INTRAOCULAR LENS AND METHODS FOR OPTIMIZATION OF DEPTH OF FOCUS AND THE IMAGE QUALITY IN THE PERIPHERY OF THE VISUAL FIELD

Abstract

Intraocular lens and methods for optimization of depth of focus and the image quality in the periphery of the visual field. The intraocular lens (600) comprises a central part and a peripheral part, the central part being the optical part (600) and the peripheral part comprising mechanical fasteners (603), and the central part comprises: an aspherical concave anterior surface (601), which is the surface closest to the iris of the eye once the lens (600) has been implanted in the eye, and an aspherical convex posterior surface (602), which is the surface closest to the retina of the eye once the lens (600) has been implanted in the eye, such that the radius of curvature of the posterior surface (602) of the central part is smaller than the radius of curvature of the anterior surface (601) of the central part, with a ratio between radii of between 2 and 6, and the mechanical fasteners (603) are arranged at an angle (605) of between 0° and 10° with respect to a plane passing through the joints between the central part and the peripheral part and which is perpendicular to the optical axis of the eye in which the lens (600) is intended to be implanted.

Claims

1. Method to optimize depth of focus and the quality of the image in the periphery of the visual field, which uses intraocular lenses (600) comprising a central part and a peripheral part, the central part being the optical part and the peripheral part comprising mechanical fasteners wherein the central part comprises: an aspherical concave anterior surface), which is the surface closest to the iris of the eye once the lens has been implanted in the eye, and an aspherical convex posterior surface, which is the surface closest to the retina of the eye once the lens (600) has been implanted in the eye, such that: the radius of curvature of the posterior surface of the central part is smaller than the radius of curvature of the anterior surface of the central part, with a ratio between radii of between 2:1 and 6:1, and the mechanical fasteners (603) are arranged at an angle (605) of between 0 and 10° with respect to a plane passing through the intersections between the central part and the peripheral part and which is perpendicular to the optical axis of the eye in which the lens (600) is intended to be implanted. wherein the method comprises the following steps: to provide a series of intraocular lenses (600) of different net asphericity value, to place a patient (700) in front of a visual simulator (800) of adaptive optics, which emulates different intraocular lens profiles with different net asphericity value, realization of different simulations (900) with different intraocular lens profiles through a visual test at different distances, selection of the optimal result (901) of the visual test, and determination of the net asphericity value of the intraocular lens, and choice of the intraocular lens (600) presenting the determined net asphericity value for its implantation in the patient's eye (700).

2. Method to optimize depth of focus and the quality of the image in the periphery of the visual field according to claim 1 wherein said intraocular lenses are ones in which the mechanical fasteners (603) are arranged at an angle (605) of 2° with respect to a plane passing through the joints between the central part and the peripheral part and which is perpendicular to the optical axis of the eye in which the lens (600) is intended to be implanted.

3. Method to optimize depth of focus and the quality of the image in the periphery of the visual field according to claim 1 in which the intraocular lenses are ones in which the central part has a circular aspect.

4. Method to optimize depth of focus and the quality of the image in the periphery of the visual field according to claim 1 in which the intraocular lenses are ones in which the central part has an oval aspect.

5. Method to optimize depth of focus and the quality of the image in the periphery of the visual field, which uses intraocular lenses (600) comprising a central part and a peripheral part, the central part being the optical part and the peripheral part comprising mechanical fasteners wherein the central part comprises: an aspherical concave anterior surface), which is the surface closest to the iris of the eye once the lens has been implanted in the eye, and an aspherical convex posterior surface, which is the surface closest to the retina of the eye once the lens (600) has been implanted in the eye, such that: the radius of curvature of the posterior surface of the central part is smaller than the radius of curvature of the anterior surface of the central part, with a ratio between radii of between 2:1 and 6:1, and the mechanical fasteners (603) are arranged at an angle (605) of between 0° and 10° with respect to a plane passing through the intersections between the central part and the peripheral part and which is perpendicular to the optical axis of the eye in which the lens (600) is intended to be implanted wherein said method comprises the following steps: measurement of eye shape and/or refraction at the periphery, and depending on the measurements made, to customise the shape of the intraocular lens (600) and its net asphericity for its implantation in the patient's eye (700).

