Intraocular lens for cataract surgery

Abstract

Intraocular lens for cataract surgery, comprising an anterior surface and a posterior surface, such that they form a meniscus with the anterior surface being concave and the posterior surface being convex, wherein: the shape factor is between -1 and -2, the anterior surface has a conic constant between 5 and 50, and the posterior surface has a conic constant between -5 and -2. This design of the intraocular lens for cataract surgery of the invention minimizes or even eliminate the occurrence of the entoptic phenomena caused by peripheral light sources after cataract surgery.

Description

[0001] DESCRIPTION

[0002] Intraocular lens for cataract surgery

[0003] Field of the invention

[0004] The present invention relates to ophthalmology and in particular to an intraocular lens (IOL), particularly for cataract surgery. The invention relates to a novel IOL design that overcomes the entoptic phenomena that characterize existing intraocular lenses.

[0005] Background of the invention

[0006] Cataracts are a medical condition in which the lens of the eye loses its transparency, resulting in a deterioration of the retinal image due to increased light scattering and aberrations. During cataract surgery, the damaged lens is removed from the eye, and a specialized implant known as an intraocular lens (IOL) is inserted to replace the refractive ability of the lens. IOLs have been used in ophthalmology for over fifty years and have become the most common and successful procedure not only in ophthalmology but throughout the entire field of medicine. The IOL chosen is carefully selected to provide the necessary refractive power, optimizing focusing on the retina and effectively replacing the patient's natural lens.

[0007] As a result of this implantation, the central visual field of the eye with an IOL (pseudophakic eye) is characterized by excellent image quality, limited mainly by any residual postoperative spherocylindrical error and, in some cases, by spherical aberration, depending on the type of IOL used.

[0008] Intraocular lenses (IOLs) play a crucial role in restoring adequate vision after cataract extraction. Due to the minimally invasive nature of both cataract extraction and IOL implantation procedures, these lenses are designed to be small in diameter and flexible, allowing them to be folded for easy insertion.

[0009] The small size of these IOLs is usually adequate for covering the pupil under normal lighting conditions, especially in elderly patients. However, under certain peripheral lighting conditions, for example, during night driving, the edges of the IOL can be illuminated by these peripheral light sources, leading to the appearance of various entoptic phenomena.

[0010] Entoptic phenomena associated with the limited diameter (usually 6 mm) of the IOL can be grouped into two categories: a) Positive dysphotopsias, in which the edge of the IOL reflects incoming light from peripheral light sources into the central visual field, and b) Negative dysphotopsias, in which some light is transmitted through the IOL optic and some light is lost, causing the incoming light to split into two distinct peaks and resulting in a dark band between them.

[0011] It should be noted that the IOL optic cannot be arbitrarily implanted near the iris opening, since mechanical contact with the iris must be avoided as this may be associated with, among other things, pigment dispersion, uveitis, inflammation and increased intraocular pressure.

[0012] The intraocular lens is implanted in the empty lens capsule after phacoemulsification and cataract extraction. Physically, the empty capsule collapses to a depth of approximately 1 mm behind the iris, exposing the edge of the IOL to incoming light from light sources in the peripheral visual field.

[0013] To mitigate these phenomena, US20080269890A1 ("Intraocular Lens with Peripheral Region Designed to Reduce Negative Dysphotopsia") describes a peripheral portion near the edge of the IOL capable of diffusing light reaching the edge of the IOL. US200802698890A1 also describes a haptic design with diffusing properties and a special peripheral transition zone on the posterior surface of the lens (US20080269885A1, "IOL Peripheral Surface Designs to Reduce Negative Dysphotopsia") that will refract light from peripheral sources.

[0014] Document W02020083829A1 ("Intraocular Lenses for Reducing Negative Dysphotopsia") describes an intraocular lens system that allows adjustable inclination of the IOL to reduce the dysphotopsia phenomenon. Document WO2022189994A1 ("Intraocular Lenses for Reducing Peripheral Pseudophakic Dysphotopsia") describes a smooth control surface near the edge of the IOL.

