position is calculated by adopting an off-axis beamlet imaging formula as shown in formula (1):
calculating the sagittal image point position according to the formula (2):
in equations (1) and (2), a is the incident angle of the chief ray on the refracting surface; BETA is refraction angle; n is a radical ofAIs the refractive index of the incident side medium; n is a radical ofBIs the refractive index of the refracting medium; t isAThe distance from an object to a refraction point of incident principal rays on the meridian plane; t isBThe distance from the refraction point to the meridian image point of the refraction main ray; sAThe distance from the object to the refraction point of the incident main ray on the sagittal plane; sBThe distance from the refraction point to the sagittal image point of the refraction main ray; rTThe radius of curvature of the refraction surface in the meridian direction at the refraction point; rsIs the radius of curvature of the refracting surface in the sagittal direction at the refraction point. Equations (1) and (2) are applied sequentially on both the front and back surfaces of the refractive surface. The refraction power diopter in the meridian direction and the sagittal direction on a certain small area of the lens can be calculated according to the meridian image point position and the sagittal image point position of the infinite object after twice refraction. The average of the refractive power in the meridional and sagittal directions is the diopter of strabismus, and the strabismus at a certain position along the radial direction r is Dr. The difference between the refractive power in the meridional and sagittal directions is strabismus, and the strabismus at a certain position along the radial direction r is Cr。
The evaluation results obtained by the evaluation model are shown in fig. 3 and 4, and the lens to be evaluated is a far vision lens having spherical front and rear surfaces and a diopter of 4. Fig. 3 is a graph of diopter change along with human eye viewing angle in the meridional and sagittal directions when the lens tilt angle is 0, and shows that at a human eye viewing angle of 35 degrees, diopter in the sagittal direction does not differ much from 4 diopter required by an optometry prescription, but diopter in the meridional direction differs by more than 1 degree from 4 diopter required by design, diopter for strabismus differs by 0.55 diopter, and astigmatism of 1 diopter exists.
In fact, the lenses of the wearer have inclination when wearing the glasses, and fig. 4 is a graph showing that the lenses are inclined outwards by 8 degrees in the vertical direction, and the diopter changes along with the change of the longitudinal visual angle of the human eyes. Obviously, in the case where the lens tilt angle is not 0 (the lens is tilted), the strabismus diopter and the strabismus astigmatism are vertically asymmetric, the diopter in the sagittal direction at the 35 ° of the upper viewing angle is 4.1 diopter, but the diopter in the meridional direction reaches 5.8 diopter, the strabismus diopter is different from the 4 diopter required for the design by 0.95 diopter, and the strabismus astigmatism of 1.7 diopter exists.
From this, it is necessary to design the monofocal glasses in consideration of the actual perceived power and astigmatism of the human eye when the eye is obliquely viewed. Further, a personalized design that takes into account the tilt of the lens after the wearer has put on the glasses is also necessary.
The present embodiment provides a design method of spectacle lenses based on the above-described established evaluation model.
Referring to FIG. 5, a flow chart of the design of an asymmetric-curve ophthalmic lens according to this embodiment is shown; the method comprises the following specific steps:
1. the spherical curvature and center lens thickness of the anterior and posterior surfaces of the lens are selected to be appropriate according to the refractive power values and material indices provided by the prescription. The front surface and the back surface are spherical surfaces and serve as initial lenses, the initial lenses are evaluated for refractive power under the condition of no inclination by adopting the evaluation model, and the change of the strabismus diopter and the strabismus astigmatism along with the change of the visual angle of human eyes is obtained.
2. And optimizing the cone coefficient and the high-order term coefficient of the aspheric surface according to the strabismus diopter and strabismus astigmatism evaluated from the initial lens, and designing the aspheric surface. The rise of the aspherical surface is determined by a functional relationship of the following formula (3):
wherein r is the radial length of the lens; c is the central curvature of the aspheric surface; k is the conic coefficient of the aspheric surface; a is2m m 2,3.. 6 is the coefficient of the aspheric high-order term. To achieve a deviation percentage of squint diopter (| (D) at a viewing angle of the human eye of 35 degreesr-D0)/D0| is not more than 0.125, strabismus astigmatism CrNot more than 0.125| D0And l is a target value, and the cone coefficient and the high-order coefficient of the aspheric surface are optimized to obtain the aspheric lens. The aspheric design may be a single-sided aspheric design of the front or back surface, or a double-sided aspheric design of the front and back surfaces.
