The present invention pertains to the group of intraocular aberration correction lens. The intervention refers to an intraocular lens that presents a calculated optical power in such a way that it provides an emmetropic refractive state,
The lens can replace the natural crystalline, either because of loss of transparency, the capacity to adjust its power, or to correct the refractive state of the eye, to enable correct vision without other optical supports. The lens can also be implanted while maintaining the patient's crystalline, in which case it is only used to correct the refractive state of the eye.
Therefore, the present intervention pertains to the field of medical prostheses that are implanted inside the eye.
Aberrations
In general, a chromatic aberration is understood to be the deviation of an optical system in relation to its ideal behaviour as the consequence of the change in the index, or indexes, of refraction, depending on the colour, frequency or wavelength of the light traversing it. For studying it, the chromatic aberration is generally divided into two, with attention to the object that produces them. Therefore, the longitudinal aberration is established for momentary objects and on the eye, as a difference in the focal plane depending on the wavelength of the light used. For momentary objects outside the eye, or extended objects, a transversal, lateral or increased chromatic aberration is used. This produces a change in the position or size of the images, depending on wavelength used. All means, except a vacuum, present change in its reflection index to a greater or lessor extent, depending on the wavelength used. This phenomenon is called chromatic dispersion. Different parametrized equations are usually used for its characterization, such as, for example, the Cauchy or Sellmeier equation. Using the Abbe number as a simplified way is also commonplace, with a single value for indicating if a material is more or less dispersive. The Abbe number is mathematically defined as:
V
d=n
where nd, nF y nc are the refraction indexes of the material in the wavelengths corresponding to the so called Fraunhofer lines d, F and C, that numerically correspond to 587.6 nm, 486.1 nm and 656.3 nm, respectively. Throughout this document, when it is indicated that one material is more or less dispersive than another, it must be understood in the sense of exhibiting a smaller or greater Abbe number, respectively, than the one taken as the comparison.
The eye, through the different optical means comprising it, such as the aqueous humour, vitreous humour, etc., presents a notable chromatic dispersion. Therefore, the images it produces on the retina are affected by a significant amount of chromatic aberration. As such, short wavelengths, which correspond to blue tones in the visible spectrum, are focused in front of those long wavelengths corresponding to reddish tones in the visible spectrum.
On the other hand, the aberrations called monochromatic aberrations are the ones that appear without the need of considering the chromatic dispersion of the mean or means that comprise the optic system, in a deviation shape with respect to the ideal or paraxial behaviour of the system. For study purposes, the ones usually classified as point or centre aberrations are the ones produced by momentary objects on the optical axis, and extra-axial or outside the axis aberrations, that arise as a consequence of the consideration of momentary objects outside the optic axis, or objects or extended scenes that cover a certain field in the subject space. Specifically, these are called field aberrations.
The human eye, understood as an image forming system, suffers from aberrations inside and outside the optic axis, as well as the previously mentioned chromatic aberrations that limit the optic quality of the images projected on the retina. Wth respect of the ideal behaviour, these deviations have an important relevance in the visual quality, with special impact on the peripheral vision.
Intraocular Lens
At present, surgical implantation of intraocular lens, to replace the natural crystalline after a cataract operation, and as an ametropias corrector element like myopia or astigmatism in the anterior chamber of the eye, constitutes a routine practice. As detailed in the work of D. J. Apple and D. Sims, “Harold Ridley and the invention of the intraocular lens,” Survey of Ophthalmology 40, 279-292 (1996), the technique was introduced by Ridley in 1945, based on the experience he acquired treating traumas military pilots suffered as a consequence of combat in the World War Two. Intraocular lens in their most extended form are designed to correct a patient's farsightedness. These are called monofocal lenses, because they are made with a single optical power. There are different formulas for obtaining the adequate power to correct the patient's farsightedness. These formulas require first measuring some biometric parameters of the eye, such as axial length, length of the anterior chamber, or an estimate of the position of the implanted lens. Some include the refraction of the object displays. The majority of people with implanted intraocular lens do not need additional corrections with glasses or contact lenses to correctly see far. Ideally, an intraocular lens should provide clear vision at every distance, just as the natural crystalline does for the large part of a lifetime. When the eye does not accommodate, it is called presbyopic. This capacity to accommodate is lost with age, and so the inclusion of this multifocality characteristic in the intraocular lens is of capital importance. In effect, the capacity to focus clearly on scenes at different distances is basic, and gives people quality of life and well-being. It is estimated that approximately 80% of the information a human being handles in industrialised societies is obtained by sight. This also occurs with short-sightedness, and mid-sightedness.