6. Method to optimize depth of focus and the quality of the image in the periphery of the visual field, according to claim 5 wherein said intraocular lenses are ones in which the mechanical fasteners (603) are arranged at an angle (605) of 2° with respect to a plane passing through the joints between the central part and the peripheral part and which is perpendicular to the optical axis of the eye in which the lens (600) is intended to be implanted.

7. Method to optimize depth of focus and the quality of the image in the periphery of the visual field according to claim 5 in which the intraocular lenses are ones in which the central part has a circular or oval aspect.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0030] The object of the present invention will be illustrated below in a non-limiting way, making reference to the drawings that are accompanied, in which:

[0031] FIG. 1 shows a section of a human eye and the focusing of objects in the center of the visual field, and on the periphery of the visual field.

[0032] FIG. 2 shows a section of a human eye with a prior art intraocular lens implanted in the posterior chamber of the eye, and the focusing of objects in the center of the visual field and on the periphery of the visual field.

[0033] FIG. 3 shows a section of a human eye with an intraocular lens of the invention implanted in the posterior chamber of the eye, and the focusing of objects in the center of the visual field and on the periphery of the visual field.

[0034] FIG. 4A shows one embodiment of an intraocular lens according to the invention.

[0035] FIG. 4B shows another embodiment of an intraocular lens according to the invention.

[0036] FIG. 5 schematically shows a visual simulator of adaptive optics and its use in the method to optimize depth of focus and image quality at the periphery of the visual field of invention.

DETAILED DESCRIPTION OF THE INVENTION

[0037] FIG. 1 shows a section of the human eye. The light 500 entering through the pupil is focused by the cornea 100 and the lens of the crystalline 300 on the retina 200. Objects in the center of the visual field are focused on the central part 201 of the retina, while objects on the periphery of the visual field are focused on a peripheral point 202 of the retina.

[0038] FIG. 2 shows an eye with a prior art intraocular lens 400 implanted in the posterior chamber of the eye. The light 500 entering through the pupil is focused by the cornea 100 on the retina 200. The intraocular lens 400 has an anterior surface 401, a posterior surface 402 and mechanical fasteners or haptics 403. Objects in the center of the visual field are focused on the central part 201 of the retina, while objects on the periphery of the visual field are focused on a peripheral point 203 of the retina. This peripheral point 203 is generally different from the peripheral focus point 202 prior to cataract surgery. In addition, rays entering the eye from the periphery of the visual field are strongly aberrated and the image at peripheral point 203 is out of focus.

[0039] FIG. 3 shows an intraocular lens 600 of the invention implanted in the posterior chamber of the eye. An eye is depicted with an improved intraocular lens 600, implanted in the posterior chamber. The light 500 entering through the pupil is focused by the cornea 100 on the retina 200. The intraocular lens 600 has an anterior surface 601, a posterior surface 602, an optical zone 610, and mechanical fasteners (haptics) 603. Objects in the center of the visual field are focused on the central part 201 of the retina, while objects in the periphery of the visual field are focused on a peripheral point 204 of the retina. This peripheral point 204 is close to the peripheral focus point 202 prior to cataract surgery. In addition, rays entering the eye from the periphery of the visual field are less aberrated and the image at peripheral point 204 is more focused.

[0040] FIGS. 4A and 4B show two embodiments of intraocular lenses of the invention. FIG. 4A shows the intraocular lens 600, with an anterior zone 601 that is concave and a posterior zone 602 that is convex, its optical zone 610, about 6 mm in diameter, and the mechanical fasteners (haptics) 603. FIG. 4B shows the mechanical fasteners (haptics) 604 with a certain angle 605 to a plane passing through the junctions between the central part and the peripheral part. This plane shall be perpendicular to the optical axis of the eye in which the lens is intended to be implanted.

[0041] FIG. 5 shows an adaptive optics visual simulator 800, which simulates different profiles of intraocular lenses 600 for a patient 700. The patient 700 evaluates the results of the simulations 900 through a visual test at different distances (i.e. far, intermediate, close) and chooses the most optimal result 901 according to his/her visual necessities. This is used to determine the net value of asphericity on the IOL to be implanted.

[0042] The present invention refers to the design of a new posterior chamber intraocular lens 600 that simulates the image formation properties of the natural crystalline lens, in the specific referring to the induced field curvature and to the improvement of the visual quality on the far periphery of the retina. Moreover, it can offer extended depth of focus both for central and peripheral vision and therefore reduce the dependence on spectacles postoperatively as well as allow for variability of the shape of peripheral retina. The IOL 600 is manufactured from one of the existing materials suitable of intraocular implantation such as hydrophobic acrylic, hydrophilic acrylic, silicone and can be produced either by machining or by molding.