[0015] WO2012023937A1 ("Optics and lOLs for Inhibiting Cell Migration and Reduce Optic Edge Dysphotopsia") describes a serrated edge of the IOL.

[0016] WO2023022972A1 ("Ophthalmic Prosthetic to Treat Negative and Positive Dysphotopsia") describes an optical diaphragm between the IOL and the posterior surface of the iris.

[0017] WO2016132185A1 ("Optical Implantable Member") also describes a protrusion from the peripheral portion of the lens that presumably blocks dysphotopsia.

[0018] US20080269882A1 ("Intraocular Lens with Asymmetric Optics") describes a peripheral extension of the IOL optics.

[0019] US10561491 B2 ("Reduced glare Intraocular lens") describes a sloped edge of the IOL, similar to a chamfer.

[0020] US20220133468A1 ("Intraocular Lenses") describes a peripheral concavity near the edge of the posterior surface of the IOL, introduced into the side of the lens towards the nasal side of the eye.

[0021] W02020083829A1 ("Intraocular Lenses for Reducing Negative Dysphotopsia") describes a posterior portion having a peripheral change in curvature with a sharp posterior edge.

[0022] US20080269883A1 ("Ocular Implant to Correct Dysphotopsia, Glare, Halos and Dark Shadow Type Phenomena") describes haptics with protrusions that hold the IOL very close to the iris.

[0023] IOLs with tilted or textured peripheral portions concentric to the basic optical zone are also described in documents W02022130141A1 ("Intraocular Lens with Rotational Resistance and Negative Dysphotopsia Mitigation") and WO2022229905A1 ("Ophthalmic Lens with Negative Dysphotopsia Mitigation & Glare Reduction").

[0024] EP3954326A1 ("Prosthetic Capsular Device") describes a structure that fills the entire capsule and therefore peripheral rays passing through the device can be diffused.

[0025] US9433498B2 ("Anti-Dysphotopic Intraocular Lens and Method") describes a lens with a peripheral notch that can engage the capsulorhexis and deflect incoming peripheral rays.

[0026] Some of the existing solutions address blocking peripheral light that may bypass the IOL optics, or feature provisions to diffuse light that is refracted near (or at) the edge of the IOL.

[0027] The inventions mentioned require special manufacturing methods and specific (non-standard) testing methods and, in some cases, the implantation of additional elements (apart from the IOL).

[0028] Therefore, infraocular lenses are needed that limit dysphotopsia phenomena and, at the same time, are practical to manufacture and test and simple to surgically implant.

[0029] Summary of the invention

[0030] The object of the invention is to provide an intraocular lens for cataract surgery that overcomes the drawbacks of the prior art.

[0031] The invention features an intraocular lens for cataract surgery comprising an anterior surface and a posterior surface, such that they form a meniscus with the concave anterior surface and the convex posterior surface, in which:

[0032] - the form factor is between -1 and -2

[0033] - the anterior surface has a conic constant between 5 and 50, and

[0034] - the posterior surface has a conic constant between -5 and -2. Accordingly, the present invention introduces a way of incorporating lens curvature into the design of intraocular lenses. This innovative approach aims to minimize or even eliminate the occurrence of entoptic phenomena caused by peripheral light sources.

[0035] By carefully modifying the curvature and shape of the IOL, this technique ensures that the edges of the lens do not interfere with peripheral light, thereby reducing the likelihood of entoptic phenomena. This advance in IOL design promises to reduce visual disturbances in cataract patients and improve their visual experience.

[0036] Brief description of the drawings

[0037] In order that the subject matter of the invention and its advantages may be clearly understood and understood in detail, more particular descriptions and certain embodiments of the invention briefly summarized above are illustrated in the accompanying drawings. These drawings form a part of this specification. It should be noted, however, that the accompanying drawings illustrate preferred embodiments of the invention and therefore should not be construed as limiting its scope.

