HK40056181A - Contact lens with improved visual performance and minimized halo utilizing pupil apodization - Google Patents

Description

Contact lenses with improved visual performance and minimized halo using pupil apodization

The present application is a divisional application of the patent application entitled "contact lens with improved visual properties and minimized halo with pupil apodization" filed on 8/18/2017 under application number 201710713351.0.

Technical Field

The present invention relates to ophthalmic lenses, and more particularly to soft contact lenses including designs for modulating the lens amplitude transmission curve that combine the concepts of smooth pupil transition with higher edge absorption to provide improved visual performance with reduced pupil edge wavefront aberration, reduced halo, and reduced light scattering.

Background

Myopia or nearsightedness is an optical or refractive defect of the eye in which the rays from the image are focused to a point before they reach the retina. Generally, myopia occurs because the eyeball or spheroid is too long or the cornea is too steep. Negative or negative power spherical lenses may be used to correct myopia. Hyperopia or hyperopia is an optical or refractive defect of the eye in which rays from an image are focused into a spot after they reach or behind the retina. Generally, hyperopia occurs because the eyeball or spheroid is too short or the cornea is too flat. A positive or positive power spherical lens may be used to correct hyperopia. Astigmatism is an optical or refractive defect in which an individual's vision is blurred by the inability of the eye to focus a point object into a focused image on the retina. Astigmatism is caused by an abnormal curvature of the cornea. An intact cornea is spherical, whereas in individuals with astigmatism, the cornea is aspherical. In other words, the cornea is actually more curved or steeper in one direction than in the other, causing the image to be stretched rather than focused into a point. Cylindrical lenses may be used and aspherical lenses to eliminate astigmatism.

Contact lenses can be used to correct myopia, hyperopia, astigmatism, and other visual acuity deficiencies. Contact lenses may also be used to enhance the natural appearance of the wearer's eyes. A contact lens or contact lens is simply a lens that is placed on the eye. Contact lenses are considered medical devices and may be worn to correct vision and/or for cosmetic or other therapeutic reasons. Since the 50 s of the 20 th century, contact lenses have been used commercially to improve vision. Early contact lenses were made or constructed of hard materials, were relatively expensive and fragile. In addition, these early contact lenses were made of materials that did not allow sufficient oxygen transmission through the contact lens to the conjunctiva and cornea, which potentially could cause a number of adverse clinical effects. Although these contact lenses are still used, they are not suitable for all patients due to their poor initial comfort. Subsequent developments in this area have resulted in soft contact lenses based on hydrogels, which are extremely popular and widely utilized today. In particular, silicone hydrogel contact lenses available today combine the benefits of silicones with very high oxygen permeability with the proven comfort and clinical performance of hydrogels. In essence, these silicone hydrogel based contact lenses have higher oxygen permeability and are generally more comfortable to wear than contact lenses made from earlier hard materials.

Soft contact lenses have been widely used as effective vision correction devices by providing different types of wavefront aberrations, including defocus and astigmatism, all with a high degree of comfort and ease of use for the patient. However, some patients experience halo effects and/or light scattering during high or intense exposure, such as during night driving. This phenomenon is due to light diffraction at the edge of the patient's pupil and multiple reflections within the soft contact lens itself. Accordingly, there is a need for a soft contact lens that provides a healthy and comfortable means for the patient to ensure optical vision correction with reduced pupil edge wavefront aberrations, reduced halos, and reduced light scattering.

Disclosure of Invention

The contact lens with improved visual performance and minimized halo utilizing pupil apodization according to the present invention overcomes the disadvantages associated with the prior art briefly described above.

According to one aspect, the present invention relates to soft contact lenses having improved visual performance. A soft contact lens includes an optical zone, a peripheral zone surrounding the optical zone, and a system pupil function having an amplitude modulation component and a phase modulation component applied across at least a portion of the optical zone and the peripheral zone, the amplitude modulation component including a smooth transition function.

Halo and light scattering are mainly caused by two components of soft contact lenses. The first component comes from light diffraction at the edge of the pupil and the second component comes from multiple internal reflections/light scattering within the material forming the soft contact lens. To overcome or minimize light scattering or halo effects, the transmission curve of soft contact lenses is changed relative to current soft contact lens designs. According to the present invention, a smooth pupil apodization function is applied to the lens design to eliminate or substantially minimize light diffraction at the edge of the pupil, while applying a higher absorption at the lens edge will significantly reduce and preferably eliminate multiple light reflections with soft contact lenses.