[0043] The intraocular lens 600 has a central part with a diameter between 5 and 7 mm (preferably around 6 mm), with the required optical properties, and a peripheral part that extends to a diameter between approximately 10 and 14 mm (the haptics or mechanical fasteners 603) that help center and, stabilize the intraocular lens 600 in the lens capsule once the cataract crystalline lens has been removed. The haptics 603 are selected from a range of designs established in the scientific literature. In the surgical process, the lens 600 is bent and injected into the prepared capsule through a small incision in the limbus or peripheral cornea.

[0044] In an embodiment of the intraocular lens 600, it is manufactured by molding acrylic hydrophobic material with a refractive index of approximately 1.53. The anterior surface 601 of the intraocular lens 600 is concave aspherical, and the posterior surface 602 is convex aspherical. The optical part 610 of the lens 600 is circular and has a diameter of approximately 6 mm. The anterior surface 601 has a negative power when submerged in the aqueous humour of the eye (or a similar aqueous solution, such as saline solution), while the posterior surface 602 has a positive power. The combination of these two surfaces produces a refractive power of the order of 20 D when the intraocular lens 600 is immersed in the aqueous humour of the eye (or a similar aqueous solution, such as saline). The radius of curvature of the anterior surface 601 can be changed to produce intraocular lenses 600 of the same type, but with different diopter powers, as required in cataract surgery. The posterior surface 602 has an appropriate conical constant such that the spherical aberration of the lens 600 compensates for the spherical aberration of the average cornea of a human eye. In this embodiment, the total spherical aberration of the eye is practically zero, achieving optimal image quality for central and peripheral vision. The haptics 603 form an angle 605 (see FIG. 4b) with respect to a plane passing through the junctions between the central part and the peripheral part and which is perpendicular to the optical axis of the eye in which the lens 600 of approximately 2 degrees is intended to be implanted.

[0045] In another embodiment of the present invention, the intraocular lens 600 is manufactured by machining or molding hydrophobic acrylic material with a refractive index of between about 1.46 to about 1.55. The anterior surface 601 of the intraocular lens 600 is concave aspherical and the posterior surface 602 is convex aspherical. The optical part 610 of the lens 600 is circular and has a diameter of approximately 5 to 7 mm. The anterior surface 601 has a negative power when submerged in the aqueous humour of the eye (or a similar aqueous solution, such as saline solution), while the posterior surface 602 has a positive power. The combination of these two surfaces produces a refractive power of the order of 20 D when the intraocular lens 600 is immersed in the aqueous humour of the eye (or a similar aqueous solution, such as saline). The radius of curvature of the anterior surface 601 can be changed to produce intraocular lenses 600 of the same type, but with different diopter powers, as required in cataract surgery. The posterior surface 602 has an appropriate conical constant such that the total power of the intraocular lens 600 remains constant, but that the negative spherical aberration of the lens 600 induces a concrete value equal to or greater (in absolute value) than that of the average cornea of a human eye. In this embodiment, the total spherical aberration of the eye can be adjusted between values close to zero and a negative value approximately 5 times greater (in magnitude) than that of the average cornea of a human eye. In this way, a greater compromise between image quality and depth of focus can be achieved. The optical part 610 has a diameter of approximately 6 mm and the haptics 603 form an angle 605 with respect to a plane that passes through the joints between the central part and the peripheral part and that is perpendicular to the optical axis of the eye in which the lens 600 is to be implanted, which varies between 0 and approximately 10°.