There are numerous alternatives for manufacturing intraocular lens. The following are some patents related to the present invention:
U.S. Pat. No. 7,241,009 B2, U.S. Pat. No. 7,837,326 B2, US 2011/0071 628 A1, US2002/0107 568 A1 and US 2006/0271 187 A1, US 2004/0015 236 A1, US2010/0211 171 A1, US 2011/0035001 A1, U.S. Pat. No. 7,871,437 B2, US 6,217,619 B1, US 2003/0187 505 A1, US 2004/0249 456 A1, US 2005/0125058 A1 and US 2005/0107875 A1. US 2008/0154 363 A1. U.S. Pat. No. 6,638,306 B2, US 2007/0129 801 A1, 2005/0107 875 A1, US 2008/0027 538 A1, US 2009/0234 449 A1, US 2010/0228 346 A1, U.S. Pat. No. 7,217,288 B2, U.S. Pat. No. 7,261,737 B2, U.S. Pat. No. 7,220,279 B2, US 5 58 572 A, US 2010/0100177A1, US 005 112 351 A, US 007 481 532 B2, US 2009/0240 328 A1, US 20 100 097 569 A1. EP0329981A1, EP1862147A1, U.S. Pat. No. 5,201,762, U.S. Pat. No. 6,391,230, US20110037184A1, US20140180409, US20070004863, U.S. Pat. No. 5,152,787, U.S. Pat. No. 6,695,880, US20120310340,
Many intraocular lens and optical elements of the prior art use a gradient in their refraction index, and incorporate variations in their values, as a function of the distance to the optical axis.
The subject matter of the invention is to provide an aberration correction intraocular lens that can provide quality and clear vision free of chromatic and monochromatic aberrations within a wide field of view, improved in comparison with the vision provided by the intraocular lenses of the prior art.
The invention provides an intraocular aberration correction lens that comprises mechanical fasteners for implanting the lens in the interior of the eye, in which its optical area comprises at least a material that makes said optical area present a gradient in the chromatic dispersion in the direction of the optical axis, the effective value of the chromatic dispersion being different in the anterior area of the lens, which is the area most proximate to the cornea of the eye after the lens implantation, from that in the area posterior to the lens, which is the area most proximate to the retina of the eye after the lens is implanted.
The invention, therefore, consists in an intraocular lens made of a material or materials that present a gradient in its chromatic dispersion, in contrast to or as a novelty with respect of lenses and optical elements that use a gradient in their refraction index. Furthermore, this gradient can only be introduced in a direction that coincides with the optical axis of the eye; also as a novelty and advantage compared to lenses with an index gradient that incorporates variations in their values as a function of the distance to the optical axis.
The subject intraocular lens of the invention also has the possibility incorporated of correcting or manipulating the monochromatic aberrations with adequate carving of the available surfaces. The flexibility in the manufacturing of this new intraocular lens enables not only correcting or significantly reducing, or ultimately manipulating, the usual aberrations on the optical axis of the eye, but also the eccentric aberrations outside the axis or field that are present in the eye and which, to date, have never been compensated or altered in a controlled manner. The simultaneous correction or manipulation of the chromatic and monochromatic aberrations provide a significant increase in the patient's visual quality, and notably increments the depth of field. The latter makes possible a clear vision of scenes placed at various distances. To this end, the incorporation of mulitfocal areas on this material support with chromatic dispersion gradient, involves an advance and a clear advantage over the current state of the art, given that it is possible to reduce the power addition needed in order to be able to see at a determined distance by the effect of increasing the depth of field. This greatly contributes to an improved visual quality that can be quantified as an increase in visual acuity, in sensitivity to contrast in photopic conditions, high illumination like scotopics, or low illumination.
The following will illustrate, but not limit, the subject matter of the present invention, making reference to the accompanying drawings, which are:
The present invention consists in a lens and its corresponding fastener 26, 27 (see
To attain the correction, or a significant decrease of the chromatic aberrations, optical area 1 of the intraocular lens, as displayed in
One of the simplest embodiments of the invention is one that only uses two materials with different chromatic dispersions, which would provoke the apparition of a separation or transition surface between them 4, o also with a single material with a continuous chromatic dispersion gradient. The combination of two materials, with each one showing a certain chromatic dispersion gradient, is also possible for the practical embodiment of the invention, as long as the net effect is a change between the values of the chromatic dispersion between the anterior and posterior areas. The minimum requirement, therefore, is that the chromatic dispersion gradient evolves along the optical axis, although variations in other directions are also acceptable.