3. Further, the designed aspheric lens is re-evaluated through an evaluation model according to the inclination angle provided by the prescription. According to the evaluation result, the diopter of the central sight line is consistent with the prescription, and the strabismus diopter deviates by percentage (D) within the sight line range of 30 degrees of the visual angle of human eyesr-D0)/D0| is not more than 0.125, strabismus astigmatism CrNot more than 0.125| D0And (ii) taking the I as a target value, and performing compensation design on the rise data of the aspheric lens to obtain the rise data of the asymmetric curved lens. And (3) the rise data of the asymmetric curved lens is the rise data of the aspheric lens obtained in the step (2) plus the compensation rise data obtained according to the compensation design method.
The compensation design method comprises asymmetric compensation and diopter compensation at the central sight line, and compensation rise data are obtained.
The asymmetry compensation value comprises cubic term values in the transverse direction and the longitudinal direction, and the rise compensation value of the cubic term is shown in formula (4):
Zc(x,y)=bx(x±xd)3+by(y+yd)3 (4)
wherein, bxIs the coefficient of the transverse cubic term, xdThe positive sign and the negative sign are respectively taken to move to the temporal side according to the difference of the left mirror and the right mirror. byCoefficient of longitudinal cubic term, ydIn millimeters of longitudinal movement.
Diopter compensation for central vision is achieved by fine-tuning the central curvature of the front or back surface of the lens.
And (3) adding the compensation rise data to the rise data of the aspheric lens obtained in the step (2) to obtain the rise data of the asymmetric curved lens. And processing the lens according to the rise data of the obtained asymmetric curved lens to obtain the customized ophthalmic lens for the wearer.
Example 2
In this embodiment, the prescription provides the following parameters: 3 diopters distance vision right lens, index 1.597. The vertical inclination angle of the lens is 7 degrees and the horizontal inclination angle is 5 degrees after the wearer wears the selected spectacle frame, and the distance from the intersection point of the sight line and the lens to the pupil is 25 mm when the wearer looks flat. According to the diopter and material refractive index provided by the prescription, the front and back surfaces are selected to be spherical surfaces as the initial lens, the back surface of the lens has the diopter of 1, the curvature radius is 597 mm, and the center thickness of the lens is 2.5 mm. Corresponding to a front surface radius of curvature of 149.5 mm.
Referring to fig. 5, lens design was performed according to the protocol provided in example 1.
The spherical curvature of the front and back surfaces of the lens and the center thickness of the lens are selected according to the refractive index value and the material refractive index provided by the prescription. The front and back surfaces are spherical surfaces as initial lenses, and the refractive power of the initial lenses is evaluated under the condition of no inclination by adopting the evaluation model provided by the embodiment 1, so that the changes of the strabismus diopter and the strabismus astigmatism along with the change of the visual angle of human eyes are obtained.
In this embodiment, the refractive power of the initial lens is evaluated by the evaluation model without tilt (tilt angle is 0), and the variation of strabismus diopter and strabismus astigmatism with the visual angle of human eyes is shown in fig. 6; the figure shows the variation of the strabismus diopter and strabismus astigmatism with the visual angle of the human eye in both the longitudinal and transverse directions.
The strabismus diopter gradually deviates from the 3 diopters required by the prescription with the increase of the visual angle of the human eye, and the strabismus diopter increases to 3.46 diopters at the visual angle of 35 degrees, the deviation value is 0.46 diopter, and the deviation percentage (D)r-D0) 0.153/D0, 0.78 diopter of strabismus astigmatism, Cr/D0=0.260。
And then, the aspheric surface of the front surface is designed. The rise of the aspherical surface is determined by formula (3):
the central curvature C of the aspheric surface is 0.006690mm-1. The conic coefficient K of the optimized aspheric surface is-6.04, and the coefficient a of the aspheric surface high-order term4=-1.5×10-7,a6=-4.1×10-11。a8=5.2×10-14a10=-8.9×10-18. The refractive power of the aspherical lens was evaluated by an evaluation model without tilt (tilt angle 0), and changes in the strabismus diopter and strabismus astigmatism according to the angle of view of the human eye were obtained as shown in fig. 7. Strabismus diopter 3.08 diopter, deviation value 0.08 diopter, deviation percentage (D) at viewing angle 35 degreesr-D0)/D00.027, 0.36 diopter of strabismus astigmatism, Cr/D00.120. The strabismus diopter deviation and strabismus astigmatism are significantly reduced, both less than 0.125 times the 3 diopters.