Contact lenses, and more particularly, soft contact lenses, are designed to correct refractive errors of spherical and/or cylindrical power. However, due to higher order aberrations, optical rays refracted at the pupil edge or the soft contact lens edge may not accurately converge to an imaging point and thus a blurred image may be observed. Such blurred images caused by wavefront aberrations at the pupil edge or soft contact lens edge can degrade the overall lens vision correction performance. By applying a smooth pupil apodization function, the pupil edge or soft contact lens edge has a stronger absorption and the light rays passing through the pupil edge or soft contact lens edge will have a significantly reduced intensity and thus the edge wavefront aberrations play a significantly reduced role in the overall retinal image. Basically, by applying a smooth pupil apodization function, better lens vision correction performance can be obtained.

Mathematically, an optical system can be generally described by its phase modulation function and its amplitude transfer function. Typically; however, in the current state of the art for soft contact lenses, only phase modulation is used to incorporate optical properties into the soft contact lens. In the present invention, soft contact lenses are designed to modulate the lens amplitude transmission curve, which combines the concepts of smooth pupil transition and higher edge absorption together with phase modulation to ensure optimal vision correction while substantially minimizing or eliminating lens halo, reducing pupil edge wavefront aberrations and light scattering.

The soft contact lenses of the invention are easy to manufacture using standard manufacturing techniques and therefore provide more comfortable, healthy and clear vision at a reasonable cost.

Drawings

The foregoing and other features and advantages of the invention will be apparent from the following more particular description of preferred embodiments of the invention, as illustrated in the accompanying drawings.

Figure 1A is a representation of different pupil apodization designs according to the present invention.

FIG. 1B is a graph of the corresponding light transmission curves for the different apodization designs of FIG. 1A.

FIG. 2 is a graphical representation of the mean and standard deviation of visual acuity improvement versus vergence as calculated according to the present invention.

Figures 3A-3D illustrate apodized and non-apodized pupil functions and point spread functions according to the present invention.

Fig. 4A and 4B illustrate light entering the peripheral portion of a soft contact lens without apodization and light entering the peripheral portion of a soft contact lens with apodization according to the present invention.

Fig. 5 is a graphical representation of relative halo intensity versus apodization according to the present invention.

Detailed Description

A contact lens or contact lens is simply a lens that is placed on the eye. Contact lenses are considered medical devices and may be worn to correct vision and/or for cosmetic or other therapeutic reasons. Since the 50 s of the 20 th century, contact lenses have been used commercially to improve vision. Early contact lenses were made or manufactured from hard materials, were relatively expensive and fragile. In addition, these early contact lenses were made of materials that did not allow sufficient oxygen transmission through the contact lens to the conjunctiva and cornea, which potentially could cause a number of adverse clinical effects. Although these contact lenses are still used, they are not suitable for all patients due to their poor initial comfort. Subsequent developments in this area have resulted in soft contact lenses based on hydrogels, which are extremely popular and widely utilized today. In particular, silicone hydrogel contact lenses available today combine the benefits of silicones with very high oxygen permeability with the proven comfort and clinical performance of hydrogels. In essence, these silicone hydrogel based contact lenses have higher oxygen permeability and are generally more comfortable to wear than contact lenses made from earlier hard materials.

Currently available contact lenses remain cost effective devices for vision correction. Thin plastic lenses fit over the cornea of the eye to correct vision defects including myopia or nearsightedness, hyperopia or farsightedness, astigmatism (i.e., asphericity in the cornea), and presbyopia (i.e., loss of accommodation to the lens). Contact lenses are available in a variety of forms and are made from a variety of materials to provide different functionalities. Soft contact lenses of the daily wear type are typically made of soft polymeric materials, which are combined with water for oxygen permeability. Soft daily contact lenses can be daily disposable or extended wear. Daily disposable contact lenses are typically worn for one day and then discarded, while extended wear contact lenses are typically worn for periods of up to thirty days. Colored soft contact lenses use different materials to provide different functionalities. For example, visible-tone contact lenses use light tones to help the wearer locate a dropped contact lens, enhanced-tone contact lenses have translucent tones for enhancing a person's natural eye color, colored-tone contact lenses include darker opaque tones for changing a person's eye color, and filter-tone contact lenses for enhancing certain colors while attenuating other colors. Rigid, gas permeable, hard contact lenses are made from silicone-containing polymers, but are more rigid than soft contact lenses, and therefore retain their shape and are more durable. Bifocal contact lenses are designed specifically for hyperopic patients and are available in both soft and rigid varieties. Toric contact lenses are designed specifically for astigmatic patients and are also available in both soft and rigid varieties. Combination lenses combining the above different aspects are also available, for example hybrid contact lenses.