[0046] In another embodiment, the intraocular lens 600 is manufactured by machining or molding any material in the hydrophobic acrylic, hydrophilic acrylic, or silicone group that has refractive indices typically between approximately 1.46 and approximately 1.55. The anterior surface 601 of the intraocular lens 600 is concave aspherical and the posterior surface 602 is aspherical convex. The optical part 610 of the lens 600 is circular and has a diameter ranging from approximately 5 to 7 mm. The anterior surface 601 has a negative power when submerged in the aqueous humour of the eye (or a similar aqueous solution, such as saline solution), while the posterior surface 602 has a positive power. The combination of these two surfaces produces a refractive power of the order of 20 D when the intraocular lens 600 is immersed in the aqueous humour of the eye (or a similar aqueous solution, such as saline). The radius of curvature of the anterior surface 601 can be changed to produce intraocular lenses 600 of the same type, but with different diopter powers, as required in cataract surgery. The balance of diopter power between the anterior 601 and posterior 602 surfaces can be changed to compensate for total or partial peripheral astigmatism in the eye. Both surfaces, anterior 601 and posterior 602, may have conical constants defined in such a way that the power of the intraocular lens 600 remains almost constant but the negative spherical aberration of the lens 600 has a particular value equal to or greater (in absolute value) than that of the average human cornea. In this embodiment, the total spherical aberration in the eye can be adjusted from practically zero to a value approximately 5 times greater than the spherical aberration value of the normal eye (in absolute value). In this way, the best compromise between image quality and depth of focus is achieved. The optical zone 601 has a diameter of approximately 6 mm and the haptics 603 form an angle 605 with respect to a plane passing through the joints between the central part and the peripheral part and which is perpendicular to the optical axis of the eye in which the lens 600 is to be implanted, which varies between approximately 0 and approximately 10 degrees. The angulation 605 of the 603 haptics 603 controls the axial depth at which the intraocular lens 600 is implanted into the lens capsule. This adjustment, combined with the power balance between the anterior surface 601 and the posterior surface 602 can be varied to control the shape of the field curvature in the eye and make it match the shape of the retina. This adjustment helps correct peripheral refractive errors in the eye, a task that may be of particular importance for the control of myopia development following congenital cataract surgery. In a similar embodiment, the optical part 610 of the lens 600 can be oval. The longest axis of the oval would be implanted horizontally to reduce the phenomena associated with light diffusion and glare produced by the edge of the lens 600 in the distant temporal field of vision.

[0047] In another embodiment, the lens 600 is manufactured with one of the materials mentioned above, the anterior surface 601 of the lens 600 being concave aspherical and the posterior surface 602 being convex aspherical. The optical part 610 of the lens 600 is circular and has a diameter between approximately 5 and 7 mm. The central and peripheral refraction of a patient 700 is measured, as well as the topography of his cornea and the central and peripheral biometrics. Corneal topography information, the axial placement provided for the intraocular lens 600 during implantation, as well as central and peripheral biometrics are used to select from a range the angulation 605 of the haptics 603 and the balance between the anterior 601 and posterior 602 surface curvature radii to induce a desired central and peripheral post operative refraction.

[0048] In another embodiment, the lens 600 is manufactured with one of the materials mentioned above, the anterior surface 601 of the lens 600 being concave aspherical and the posterior surface 602 being convex aspherical. The optical part 610 of the lens 600 is circular and has a diameter of between approximately 5 mm to approximately 7 mm. The vision of patient 700 can be evaluated thanks to an adaptive optics simulator 800, in which a specific amount of spherical aberration (typically negative) is determined to optimize each patient individually. The optimization aims at maximizing the depth of focus without significantly sacrificing the quality of distant vision. When this value is determined, the patients corneal topography and biometry are used to select from a range of available intraocular lenses 600 that have different conical constants on at least one of the surfaces 601 or 602, to provide adequate post-operative refraction and depth of field.

[0049] A method for optimizing depth of focus and the image quality in the periphery of the visual field uses intraocular lenses 600 of those described above and comprises the following steps (FIG. 5): [0050] to provide a series of intraocular lenses 600 of different net asphericity value, [0051] to place a patient 700 in front of a visual simulator 800 with adaptive optics, which emulates different intraocular lens profiles with different net asphericity value, [0052] realization of different simulations 900 with different intraocular lens profiles through a visual test at different distances, [0053] selection of the optimal result 901 of the visual test, and determination of the net asphericity value of the intraocular lens, and [0054] choice of the intraocular lens 600 presenting the determined net asphericity value, for implantation in the eye of patient 700.

[0055] Another method for optimizing depth of focus and image quality at the periphery of the visual field uses intraocular lenses 600 of those described above and comprises the following steps: [0056] measurement of eye shape and/or refraction at the periphery, and [0057] depending on the measurements made, to customize the shape of the intraocular lens 600 and its net asphericity, for its implantation in the eye of patient 700.

[0058] Although some embodiments of the invention have been described and represented, it is clear that modifications can be made to them within its scope, which should not be considered to be limited to those embodiments, but only to the content of the following claims.