Further, for the designed aspheric lens, the vertical inclination angle provided according to the prescription is 7 degrees, the horizontal inclination angle is 5 degrees, re-evaluation is carried out through an evaluation model, the upper part of the lens is inclined outwards by 7 degrees, and the right side of the lens is inclined inwards by 5 degrees (right lens); the refractive power evaluation results are shown in fig. 8. The actual refractive power of the lens after the lens is inclined is greatly changed along with the change of the sight line direction of human eyes, and the diopter of the central sight line of the lens deviates from 3 diopters required by the prescription and is 3.056 diopters. The strabismus diopters in the up-down direction and the left-right direction deviate obviously asymmetrically, the upward 30-degree visual angle is 3.36 diopters, the downward 30-degree visual angle is 2.90 diopters, the nasal 30-degree visual angle is 3.30 diopters, and the temporal 30-degree visual angle is 2.97 diopters. The oblique astigmatism in the up-down and left-right directions is also obviously asymmetric, and is 0.69 diopter at the upward 30-degree view angle, 0.09 diopter at the downward 30-degree view angle, 0.62 diopter at the nasal 30-degree view angle and 0.20 diopter at the temporal 30-degree view angle. The evaluation results showed that although the designed aspherical lens satisfied both the deviation of the dioptric power and the astigmatism of strabismus in the non-tilted state, the wearer worn the spectacles with the aspherical lens largely changed the actual refractive power in strabismus, the maximum strabismus power was deviated from 0.36 diopter, the maximum strabismus astigmatism was 0.69 diopter, and the wearer felt discomfort in strabismus.
According to the evaluation results provided in the present embodiment, the sagittal height data of the lens front surface is subjected to the asymmetry compensation and the diopter compensation at the central sight line. The asymmetry compensation comprises cubic term values of a longitudinal direction and a transverse direction, and rise compensation values of the cubic terms are as follows:
Zc(x,y)=bx(x±xd)3+by(y+yd)3,
wherein the coefficient of transverse cubic term bxIs 3.2X 10-6(ii) a Transverse movement xd6.5 mm, and the right mirror adopts a negative sign; coefficient of longitudinal cubic term byIs 4.8 multiplied by 10-6Longitudinal movement ydIs 3.0 mm.
The center curvature of the front surface of the vernier lens was 0.006713mm-1To achieve diopter compensation of the central line of sight.
In this embodiment, the sagittal height data of the front surface of the aspherical lens is added to the compensated sagittal height data obtained by the asymmetric compensation and central diopter compensation design, and then the sagittal height data of the asymmetric curved lens is obtained. The refractive power of the asymmetric curved lens evaluated again by the evaluation model is shown in fig. 9. The diopter at the central vision of the lens meets the prescription requirement of 3 diopters. The strabismus diopter deviation in the up-down and left-right directions is obviously improved, 3.11 diopters are arranged at the upward 30-degree visual angle, 2.98 diopters are arranged at the downward 30-degree visual angle, 3.11 diopters are arranged at the nasal 30-degree visual angle, and 3.00 diopters are arranged at the temporal 30-degree visual angle. The strabismus in the up-down and left-right directions is obviously reduced, the upward 30-degree visual angle is 0.348 diopter, the downward 30-degree visual angle is 0.354 diopter, the nasal 30-degree visual angle is 0.374 diopter, and the temporal 30-degree visual angle is 0.326 diopter.
The evaluation results of the evaluation model showed that the wearer wearing the lens with the aspherical and compensating design had a maximum deviation of 0.12 diopter of strabismus (between 22 and 28 degrees in upward viewing angle) and a maximum of 0.374 of strabismus astigmatism, all of which were not more than 0.125| D in a viewing range of 30 degrees in viewing angle00.375 diopters. Can ensure that a wearer does not feel uncomfortable when looking obliquely.
After the lens provided by the technical scheme of the embodiment is made into glasses, the strabismus diopter deviation and strabismus astigmatism of a wearer can be effectively reduced.
Example 3
In this embodiment, the prescription provides the following parameters: distance left lens of 6 diopters, refractive index 1.597. The vertical inclination angle of the lens is 8 degrees and the horizontal inclination angle is 6 degrees after the wearer wears the selected spectacle frame, and the distance from the intersection point of the sight line and the lens to the pupil is 25 mm when the wearer looks flat.
The evaluation model and lens design flow provided in example 1 were followed with the following specific steps:
1. firstly, according to the diopter and material refractive index provided by an optometry prescription, the front surface and the back surface are selected to be spherical surfaces and used as initial lenses, the front surface of each lens has the diopter of 1, the curvature radius of 597 mm, and the center thickness of each lens is 1.2 mm. Corresponding to a rear surface radius of curvature of 85.2 mm. The refractive power evaluation of the initial lens without tilt was performed by the spectacle-eye pupil model, and the variation of the strabismus diopter and strabismus astigmatism with the viewing angle of the human eye was obtained as shown in fig. 10. The strabismus diopter gradually deviates from the required-6 diopter with the increase of the visual angle of the human eye, and the strabismus diopter increases to-6.88 diopter at the visual angle of 35 degrees, the deviation value is 0.88 diopter, and the deviation percentage (D) isr-D0)/D00.147 strabismus astigmatism of 1.23 diopters, Cr/|D0|=0.205。
2. Aspheric surface design of the rear surface is performed. The rise of the aspherical surface is determined by formula (3). The central curvature C of the aspheric surface is 0.01177mm-1. The conic coefficient K of the optimized aspheric surface is-3.44, and the coefficient a of the aspheric surface high-order term4=1.2×10-9,a6=6.7×10-12。a8=8.9×10-14a10=9.2×10-18,a12=-5.4×10-22. The refractive power of the aspherical lens was evaluated by an evaluation model without tilting, and the change of the strabismus diopter and strabismus astigmatism with the visual angle of the human eye was obtained as shown in fig. 11. Strabismus diopter at 35 degrees of viewing angle is-6.03 diopter, deviation value is 0.03 diopter, and deviation percentage (D)r-D0)/D00.005 strabismus astigmatism 0.30 diopter, Cr/|D0The strabismus diopter deviation and strabismus astigmatism are small, 0.05.