Another very interesting practical alternative for the internal distribution of the chromatic dispersion of the material that shapes the intraocular lens, is displayed schematically in
The subject intraocular lens of the present invention can be given multifocal capacity adding areas that display different optical power, as displayed in
When producing areas that enable multifocality, one alternative is the sole use, or in combination, of the Fresnel profiles, also known as diffractive profiles. This is displayed schematically in
The subject intraocular lens of the present invention can be surgically placed in the anterior chamber of the eye or in the posterior chamber without loss of advantages, as shown in
The intraocular lens can be implanted to substitute the crystalline, or in conjunction with it, in what is known as a phakic lens, In both cases, the quality of the retinal images experience the advantages proper of the invention described herein.
In another embodiment of the intraocular lens of the invention, some of the materials that enable the generation of a chromatic dispersion gradient are separated from the rest of the materials that shape the lens and, therefore, surrounded by aqueous humour after the lens is implanted in the eye.
Materials
Currently there is a broad range of possibilities regarding the materials that can be used in the intraocular lens. The current state of the art shows a large diversity of alternatives in the polymers family. Polymers, which consist in molecular chains whose fundamental unity is repeated in order to shape the structure of the material, constitute a preferred option. The macroscopic properties of the polymer, such as its refraction index, chromatic dispersion, water content, mechanical properties, etc., are determined by the properties of the so called base polymer molecule, as well as the way this molecule links to adjacent companions in the chain. The most used polymers in the ophthalmic optical field are the water-repellent and hydrophilic acrylics, and the silicones. Due to the nature of the intraocular lens disclosed herein and invented for use inside the eye of a patient, use of a biocompatible polymer, which has an inert behaviour once implanted inside the human body, is mandatory. There are numerous techniques that enable controlled variation of the chromatic dispersion of polymer materials, either during manufacturing or during the curing or maturing process prior to its carving or injection.
Technology enables manipulating the refraction indexes and the chromatic dispersions of the polymers for obtaining similar values starting from silicones or acrylic materials. Consequently, as regards materials the preferred embodiment of this invention does not need the detailed determination of the material type for its execution. Different alternatives give the same effect and benefit.
An alternative to using the usual polymers as regards the materials that shape the optical area of the intraocular lens, is the use of photopolymerizable materials. These open the possibility of being able to adjust its chromatic dispersion, refraction index, and even the geometrical shape, with controlled irradiation of ultraviolet light. The big advantage is that this polymerization can be carried out after implantation inside the eye of the patient. In this way there is a very high percentage of success in terms of the refraction obtained in the end. The use of this type of photopolymerizable material can be done in any of the materials of the lens, or several of them, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, simultaneously. For this, the material closest to the anterior pole of the eye would have to be photopolymerized first, in order to progressively continue actuating on the rearmost materials. In any event, for the correct execution of this modality, the incorporation of an ultraviolet light filter is necessary for preventing the radiation used in the photopolymerization from reaching the retina of the subject.
The ultraviolet filter can be incorporated on the intraocular lens in any of the dioptres that comprise it, and there is no reason for its use to be linked to the use of photopolymerizable materials. In fact, its use is beneficial to the patient in every case, in as much it protects the cells of the retina of this portion of the spectrum, which is associated with various types of pathological degenerations.
There are numerous alternatives for the mechanical fasteners or haptics 26 and 27, that do not affect the properties and advantages of the present invention. As such, it can be used for the embodiment of the PMMA, polypropylene, polyamide, and vinylidene, poly fluoride or PVDF, or combinations thereof. All these previously disclosed materials are routinely used for manufacturing haptics in the field of intraocular lens.
A detailed description of the invention has been made with its preferred embodiments, as well as alternatives in many cases. However, there are other relatively evident modifications or variations that are obvious to an expert in the field of intraocular lens design, that have not been explicitly included. These other possible embodiments that are based on the same principles and ideas displayed in the present invention must also be understood as covered and protected by the present document.
The following numeric references are linked to the different elements described and represented in the present document:
Number | Date | Country | Kind |
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201630234 | Feb 2016 | ES | national |