HK40056181B - Contact lens with improved visual performance and minimized halo utilizing pupil apodization - Google Patents

Description

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

The present application is a divisional application of patent application filed on 8.18 2017, with application number 201710713351.0, entitled "contact lens with improved visual performance and minimized halation with pupil apodization".

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 combines the concept of smooth pupil transitions with higher edge absorption to provide improved visual performance with reduced pupil edge wavefront aberration, reduced halation, and reduced light scattering.

Background

Myopia or nearsightedness is an optical or refractive defect of the eye in which light rays from an image are focused into a spot 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 presbyopia is an optical or refractive defect of the eye in which light rays from an image are focused into a point after they reach or behind the retina. In general, hyperopia occurs because the eyeball or spheroid is too short or the cornea is too flat. Positive number or positive power spherical lenses may be used to correct hyperopia. Astigmatism is an optical or refractive defect in which an individual's vision is blurred because the eye is unable to focus a point target into a focused image on the retina. Astigmatism is caused by an abnormal curvature of the cornea. The 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, so that the image is stretched rather than focused into a spot. Cylindrical lenses may be used instead of aspherical lenses to eliminate astigmatism.

Contact lenses may 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 placed on an eye. Contact lenses are considered medical devices and may be worn to correct vision and/or for cosmetic or other therapeutic reasons. Contact lenses have been used commercially to improve vision since the 50 s of the 20 th century. Early contact lenses were made or constructed of hard materials, which were relatively expensive and fragile. Furthermore, these early contact lenses were made of materials that did not allow sufficient oxygen to be transported through the contact lens to the conjunctiva and cornea, potentially causing many adverse clinical effects. Although these contact lenses are still used, they are not suitable for all patients due to poor initial comfort. Subsequent developments in this field have resulted in soft contact lenses based on hydrogels, which are extremely popular and widely used today. In particular, silicone hydrogel contact lenses available today combine the benefits of silicone with extremely high oxygen permeability with the proven comfort and clinical performance of hydrogels. In essence, these silicone hydrogel-based contact lenses have a 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 halation effects and/or light scattering during high or intense exposure, such as during night driving. This phenomenon is due to light diffraction at the edges 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 halation, and reduced light scattering.

Disclosure of Invention

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

According to one aspect, the present invention relates to soft contact lenses having improved visual properties. The 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.

Halation and light scattering are mainly caused by the 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 halation effects, the transmission curve of soft contact lenses is changed relative to current soft contact lens designs. In accordance with the present invention, a smooth pupil apodization function is applied to the lens design to eliminate or substantially minimize light diffraction at the edges of the pupil, while applying higher absorption at the lens edges 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, the optical rays refracted at the pupil edge or at the soft contact lens edge may not precisely converge at the imaging point and thus blurred images may be observed. Such blurred images caused by wavefront aberrations at the pupil edge or soft contact lens edge can reduce 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 aberration plays a significantly reduced role in the overall retinal image. Basically, by applying a smooth pupil apodization function, better vision correction performance of the lens can be achieved.

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

The soft contact lenses of the invention are easy to manufacture using standard manufacturing techniques and thus 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.

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

FIG. 1B is a corresponding light transmission curve 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 in accordance with the present invention.

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

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

Fig. 5 is a graphical representation of an apodization with respect to halo intensity according to the present invention.

Detailed Description

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

Currently available contact lenses remain a cost effective device for vision correction. Thin plastic lenses are fitted 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 lens accommodation). Contact lenses are available in a variety of forms and are made of a variety of materials to provide different functionalities. Daily wear soft contact lenses are typically made of soft polymeric materials that are combined with water for oxygen permeability. The daily wear type soft contact lens can be daily throwing type or long wear type. Daily disposable contact lenses are typically worn for a day and then discarded, while extended wear contact lenses are typically worn for a period of up to thirty days. Colored soft contact lenses use different materials to provide different functionalities. For example, a visual tone contact lens uses a light tone to help the wearer locate a dropped contact lens, an enhanced tone contact lens has a translucent tone to enhance the natural eye color of a person, a colored tone contact lens includes a darker opaque tone to change the eye color of a person, and a filtered tone contact lens is used to enhance certain colors while weakening others. Rigid gas permeable hard contact lenses are made of silicone-containing polymers, but are more rigid than soft contact lenses and thus retain their shape and are more durable. Bifocal contact lenses are particularly designed for presbyopic patients and are available in soft and rigid varieties. Toric contact lenses are particularly designed for astigmatic patients and are also available in soft and rigid varieties. A combination lens combining the above different aspects is also available, such as a hybrid contact lens.

The 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 the 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 an amplitude modulation component a (x, y) and a phase modulation component W (x, y), where exp [ jW (x, y) ] is an imaginary component of the phase term. In the current design of soft contact lenses, the optical phase change curve W (x, y) is modified and improved to enhance vision; however, as can be readily seen from equation (1), the pupil function P (x, y) of the optical system is also dependent on or a function of its amplitude modulation function a (x, y). According to the invention, the optical correction properties of soft contact lenses can be further improved by specifically designing the amplitude modulation function a (x, y) in addition to the improvement made by the manipulation W (x, y). These additional improvements relate to pupil edge wavefront aberrations and halation, particularly in terms of both reduction.