3. The designed aspheric lens is re-evaluated through an evaluation model according to the vertical inclination angle of 8 degrees and the horizontal inclination angle of 6 degrees provided by the prescription, the upper part of the lens is inclined outwards by 8 degrees, and the left side of the lens is inclined inwards by 6 degrees (left lens). The refractive power evaluation results are shown in fig. 12. After the lens is tilted, the diopter at the central line of sight of the lens deviates from the prescription requirement of-6 diopters, which is-6.15 diopters. The squint diopters in the up-down and left-right directions change, and the diopters are-6.54 diopters at the upward 30-degree visual angle, are-5.77 diopters at the downward 30-degree visual angle, are-6.46 diopters at the nasal 30-degree visual angle, and are-5.87 diopters at the temporal 30-degree visual angle. The strabismus astigmatism in the up-down and left-right directions is obviously asymmetric, 1.0 diopter is formed at the upward 30-degree visual angle, 0.048 diopter is formed at the downward 30-degree visual angle, 0.91 diopter is formed at the nasal 30-degree visual angle, and 0.18 diopter is formed at the temporal 30-degree visual angle. The evaluation results show that although the designed aspheric lens meets the requirements of deviation of the strabismus diopter and strabismus astigmatism in the non-inclined state, after a wearer wears the glasses with the aspheric lens, the actual refractive power in the strabismus state is greatly changed, the maximum deviation of the strabismus diopter is 0.54 diopter, and the strabismus astigmatism reaches 1.0 diopter. Especially for the myopic lens wearer, the wide visual field is needed when the myopic lens wearer looks away, and the deviation of strabismus diopter and large strabismus astigmatism cause the wearer to have uncomfortable feelings such as unclear vision, dizziness and the like.
According to the evaluation results, the sagittal height data of the lens front surface is subjected to asymmetry compensation and central diopter compensation. The asymmetric compensation is realized by longitudinal and transverse cubic term values, and the rise compensation value of the cubic term is as follows:
Zc(x,y)=bx(x±xd)3+by(y+yd)3,
wherein the coefficient of transverse cubic term bxis-4.2X 10-6(ii) a Transverse movement xd7.6 mm, and the left mirror adopts a plus sign; coefficient of longitudinal cubic term byIs 6.9X 10-6Longitudinal movement ydIs 5.2 mm.
The center curvature of the front surface of the vernier lens was 0.01173mm-1To achieve diopter compensation of the central line of sight.
The refractive power evaluation in the lens inclination state by the evaluation model is shown in fig. 13, in which the sagitta data of the front surface of the aspherical lens obtained by design is added with the sagitta compensation value of the cubic term of the asymmetric compensation and the diopter compensation at the central sight line, to obtain sagitta data of the asymmetric curved lens. The diopter at the central vision of the lens meets the prescription requirement of-6 diopters. The asymmetry of strabismus diopter deviation in the up-down and left-right directions is obviously improved, wherein the diopter deviation is-6.21 diopters at the upward 30-degree visual angle, is-5.80 diopters at the downward 30-degree visual angle, is-6.21 diopters at the nasal side 30-degree visual angle and is-5.84 diopters at the temporal side 30-degree visual angle. The strabismus astigmatism in the up-down and left-right directions is obviously reduced, the upward 30-degree visual angle is 0.590 diopter, the downward 30-degree visual angle is 0.338 diopter, the nasal 30-degree visual angle is 0.693 diopter, and the temporal 30-degree visual angle is 0.375 diopter.
Evaluation results of the evaluation model showed that the wearer wearing the lens having the asymmetric curved surface structure according to the present embodiment showed that the maximum deviation of strabismus diopter was 0.23 diopter (at 27 degrees from the upward viewing angle) and the maximum strabismus astigmatism was 0.693, both of which were not more than 0.125| D, in the viewing range of 30 degrees from the viewing angle00.75 diopter. The comfort degree of the wearer in oblique vision is greatly improved.