Patent Description:
In addition to the basic aberrations of defocus and astigmatism, the eye often has higher-order aberrations such as spherical aberration and other aberrations. Chromatic aberrations, aberrations due to varying focus with wavelength across the visible spectrum, are also present in the eye. These higher-order aberrations and chromatic aberrations negatively affect the quality of a person's vision. The negative effects of the higher-order and chromatic aberrations increase as the pupil size increases. Vision with these aberrations removed is often referred to as high definition (HD) vision.

Presbyopia is the condition where the eye loses its ability to focus on objects at different distances. Aphakic eyes have presbyopia. A standard monofocal IOL implanted in an aphakic eye will restore vision at a single focal distance. To provide good vision over a range of distances, a variety of options can be applied, among them, using a monofocal IOL combined with bi-focal or progressive addition spectacles. A monovision IOL system is another option to restore near and distance vision - one eye is set at a different focal length than the fellow eye, thus providing binocular summation of the two focal points and providing blended visions.

Monovision is currently the most common method of correcting presbyopia by using IOLs to correct the dominant eye for distance vision and the non-dominant eye for near vision in an attempt to achieve spectacle-free binocular vision from far to near. Additionally IOLs can be bifocal or multifocal. Most IOLs are designed to have one or more focal regions distributed within the addition range. However, using elements with a set of discrete foci is not the only possible strategy of design: the use of elements with extended depth of field (EDOF), that is, elements producing a continuous focal segment spanning the required addition, can also be considered. These methods are not entirely acceptable as stray light from the various focal regions degrade a person's vision.

What is needed in the art is an improved virtual aperture IOLto overcome these limitations.

According to <CIT> a narrow profile, glare reducing, posterior chamber intraocular lens comprises an optic having an anterior surface and a posterior surface and an optical axis. The posterior surface is formed having two adjacent periaxial, stepped imaging zones, the two imaging zones having the substantially the same optical power. A transition zone between the two imaging zones preferably has a surface of continuous curvature shaped to reduce direct glare from light incident on the transition zone in an individual's eye in which the intraocular lens is implanted by internal reflection of direct light incident on the transition zone. Attachment members joined to the optic position the intraocular lens in an eye with the optical axis of the optic generally aligned with the optical axis of the eye. In variations, the transition zones are formed at the optic edge to minimize direct and indirect in the eye of an individual wearing the intraocular lens.

Disclosed is a virtual aperture integrated into an intraocular lens (IOL). The construction and arrangement permit optical rays which intersect the virtual aperture and are widely scattered across the retina, causing the light to be virtually prevented from reaching detectable levels on the retina. The virtual aperture helps remove monochromatic and chromatic aberrations, yielding high-definition retinal images. For a given definition of acceptable vision, the depth of field is increased over a larger diameter optical zone IOL.

An objective of the invention is to teach a method of making thinner IOLs since the optical zone can have a smaller diameter, which allows smaller corneal incisions and easier implantation surgery.

Another objective of the invention is to teach a virtual aperture IOL that exhibits reduced monochromatic and chromatic aberrations, as well as an extended depth of field, while providing sufficient contrast for resolution of an image over a selected range of distances.

Still another objective of the invention is to teach a virtual aperture IOL that provides a smaller central thickness compared to other equal-powered IOLs.

Another objective of the invention is to teach a virtual aperture that can be realized as alternating high-power positive and negative lens profiles.

Yet still another objective of the invention is to teach a virtual aperture that can be realized as high-power negative lens surfaces.

Another objective of the invention is to teach a virtual aperture that can be realized as high-power negative lens surfaces in conjunction with alternating high-power positive and negative lens profiles.

Yet another objective of the invention is to teach a virtual aperture that can be realized as prism profiles in conjunction with alternating high-power positive and negative lens profiles.

An objective of the instant invention is to overcome these limitations by providing a phakic or aphakic IOL which simultaneously: provides correction of defocus and astigmatism, decreases higher-order and chromatic aberrations, and provides an extended depth of field to improve vision quality.

Another objective of the invention is to teach a virtual aperture that can be employed in phakic or aphakic IOLs, a corneal implant, a contact lens, or used in a cornea laser surgery (LASIK, PRK, etc.) procedure to provide an extended depth of field and/or to provide high-definition vision.

Another objective of the invention is to teach replacement of the virtual aperture with an actual opaque aperture and realize the same optical benefits as the virtual aperture.

Other objectives and further advantages and benefits associated with this invention will be apparent to those skilled in the art from the description, examples and claims which follow.

Detailed embodiments of the instant invention are disclosed herein; however, it is to be understood that the disclosed embodiments are merely exemplary of the invention, which may be embodied in various forms. Therefore, specific functional and structural details disclosed herein are not to be interpreted as limiting, but merely as a basis for the claims and as a representation basis for teaching one skilled in the art to variously employ the present invention in virtually any appropriately detailed structure.