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*(r ² /r ₀ ² ))， (2)

where r= v (x ² +y ² )，r ₀ Is the optical zone radius and α is the constant that determines the type of pupil apodizationNumber, as it is 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 one exemplary embodiment, an apodized soft contact lens may be designed using equations (1) and (2), and the resulting visual acuity may be modeled with an eye model. As shown in fig. 1A, different magnitudes α 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 of pupil functions 100',102' and 104' for each α in fig. 1A. As can be seen from the three panels, the effect on pupil edge wavefront aberration is reduced and there is less halo, but less transmitted light, as apodization becomes stronger. This is a compromise; that is, the transmitted light has an effect on the reduced halo and reduced edge wavefront aberration. As shown in the third panel 104 of fig. 1A, the edge of the lens transmits less light.

As set forth above, apodized soft contact lenses can be designed using formulas (1) and (2), and the resulting visual acuity can be simulated with 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 profile is obtained by clinical measurements of the eyes of patients, whose ages vary between 20 and 60 years and have refractive errors (predetermined populations) in the range between +8d and-12D. Modeling is then applied to summarize all measured ocular spherical aberration information and mathematical functions are used to describe the mean and standard deviation of ocular spherical aberrations for patients of different ages and with different refractive errors. Using eye models, inMonte Carlo simulation was further performed across multiple eyes of the predetermined population. A common spherical lens with different apodization magnitudes indicated by α is individually fitted with multiple eyes generated by an eye model and Visual Acuity (VA) is calculated separately. The same spherical lens, which 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 an eye with an apodized soft contact lens and an eye with a soft contact lens without apodization is calculated and defined as 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, r ₀ Is fixed or held at 4 and r varies between 0 and 4. As shown, different amounts of apodization (varying α) exhibited different levels of visual acuity improvement. As apodization is stronger, i.e. a is larger, a higher level of visual acuity improvement is observed. As one example, where α is equal to 0.8, the average overall visual acuity improvement is above line 0.5. This is reasonable because stronger apodization results in smaller "effective" pupil sizes. In terms of visual acuity, an α equal to 3 provides the greatest improvement in visual acuity as shown in fig. 2, but one must remember that this is a compromise in light transmission.

The standard deviation of vision improvement is actually due to ocular spherical aberration variations within the population. In general, 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 of night visual acuity is effective in minimizing night myopia. On average, positive ocular spherical aberration exists in the human eye. This normothermic spherical aberration plays a more important role during the night due to the large pupil size at low light (dilation). This increased amount of ocular spherical aberration during night can contribute to night myopia effects. By applying a smooth pupil apodization according to the invention, the edge light intensity can be reduced, thereby reducing night myopia. In other words, night vision reduction is a direct result of reducing marginal wavefront aberrations.

Not only can visual acuity be improved by the present invention, but halation (diffraction at the edge of the pupil) and light scattering (multiple reflections at the edge of the lens) can be significantly reduced with smooth transitions in pupil transmission. The reduction of halation and light scattering can be demonstrated by optical ray tracing. As shown in fig. 3, with an apodized pupil function 304, a much weaker halo can be observed in the final image point spread function 306. 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 scattering is due to light reflection 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 halation arises from the high illumination at night. During night driving, intense beam illumination incident on the vehicle causes halation 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 apodization amounts. 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 decreasing halo, the light intensity entering the pupil will continue to decrease and generally should be less than 10 for comfortable vision α. With 10, the total transmission of light is 11.1 percent. According to the invention, α preferably varies between 0.1 and 10.

The apodization of soft contact lenses according to equation (1) and equation (2) can be made with a thin coating of neutral density filter having a transmission of varying transmissivity over the optical area of the lens. As is known in the art, neutral density filters uniformly block light across the spectrum. Such neutral density filter coatings may be applied or implemented using any suitable means including coating and printing techniques. Further, any number of suitable coatings may be utilized. The coating may be applied to the lens itself or in the lens itself.

While what has been shown and described is believed to be the most practical and preferred embodiment, it is apparent that modifications to the specific designs and methods described and illustrated will provide a reference to those skilled in the art and that such modifications may be used 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 properties, the soft contact lens comprising:

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

a peripheral region surrounding the optical region and extending to a lens edge, wherein the contact lens is configured 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, a neutral density filter is applied to the soft contact lens to achieve the smooth pupil apodization function expressed mathematically as a (r) =exp (- α (r) ² /r ₀ ² ) Where alpha ranges between 0.1 and 10, r when the calculation of A (r) is performed ₀ Is set equal to the radius of the optical zone, and r ranges between 0 and r ₀ Wherein r is ₀ For the optical zone radius, α is a constant that determines the type of pupil apodization and r is a radial measurement from the lens center at cylindrical coordinates.

2. The soft contact lens of claim 1 wherein r ₀ Is set to 4mm.

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

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