[0038] Figure 1 shows a cross-section of an eye implanted with an intraocular lens in which a central ray beam is focused on the fovea and a peripheral ray beam is focused on the peripheral retina.

[0039] Figure 2a shows a peripheral ray arriving from an angle A and reflecting off the edge of the IOL located at a distance D behind the iris, causing positive dysphotopsia.

[0040] Figure 2b shows a bundle of peripheral rays reaching the same lens, splitting into two parts and causing a dark zone (ZO) between the two parts (negative dysphotopsia).

[0041] Figure 3a shows a photograph of the phenomenon described in Figure 2b in a real physical model of the human eye in which the split shape of the incoming light can be directly observed. Figure 3b shows a sequence of images of a point source at different eccentricities between 60 and 75 degrees acquired in the retinal plane of a physical model of a pseudophakic eye.

[0042] Figure 4 shows three cross-sections of an eye with intraocular lenses of the same power (20 diopters) but with different form factors implanted at the same depth (IOL apex 1 mm posterior to the iris plane) and indicative angles at which the marginal rays from a 4.5 mm pupil reach the edge of the IOL.

[0043] Figure 5 shows the distance between the posterior surface of the iris and the edge of the IOL (D, as defined in Figure 2a) as a function of the IOL shape factor.

[0044] Figure 6 shows the relative illumination as a function of field angle for an eye implanted with a lens with a form factor of -1.8 (concave meniscus) and the same eye implanted with a biconvex lens (form factor=0).

[0045] Detailed description of the invention

[0046] Figure 3b shows a sequence of images of a point source at different eccentricities between 60 degrees (the top sequence) and 75 degrees (the bottom sequence) acquired in the retinal plane of a physical model of a pseudophakic eye.

[0047] The intraocular lens is biconvex (form factor = 0), the pupillary diameter is 6 mm, and the separation (distance D in Figure 2a) is 1 mm. Under these conditions, at field angles greater than approximately 75 degrees, the light passing through the IOL is eliminated, while the crescent persists and intensifies. This may result in the perception of a dark band or a sharp reduction in illuminance in the far periphery.

[0048] Figure 4 shows three cross-sections of an eye with intraocular lenses of the same power (20 diopters, implanted with different form factors), implanted at the same depth (IOL apex 1 mm behind the iris plane) and indicative angles at which the marginal rays of a 4.5 mm pupil couple to the IOL edge. These angles designate the field angles beyond which dysphotopsias may occur (45 degrees for a lens with a form factor of 2.8; 50 degrees for a lens with a form factor of 0; and 70 degrees for a lens with a form factor of -1.8).

[0049] Figure 5 shows the distance between the posterior surface of the iris and the edge of the IOL (D, as defined in Figure 2a) as a function of the IOL shape factor.

[0050] The nominal depth (4.6 mm) and IOL power (20D) remain constant. It is clear that negative shape factors (in this case, the negative shape factor designates a meniscus with its concave side facing the cornea) result in a significant reduction in the D-spacing.

[0051] Figure 6 shows the relative illumination as a function of field angle for an eye implanted with a lens with a form factor of -1.8 (concave meniscus) and the same eye implanted with a biconvex lens (form factor =0).

[0052] The relative illumination for a human eye with a model lens is provided for reference. The apparent increase in illuminance of the biconvex lens is associated with light not reaching the optic portion of the IOL and falling off at wider field angles, as shown in Figure 2b. This is an undesirable and unnatural optical behavior, as it is followed by an abrupt decrease in illuminance that can be perceived as a "hard stop" of the visual field. The gradual decrease in illuminance with increasing field angles is normal and is associated with the "ellipticity" of the entrance pupil at wider field angles.

[0053] The present invention relates to a novel posterior chamber intraocular lens (IOL) intended for cataract surgery, with a specific focus on mitigating or eliminating dysphotopsia.