<FIG> illustrates a single converging lens <NUM> centered on an optical axis <NUM>. An incident ray <NUM> is parallel to the optical axis and will intersect the focal point <NUM> of the lens. If the observation plane <NUM> is located a further distance from the focal point, the incident ray will continue until it intersects the observation plane. If we trace all incident rays with the same ray height as incident ray <NUM>, we will locate a blur circle <NUM> on the observation plane. Other incident rays with ray height less than incident ray <NUM> will fall inside this blur circle <NUM>. One such ray is incident ray <NUM> which is closer to the optical axis than incident ray <NUM>. Incident ray <NUM> also intersects the focal point <NUM> and then the observation plane <NUM>. Tracing all incident rays with a ray height equal to incident ray <NUM> traces out blur circle <NUM> which is smaller than blur circle <NUM>.

The optical principle represented here is that as the height of parallel incident rays is reduced, the corresponding blur circle is also reduced. This simple relationship is applicable to the human eye. Stated another way, for a given amount of defocus (dioptric error) in the eye, vision is improved as the height of incident rays is reduced. This principle is used when someone squints in an attempt to see an out-of-focus object more clearly.

The tracing in <FIG> is for a single wavelength of incident light. For polychromatic light, three wavelengths in this case, we have the situation in <FIG>. It is well known for the components of the eye and typical optical materials that, as wavelength increases, the refractive index decreases. In <FIG>, a converging lens <NUM> has optical axis <NUM>. An incident ray <NUM> consists of three wavelengths for blue (<NUM>), green (<NUM>), and red (<NUM>) light. Due to different indices of refraction for the three wavelengths, the blue light ray <NUM> is refracted more than the green light ray <NUM>, and the green light ray is refracted more than the red light ray <NUM>. If the green light ray is in focus, then it will cross the observation plane <NUM> at the optical axis. The chromatic spread of these three rays lead to a chromatic blur circle <NUM> on the observation plane. In <FIG>, the incident chromatic ray <NUM> has a lower ray height than the chromatic ray <NUM> in 2A. This leads to the smaller chromatic blur circle <NUM> at the observation plane. Thus, just as for the monochromatic of <FIG>, chromatic blur is decreased as the chromatic ray height is decreased.

<FIG> and <FIG> illustrate that decreasing ray height (decreasing the pupil diameter) decreases both monochromatic and chromatic aberrations at the retina, thus increasing the quality of vision. Another way to describe this is that the depth of field is increased as the ray height is decreased.

<FIG> illustrates a converging lens <NUM> with optical axis <NUM> and aperture <NUM>. Incident ray <NUM> clears the aperture and thus passes through the lens focal point <NUM> and intersects the observation plane <NUM> where it traces a small blur circle <NUM>. Incident ray <NUM> is blocked by the aperture, and thus it cannot continue to the observation plane to cause a larger blur circle <NUM>. An aperture which limits the incident ray height reduces the blur on the observation plane. In <FIG> we illustrate what we describe as a "virtual aperture". That is, it is not really an aperture that blocks rays, but the optical effect is nearly the same. Rays <NUM> which propagate through the virtual aperture <NUM> are widely spread out so there is very little contribution to stray light (blurring light) at any one spot on the observation plane. This is the principal mechanism of operation of the IOL invention.

<FIG> illustrates a basic layout of an IOL which employs the virtual aperture. In this figure, a central optical zone <NUM> provides correction of defocus, astigmatism, and any other correction required of the lens. Generally, for an IOL using a virtual aperture, the central optical zone diameter is smaller than a traditional IOL. This leads to a smaller central thickness which makes the IOL easier to implant and allows a smaller corneal incision during surgery. The virtual aperture <NUM> is positioned further in the periphery and the IOL haptic <NUM> is located in the far periphery. The virtual aperture is connected to the optical zone by transition region <NUM> and the haptic is connected to the virtual aperture by transition region <NUM>. The transition regions <NUM> and <NUM> are designed to ensure zero-order and first-order continuity of the surface on either side of the transition region. A common method to implement this is a polynomial function such as a cubic Bezier function. Transition methods such as these are known to those skilled in the art.

In the preferred embodiment, the virtual aperture zone <NUM> is a sequence of high-power positive and negative lens profiles. Thus, light rays which intersect this region are dispersed widely downstream from the IOL. These profiles could be realized as sequential conics, polynomials (such as Bezier functions), rational splines, diffractive profiles, or other similar profiles, as long as the entire region properly redirects and/or disperses the refracted rays. The preferred use is smooth high-power profiles over diffractive profiles as this simplifies manufacturing the IOL on a high-precision lathe or with molds. As known to those skilled in the art, the posterior side of the haptic should include a square edge to inhibit cell growth leading to posterior capsule opacification.

