CN105572901B

CN105572901B - Aspheric diffractive contact lens for correcting myopia and presbyopia

Info

Publication number: CN105572901B
Application number: CN201610102512.8A
Authority: CN
Inventors: 刘永基; 姜来; 王晓琳; 王肇圻
Original assignee: Nankai University
Current assignee: Nankai University
Priority date: 2016-02-25
Filing date: 2016-02-25
Publication date: 2020-06-23
Anticipated expiration: 2036-02-25
Also published as: CN105572901A

Abstract

An aspheric diffractive contact lens for correcting myopia and presbyopia and having a certain accommodation ability for human eyes. The diameter of the optical part of the contact lens is 6mm, the front surface of the contact lens is a convex aspheric surface and is axially symmetrical, and a diffraction ring for providing an addition diopter is arranged on the front surface of the contact lens. The posterior surface conforms to the cornea of a human eye and has a radius of curvature that is consistent with the anterior surface of the cornea. The contact lens can be worn to clearly image the middle distance to the long distance (450mm to infinite distance) and the reading distance nearby (240mm to 260mm) in a +/-4-degree visual field. In addition, the contact lens has another remarkable characteristic that the large depth of field performance and the vision are stable along with the change of pupils.

Description

Aspheric diffractive contact lens for correcting myopia and presbyopia

Technical Field

The invention belongs to the field of refraction and diffraction mixed ophthalmic lenses, and particularly relates to a contact lens with large depth of field, which can provide a continuous clear object range for human eyes, and meanwhile, the performance of the contact lens is kept stable when the size of a pupil is changed.

Background

In the natural state of the normal human eye, without accommodation, an infinitely distant object is imaged exactly on the retina. When observing a near object, the eye automatically generates an accommodation signal, the ciliary muscle contracts, and the radius of curvature of the lens surface decreases. However, with age, the accommodative ability of the muscles deteriorates and the accommodative ability of the lens gradually decreases, thereby forming presbyopia which can only be clearly imaged for a specific distance. With the increase of the population of the elderly in China, the presbyopia correction is concerned more and more, and meanwhile, a large market is brought.

The most traditional method of correcting presbyopia is frame eyewear. The general frame glasses have specific diopter, only objects at a specific distance (generally, reading distance) can be clearly seen, and other distances are not clear. In order to overcome the single focus deficiency of the common presbyopic glasses, the design of bifocal glasses and progressive lenses is proposed and applied to the market successively. At the same time, multifocal (mostly bifocal) contact lenses and ophthalmic intraocular lens designs are being proposed that aim to provide more imaging range to the human eye. The main drawback of this type of design (which can be partially overcome by the new trifocal design) is that the two points, far and near, are clearly visible, while the middle is not.

The human eye develops presbyopia after age 40, and the degree of presbyopia gradually increases with age. Meanwhile, China is a big myopia country, and after the myopia people step into the old, the eyesight of the people is troubled by myopia and the old. This part of the population has a feature that, despite presbyopia, there is a certain degree of accommodation. Therefore, the invention provides a contact lens capable of providing a continuous depth of field range for the part of the human eye with myopia and presbyopia. In addition, a significant difference between the human eye and other optical systems is that the stop (pupil) changes depending on the light intensity, and thus the performance of the contact lens should remain stable as the pupil size changes.

Disclosure of Invention

The invention aims to overcome the defects of the existing contact lenses, take the residual adjustment force of actual human eyes into consideration, provide the aspheric diffractive contact lens for correcting the human eyes with certain adjustment, which are myopic and presbyopic, and improve the optical performance of the eyes wearing the contact lenses.

The invention provides an aspheric diffraction type contact lens for correcting myopia and presbyopia and having a certain adjusting capacity for human eyes, which comprises an optical component and a lens component, wherein the optical component comprises a front surface and a rear surface, has a large depth of field performance and can correct the vision from the middle distance to the remote distance, namely 450 mm-infinite distance, of the human eyes with certain adjusting capacity for correcting myopia and presbyopia; the optical component is provided with the diffraction ring, so that the short-range distance of the short-range vision of the presbyopia person, namely the vision of 240 mm-260 mm, which is caused by the myopia with a certain adjusting power can be corrected. The front surface diffraction ring radii are respectively: 0.743mm, 1.057mm, 1.296mm, 1.494mm, 1.664mm, 1.815mm, 1.954mm, 2.087mm, 2.224mm, 2.409mm, 2.578mm, 2.693mm, 2.751mm, 2.794mm, 2.829mm, 2.858mm, 2.883mm, 2.906mm, 2.927mm, 2.945mm, 2.963mm, 2.979mm, 2.994 mm.