An optical system can be fully described by its optical transfer functions (modulation transfer function and phase transfer function). The optical transfer function may be determined by an autocorrelation of the system pupil function P (x, y), which is given by:

P(x,y)＝A(x,y)exp[jW(x,y)]。 (1)

the system pupil function P (x, y) includes both amplitude modulation components a (x, y) and phase modulation components W (x, y), where exp [ jW (x, y) ] is the imaginary component of the phase term. In the current design of soft contact lenses, the optical phase variation curve W (x, y) is modified and improved to enhance vision; however, as can be readily seen from equation (1), the optical system pupil function P (x, y) also depends on or is a function of its amplitude modulation function a (x, y). In accordance with the present invention, by specifically designing the amplitude modulation function a (x, y), in addition to the improvement made by manipulating W (x, y), the soft contact lens optical correction properties can be further improved. These additional improvements relate to pupil edge wavefront aberrations and halos, particularly in reducing both.

In general, a smooth transition function may be applied to the amplitude modulation function a (x, y), which in this exemplary embodiment is given by:

A(r)＝exp(-α*(r²/r₀ ²))， (2)

wherein r ═ v (x)²+y²)，r₀Is the optic zone radius and alpha is a constant that determines the type of pupil apodization as explained in more detail below. In the present invention, the amplitude modulation function is any value other than 1. It is important to note that equation (2) is given in cylindrical coordinates rather than in cartesian coordinates, while equation (1) is given in cartesian coordinates. It is also important to note that transfer functions other than equation (2) may be used to determine the optical system pupil function P (x, y).

According to an exemplary embodiment, an apodized soft contact lens can be designed using equations (1) and (2), and the resulting visual acuity can be simulated using an eye model. As shown in fig. 1A, different magnitudes a will give various types of pupil apodization. In the first panel 100, α is equal to 0, which is the current state of the art for soft contact lenses, in the second panel 102, α is about 0.5, and in the third panel 104, α is about 1. Fig. 1B also indicates the corresponding transmission curves for the pupil functions 100 ', 102 ', and 104 ' for each a in fig. 1A. As can be seen from the three panels, the effect on the pupil edge wavefront aberration is reduced and there is less halo, but less light transmitted, as the apodization becomes stronger. This is a compromise; i.e. the transmitted light has an influence on the reduced halo and the reduced edge wave front aberration. As shown in the third panel 104 of fig. 1A, the edge of the lens transmits less light.

As set forth above, an apodized soft contact lens can be designed using equations (1) and (2), and the resulting visual acuity can be simulated using an eye model. The amount of ocular spherical aberration (SPHA), an indicator of visual performance, can be obtained by using an eye model. In the present invention, an eye model is developed that summarizes the average human eye spherical aberration across a predetermined population and its distribution or standard deviation. More specifically, the ocular spherical aberration distribution is obtained by clinical measurements on the eyes of patients whose ages vary between 20 and 60 years and have refractive errors (predetermined population) ranging between +8D and-12D. Modeling is then applied to summarize all measured ocular spherical aberration information and to describe the mean and standard deviation of ocular spherical aberration for patients of different ages and with different refractive errors using mathematical functions. Further monte carlo simulations were performed on multiple eyes across a predetermined population using the eye models. A normal spherical lens with different apodization values indicated by a is individually fitted with a number of eyes generated by the eye model and the Visual Acuity (VA) is calculated separately. The same spherical lens that is not apodized is also fitted with the same set or group of patient eyes and visual acuity is also calculated separately. For each individual eye, the difference in visual acuity between a soft contact lens with an apodization and an eye with a soft contact lens without an apodization is calculated and defined as the visual acuity improvement. FIG. 2 is a graphical representation of mean and standard deviation versus vergence for visual acuity improvement as calculated. In making this calculation, α varies from 0.3 to 3.0 as shown in the legend, r₀Is fixed or held at 4 and r varies between 0 and 4. As shown, different amounts of apodization (varying alpha) exhibited different levels of visual acuity improvement. As apodization is stronger, i.e. alpha is greater, a higher level of visual acuity improvement is observed. As an example, where a is equal to 0.8,the average total visual acuity improvement was above line 0.5. This is reasonable because stronger apodization results in a smaller "effective" pupil size. In terms of visual acuity, an alpha equal to 3 provides the greatest improvement in visual acuity as shown in fig. 2, but it must be remembered that this is a compromise in light transmission.