<FIG> illustrates another profile for the virtual aperture zone <NUM>, namely a diverging lens profile. Note that this requires a thicker edge profile than the approach in <FIG>. In <FIG> we show a close up of the preferred high-powered alternating positive and negative lens profiles with the incident and transmitted rays. <FIG> illustrates the effect of combining the profile in 6A with either an underlying prism or negative lens. In this case not only are the emergent rays scattered widely, they are directed away from the eye's macula, or central vision section of the retina, again, at the cost of a wider lens edge.

<FIG> illustrates a high-power IOL <NUM>, usually with a relatively small optical diameter and large central thickness. When the eye's pupil is larger than the optical zone, incident rays <NUM> can miss the optic entirely and only intersect the haptic <NUM> on their way to the retina <NUM>. This situation would cause noticeable artifacts in the peripheral vision of the eye. Incident rays <NUM>, which intersect the optic zone as expected, are correctly refracted to the central vision of the retina. In <FIG> we illustrate the same optic, but now with a virtual aperture <NUM> between the optic and the haptic. In this case, incident rays <NUM> which intersect the lens outside of the optical zone, are dispersed across the retina causing no apparent artifacts.

Taken together, these characteristics of an IOL which incorporates the virtual aperture can accurately be described as high definition (HD) and extended depth of field (EDOF).

The basic layout of the virtual aperture IOL is illustrated in <FIG>. In the preferred embodiment, the diameter of the central optical zone <NUM> is <NUM> and the width of the virtual aperture <NUM> is <NUM>. Thus, the combination of central optical zone and virtual aperture is a <NUM>-mm diameter optic, which is similar to common commercially available IOLs.

The central optical zone can be designed using standard IOL design concepts to provide sphere, cylinder, and axis correction, as well as higher-order correction such as spherical aberration control. These design concepts are known to those skilled in the art.

The preferred virtual aperture profiles illustrated in <FIG> have alternating positive and negative lens profiles with focal lengths on the order of +/- <NUM>. These lens surface profiles can be generated using conics, polynomials (such as cubic Bezier splines), rational splines, and combinations of these and other curves. The geometry of the lens profiles is selected to adequately disperse the transmitted optical rays across the retina and at the same time be relatively easy to manufacture on a high-precision lathe or with a mold process. It is also possible to place a smooth surface on one profile (for example the front surface) and the small high-power lens profiles on the other surface profile (for example the back surface).

Using the preferred virtual aperture profiles illustrated in <FIG>, the edge thickness of the IOL and the center thickness of the central optical zone can be quite small, even for high-power IOLs. The material of the lens is the same as those used for other soft or hard IOL designs.

The IOL design provides very good, high-definition, distance vision and the range of "clear vision" can be controlled by specification of what is meant by "clear vision" (e.g., <NUM>/<NUM> acuity), and the relative size of the central optic zone and the virtual aperture width. A simple equation [<NPL>] for estimating the acuity given the pupil diameter and spherical refractive error is given in equation (1a and 1b). <MAT> <MAT>.

The second equation is postulated as being more accurate for low levels of refractive error, and gives a reasonable result.

The concept of the virtual aperture can be employed in phakic or aphakic IOLs, a corneal implant, a contact lens, or used in a cornea laser surgery (LASIK, PRK, etc.) procedure to provide an extended depth of field and/or to provide high-definition vision. Also, it would be possible to replace the virtual aperture with an actual opaque aperture and realize the same optical benefits as the virtual aperture.

It is to be understood that while a certain form of the invention is illustrated, it is not to be limited to the specific form or arrangement herein described and shown. It will be apparent to those skilled in the art that various changes may be made within the scope of the claims and the invention is not to be considered limited to what is shown and described in the specification and any drawings/figures included herein.

Claim 1:
An intraocular lens (<NUM>) for providing high definition and extended depth of field, said intraocular lens comprising:
a central optical zone (<NUM>) formed integral into said intraocular lens;
a virtual aperture (<NUM>) positioned in a first periphery region surrounding said central optical zone (<NUM>) and connected to said optical zone by a first transition region (<NUM>); and
a haptic (<NUM>) positioned in a far periphery and connected to said virtual aperture (<NUM>) by a second transition region (<NUM>) ;
characterized in that
said first and second transition regions (<NUM>, <NUM>) having a zero-order and first-order continuity of the surface on either side of said first and second transition regions (<NUM>, <NUM>);
wherein said virtual aperture (<NUM>) comprises alternating high-power positive and negative lens profiles; and
wherein a plurality of light rays which intersect the virtual aperture are dispersed widely downstream from the intraocular lens (<NUM>).