The optical component of the present invention has a large depth of field capability provided by the front surface of the optical component, the front surface being an even aspheric surface, and the front surface of the contact lens being described by a surface profile

Wherein, a₁～a₅The even-order aspheric coefficients from 4 th order to 10 th order are sequentially obtained, c is the curvature at the vertex of the aspheric surface, r is the distance from any point on the aspheric surface to the optical axis, and k is the conic coefficient. The aspheric coefficients of the anterior surface are: a is₁＝-3.840E-003、a₂＝-1.560E-004、a₃＝-8.060E-005、a₄＝-5.170E-005、a₅＝-8.150E-006。

The optical component back surface is attached to the cornea of the human eye with a radius of curvature that is consistent with the cornea front surface.

The basic parameters of the front surface of the aspheric diffractive contact lens are as follows: the radius of curvature of the anterior surface is 8.11mm, the center thickness of the contact lens is between 0.05mm and 0.25mm, and the conic coefficient is-17.772; the diameter of the optical part is 6 mm.

The vision of the contact lens is kept stable along with the change of pupils, and the vision of the contact lens wearing the contact lens is better than 0.8 for the vision of 450mm to infinite distance and 240mm to 260mm under pupils with different diameters.

In order to better correct the visual defects of presbyopia and simultaneously consider that human eyes have a certain visual field range, the vision of the invention is kept stable in a visual field of +/-4 degrees.

Advantages and advantageous effects of the invention

The invention uses Zemax optical design software to optimize the surface type of the contact lens and obtain the aspheric diffraction type contact lens. The invention has the following functions and advantages:

first, the aspheric diffractive contact lens is aspheric surface treated on the surface of the contact lens, providing a large depth of field performance and achieving continuous intermediate to remote vision.

Second, the addition of a diffractive ring on the aspheric surface provides add power to achieve near reading vision.

Third, the contact lenses can correct presbyopic eyes with myopia.

Fourth, vision at 450mm to infinite distance and 240mm to 260mm is better than 0.8 for eyes wearing contact lenses with pupils of different diameters.

Fifthly, the diameter of the optical part of the contact lens is 6mm, which basically meets the requirement of the actual human eye.

Sixth, the macular fovea of the retina accumulates a large number of cone cells, the density of which decreases sharply with distance from the fovea. At a position 1mm from the fovea, the density of the cones drops by an order of magnitude, this position corresponding exactly to a field of view of ± 4 °. In order to better correct the visual defects of presbyopia, the optical performance of the contact lens eye worn on a +/-4-degree visual field is verified, and the modulation transfer function curve on the +/-4-degree visual field is found to have small decline on different object distances of different pupils, and most of the modulation transfer function curve is higher than 0.4 at the spatial frequency of 100 c/mm.

Drawings

Fig. 1 is a side view of an aspheric diffractive contact lens.

Fig. 2 is an MTF curve at different object distances at a 0 ° field of view 2.8mm pupil diameter.

Fig. 3 is an MTF curve at different object distances at a pupil diameter of 3mm at a field of 0 °.

Fig. 4 is an MTF curve at different object distances at a 4.5mm pupil diameter at a 0 ° field of view.

Fig. 5 is an MTF curve at different object distances at a 0 ° field of view 5mm pupil diameter.

Fig. 6 is an MTF curve at different object distances at a 6mm pupil diameter at a 0 ° field of view.

Fig. 7 is an MTF curve at different object distances at a4 ° field of view 2.8mm pupil diameter.

Fig. 8 is an MTF curve at different object distances at a4 ° field of view 3mm pupil diameter.

Fig. 9 is an MTF curve at different object distances at a4 ° field of view 4.5mm pupil diameter.

Fig. 10 is an MTF curve at different object distances at a4 ° field of view 5mm pupil diameter.

Fig. 11 is an MTF curve at different object distances at a4 ° field of view, 6mm pupil diameter.

FIG. 12 is a graph of the vision curve at a pupil diameter of 2.8mm at 0 degrees from 450mm to infinity, where D is diopter, which is the unit of lens power, e.g., the focal length of a lens is 1m, and the refractive power of the lens is 1D diopter. Different object distances can therefore be expressed in diopters, i.e. 1/object distance (m).

Figure 13 is a plot of vision at 450mm to infinity object distances and 235mm to 270mm object distances at a 0 field of view of 3mm pupil diameter.

Figure 14 is a plot of vision at 450mm to infinity object distance and 235mm to 270mm object distance at a 0 field of view 4.5mm pupil diameter.

Figure 15 is a plot of vision at 450mm to infinity object distances and 235mm to 270mm object distances at a 0 field of view 5mm pupil diameter.

Figure 16 is a plot of vision at 450mm to infinity object distances and 235mm to 270mm object distances at a 0 field of view of 6mm pupil diameter.

Detailed Description

The following will further describe the details of the aspheric diffractive contact lens for correcting myopia and presbyopia provided by the present invention with reference to the accompanying drawings and embodiments.