The standard deviation of vision improvement is actually due to ocular spherical aberration variation within the population. Generally, patients with higher positive ocular spherical aberration will benefit more than patients experiencing zero or negative ocular spherical aberration. The interaction between ocular spherical aberration and apodization has been studied and is known in the art. It is very important that the improvement in night vision acuity be effective in minimizing night myopia in humans. On average, positive ocular spherical aberration exists in the human eye. This positive ocular spherical aberration plays a more important role at night due to the large pupil size at low light (dilation). This increased amount of ocular spherical aberration at night may contribute to the night's near vision effect. By applying smooth pupil apodization according to the present invention, the peripheral light intensity can be reduced, thereby reducing night myopia. In other words, the reduction of night myopia is a direct result of the reduction of the peripheral wavefront aberrations.

Not only is visual acuity improved by the present invention, but halo (diffraction at the pupil edge) and light scattering (multiple reflections at the lens edge) can be significantly reduced with a smooth transition in pupil transmission. The reduction of halo and light scattering can be demonstrated with optical ray tracing. With an apodized pupil function 304, a much weaker halo can be observed in the final image point spread function 306, as shown in fig. 3. More specifically, as shown, without the apodized pupil function 300, the point spread function 302 shows a large halo. As mentioned above, a significant portion of the light scatter is due to light reflections at the lens or pupil edge. By applying apodization, the lens edge will have more light absorption, thereby reducing light scattering. Fig. 4A and 4B, which are described in detail below, illustrate this effect.

A significant problem with halos arises from high illumination light at night. During night driving, intense beam illumination incident on the vehicle results in the formation of a halo in the driver's peripheral vision. Fig. 4A shows light 400 entering a peripheral portion of a soft contact lens 402 without apodization and fig. 4B shows light 404 entering a peripheral portion of a soft contact lens 406 with apodization. As shown, apodization reduces the intensity of the peripheral incident light 404 as indicated by the dashed line 408. Assuming that the optical beam enters from the pupil edge, fig. 5 indicates halo intensities with different amounts of apodization. When α is equal to 0.8, the halo intensity is less than half (0.45) of the halo intensity without pupil apodization. With a reduced halo, the light intensity entering the pupil will continue to decrease and should generally be less than 10 for comfortable vision a. With 10, the total transmission of light is 11.1 percent. According to the invention, a preferably varies between 0.1 and 10.

Apodization of soft contact lenses according to equations (1) and (2) can be made with a thin coating of a neutral density filter having a transmission that varies in transmittance across the optical area of the lens. As is known in the art, a neutral density filter blocks light uniformly across the spectrum. Such neutral density filter coatings may be applied or achieved using any suitable means including coating and printing techniques. Further, any number of suitable coatings may be utilized. The coating may be applied onto or into the lens itself.

While the embodiments shown and described are believed to be the most practical and preferred embodiments, it is apparent that alterations to the specific designs and methods described and illustrated will provide a reference to those skilled in the art and that such variations may be employed without departing from the spirit and scope of the invention. The invention is not limited to the specific constructions described and shown, but should be constructed to conform to all modifications that may fall within the scope of the appended claims.

Claims (6)

1. A soft contact lens having improved visual performance, said soft contact lens comprising:

an optical zone surrounding a lens center and having a radius; and

a peripheral area surrounding the optical area and extending to the lens edge, wherein use is made ofConfiguring the contact lens with a smooth pupil apodization function centered at the lens center and extending to the lens edge to modulate an amplitude transmission curve of the soft contact lens such that the transmittance of the lens decreases continuously from the lens center to the lens edge, applying a neutral density filter to the soft contact lens to achieve the smooth pupil apodization function, expressing the smooth pupil apodization function mathematically as A (r) = exp (-a (r) =²/r₀ ²) Where alpha ranges between 0.1 and 10 when the calculation of A (r) is performed, r₀Is set equal to the radius of the optical area, and r ranges between 0 and r₀In the meantime.

2. A soft contact lens according to claim 1 wherein a ranges between 0.3 and 3.0 and r₀Set to 4 mm.

3. The soft contact lens of claim 1, wherein the neutral density filter reduces halos introduced by multiple reflections of optical rays within the soft contact lens compared to a soft contact lens without the neutral density filter.

4. A soft contact lens according to claim 3 wherein said neutral density filter is embedded within said contact lens.

5. A soft contact lens according to claim 3 wherein the neutral density filter is a coating applied to the surface of the contact lens.

6. A soft contact lens according to claim 3 wherein the neutral density filter is printed on the contact lens.