[0054] In particular, the invention relates to the application of lens curvature (IOL shape factor transformation) to design IOLs to position the IOL edge out of the path of rays from peripheral objects and thereby reduce or eliminate dysphotopsia. The present invention relates to an intraocular lens for cataract surgery that is manufactured and tested using standard methods and eliminates entoptic phenomena by applying a lens shape factor transformation to position the IOL edge close to the posterior surface of the iris while maintaining safe spacing in the central portion of the pupil.

[0055] The curvature radii mentioned in the following sections are indicative and correspond to a high refractive index IOL material (~1.53). For different materials, the radii can be modified accordingly to achieve the designated dioptric power while maintaining the form factor, as described below.

[0056] In a preferred embodiment, the shape of the IOL is bent to a form factor of approximately -1.8. To achieve this, the posterior surface of the IOL has a radius of curvature between 6.5 mm and 7.5 mm, preferably about 7 mm, while the anterior surface has a radius of curvature of about -25 mm for a power of about 20 diopters. This approach positions the edge of the IOL out of the path of rays from peripheral objects and thereby reduces or eliminates dysphotopsia. For different powers, one or both radii can be varied while maintaining the negative form factor of the lens. In addition, the conic constant of the convex side is adjusted to compensate for spherical aberration of the cornea.

[0057] In another preferred embodiment, the shape of the IOL is bent to a form factor of approximately -1.8. To achieve this, the posterior surface of the IOL has a radius of curvature between 6.5 mm and 7.5 mm, preferably about 7 mm, while the anterior surface has a radius of curvature of about -25 mm for a power of about 20 diopters. This approach positions the edge of the IOL out of the path of rays from peripheral objects and thus reduces or eliminates dysphotopsia. For different powers, one or both radii can be varied while maintaining the negative form factor of the lens. In addition, the conic constant of both surfaces is adjusted in a balanced manner to compensate for spherical aberration of the cornea.In this embodiment, the posterior surface may have a taper constant ranging from about -5 to about -2, and the anterior surface may have a taper constant ranging from about 5 to about 50 for the most common powers. In another preferred embodiment, the shape of the IOL is bent to a form factor of about -1.8. To achieve this, the posterior surface of the IOL has a radius of curvature between 6.5 mm and 7.5 mm, preferably about 7 mm, while the anterior surface has a radius of curvature of about -25 mm for a power of about 20 diopters. This approach positions the edge of the IOL out of the path of rays from peripheral objects and thereby reduces or eliminates dysphotopsia. For different powers, one or both radii may be varied while maintaining the negative form factor of the lens.In addition, the cone constant of both surfaces is adjusted so that the anterior (concave) surface has a substantial amount of negative spherical aberration, achieved by a positive cone constant (e.g., ranging from about 30 to 60) to further increase the curvature at the periphery toward the iris and further reduce the space between the edge of the IOL and the iris. The posterior surface is then adjusted to achieve the required spherical aberration, either to compensate for the spherical aberration of the cornea or to introduce any other deliberate amount of spherical aberration.

[0058] In another preferred embodiment, the shape of the IOL is bent to a form factor of approximately -1.8. To achieve this, the posterior surface of the IOL has a radius of curvature between 6.5 mm and 7.5 mm, preferably about 7 mm, while the anterior surface has a radius of curvature of about -25 mm for a power of about 20 diopters. This approach positions the edge of the IOL out of the path of rays from peripheral objects and thereby reduces or eliminates dysphotopsia. For different powers, one or both radii can be varied while maintaining the negative form factor of the lens. In addition, the conic constant of both surfaces is balanced to introduce a given amount of negative spherical aberration ranging from about -0.3 to about -0.7 micrometers for a 6 mm entrance pupil, as specified in ISO 11979-2 (ISO model 2 eye).