Example 1

As shown in fig. 1, a side view of an aspheric diffractive contact lens. An aspherical diffractive contact lens comprises an optical anterior surface 1 and a posterior surface 2. The whole contact lens is axially symmetrical, and the front surface of the optical part is a convex aspheric surface and is attached with a diffraction ring.

Through optimization, an aspheric diffraction type contact lens which realizes large depth of field (450 mm-infinite distance) and has additional focal power (250mm) is finally designed, the front surface of the contact lens is an even aspheric surface, the selected material is a hard high oxygen permeable contact lens material, the refractive index of the hard high oxygen permeable contact lens material is 1.432, and the Abbe number is 55.15.

The basic structural parameters are shown in table 1:

TABLE 1 basic parameters of contact lenses

The profile of the aspheric contact lens surface can be described as:

wherein, a₁～a₅The even-order aspheric coefficients from 4 th order to 10 th order are sequentially obtained, c is the curvature at the vertex of the aspheric surface, r is the distance from any point on the aspheric surface to the optical axis, and k is the conic coefficient.

Front surface aspheric coefficient a₁～a₅As shown in table 2:

TABLE 2 front surface aspheric coefficients of contact lenses

Radius of the diffraction ring of the front surface, as shown in table 3:

TABLE 3 anterior surface phase coefficient of contact lenses

The side (and top) views are as in fig. 1. And in the eye model, the Modulation Transfer Function (MTF) and Visual Acuity (VA) were analyzed for different positions from 450mm to infinite distance and over a range from 240mm to 260 mm. The properties of this contact lens were obtained as follows:

1) the MTF curves are well balanced for different pupil diameters and different object distance positions for the contact lens at a 0 ° field of view. As in FIGS. 3-7, the MTF curves dropped slowly, all above 0.2 at a spatial period frequency of 100 c/mm.

2) The acutance of the human eye obtained by the contact lens under the 0 degree visual field under different object distances is as shown in fig. 13 to 16, the vision at the positions of 450mm to infinite distance and 240mm to 260mm under different pupil diameters is between 0.6 and 1.0 except for the vision at the individual positions, and the vision at most positions is better than 1.0, so that good correction effect is obtained.

3) The present invention verifies the optical performance of contact lens eyes wearing a ± 4 ° field of view, as shown in fig. 8 to 12, and finds that the drop of the ± 4 ° modulation transfer function curve is small at different object distances of different pupils, and most of the drop is higher than 0.4 at the spatial frequency of 100 c/mm.

In conclusion, the contact lens eye obtains good optical performance in the whole range from 450mm to infinite distance (from middle range to long range) and 240mm to 260mm (from photopic distance), and achieves the effect of large depth of field.

Claims

1. An aspheric diffractive contact lens for correcting myopia and presbyopia and having a certain eye accommodation capacity, characterized in that the whole contact lens is axially symmetrical, the front surface of an optical component of the contact lens is a convex aspheric surface and is attached with a diffractive ring, the diameter of the optical component is 6mm, the optical component comprises a front surface and a rear surface, the front surface of the optical component is an aspheric surface, and the aspheric surface can correct the vision from the middle distance to the remote distance of the eye of a person with myopia and presbyopia with a certain accommodation capacity, namely 450mm to infinite distance; the back surface of the optical component is attached to the cornea of the human eye, and the curvature radius is consistent with the surface of the cornea;

the basic parameters of the front surface of the optical component are: the radius of curvature of the anterior surface is 8.11mm, the center thickness of the contact lens is between 0.05mm and 0.25mm, and the conic coefficient is-17.772;

the diffraction ring can correct short-range distance of eyes of a person with myopia and presbyopia with certain adjusting power, namely the eyesight of 240 mm-260 mm.

2. The contact lens of claim 1 wherein said anterior surface diffractive ring radii are respectively: 0.743mm, 1.057mm, 1.296mm, 1.494mm, 1.664mm, 1.815mm, 1.954mm, 2.087mm, 2.224mm, 2.409mm, 2.578mm, 2.693mm, 2.751mm, 2.794mm, 2.829mm, 2.858mm, 2.883mm, 2.906mm, 2.927mm, 2.945mm, 2.963mm, 2.979mm, 2.994 mm.

3. The contact lens of claim 1 wherein said optic has a large depth of field capability provided by an anterior surface of the optic, the anterior surface being configured as an even aspheric surface, the anterior surface of the contact lens being characterized by a profile described as an even aspheric surface

Wherein, a 1-a 5 are even-order aspheric coefficients from 4 th order to 10 th order in sequence, c is the curvature at the vertex of the aspheric surface, r is the distance from any point on the aspheric surface to the optical axis, and k is a conic coefficient.

4. The contact lens of claim 3 wherein said anterior surface has aspheric coefficients of: a1 ═ 3.840E-003, a2 ═ 1.560E-004, a3 ═ 8.060E-005, a4 ═ 5.170E-005, and a5 ═ 8.150E-006.