[0059] In another preferred embodiment, the shape of the IOL is bent to a form factor of approximately -1.2. To achieve this, the posterior surface of the IOL has a radius of curvature of approximately 9 mm, while the anterior surface has a radius of curvature of approximately -100 mm for a power of approximately 20 diopters. This approach places the edge of the IOL out of the path of rays from peripheral objects and thereby reduces or eliminates dysphotopsia. For different powers, one or both radii can be varied while maintaining the overall negative form factor of the lens. In addition, the cone constant of both surfaces is adjusted in a balanced manner to compensate for spherical aberration of the cornea. In this embodiment, the posterior surface can have a cone constant ranging from -5 to -2, and the anterior surface can have a cone constant ranging from 5 to 50 for the most common powers.

[0060] In another preferred embodiment, the shape of the IOL is bent with a shape factor ranging from -1 to -2. In addition to bending the shape of the IOL, increasing the diameter of the IOL can further reduce the distance between the edge of the IOL and the posterior iris (provided the shape factor is negative). In this embodiment, the IOL has a negative shape factor less than -1 and between -1.2 and -1.8, and its diameter is increased to 6.5 mm compared to the "industry standard" of 6 mm. In addition, the cone constant of both surfaces is balanced to compensate for spherical aberration of the cornea. In this embodiment, the posterior surface may have a cone constant ranging from -5 to -2 and the anterior surface may have a cone constant ranging from 5 to 50 for the most common powers.

[0061] The value of approximately 7 mm for the radius of curvature of the rear surface (and specifically the range of values ​​between 6.5 and 7.5 mm) is not a random selection equivalent to other similar values. It was carefully chosen following a design process that took the following points into account:

[0062] - This curvature provides substantial lens flex to effectively close the gap between the posterior iris and the lens edge. A flatter curvature (e.g., 9 mm) would still allow a gap of 0.3 mm (typical).

[0063] - This curvature, if kept constant for all IOL powers, will result in gap closure independent of IOL power. In the present invention, the posterior curvature is kept constant across all IOL powers to ensure gap closure at all IOL powers. This could not have been achieved with an even steeper curvature, as it would substantially increase the sagittal height between the apex of the posterior surface and the edge of the IOL to the point where the IOL could press against the posterior capsule and the posterior aspect of the iris.

[0064] - The chosen value is the result of understanding the optics, IOL design, negative dysphotopsia, ocular biomechanics, and surgical requirements, and represents the best design, as it reflects the best balance between manufacturing tolerances (sharp curvatures are more difficult to manufacture accurately) and gap closure effectiveness.

[0065] - This value allows for combination with different anterior surfaces to create a variety of IOL powers without requiring extreme curvatures for the anterior surface. The fact that a single posterior surface is used for all powers is unique to this design. It serves the purpose of bridging the gap to prevent dysphotopsia and also promotes precision, as there is only one "difficult" surface across the entire power range that the manufacturer can optimize (e.g., in a molding process).

Claims

CLAIMS 1 Intraocular lens for cataract surgery, comprising an anterior surface and a posterior surface, such that they form a meniscus with the anterior surface being concave and the posterior surface convex, in which: - the form factor is between -1 and -2 - the anterior surface has a conic constant between 5 and 50, and - the posterior surface has a conic constant between -5 and -2. 2.- Intraocular lens for cataract surgery, according to claim 1, wherein the form factor is between -1.2 and -1.

8. 3.- Intraocular lens for cataract surgery, according to claim 2, wherein: - the form factor is -1 ,8, - the anterior surface has a radius of curvature of -25 mm, and - the posterior surface has a radius of curvature between 6.5 mm and 7.5 mm. 4.- Intraocular lens for cataract surgery, according to claim 3, wherein the posterior surface has a radius of curvature of 7 mm. 5.- Intraocular lens for cataract surgery, according to claim 2, wherein: - the form factor is -1,2, - the anterior surface has a radius of curvature of -100 mm, and - the posterior surface has a radius of curvature of 9 mm. 6.- Intraocular lens for cataract surgery, according to claim 3, 4 or 5, the intraocular lens having a power of 20D. 7.- Intraocular lens for cataract surgery, according to any of the preceding claims, wherein the diameter of the lens is 6.5 mm.

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