Illustrative, non-limiting embodiments of the present invention will be described by way of example with reference to the accompanying drawings, in which a same reference number is used to designate a same or similar components in different figures, and in which:
The haptic arms may be arcuate when viewed from the anterior side (as illustrated in
In
Referring again to
According to some aspects of the invention, a first area 4bant. of the outer surface of at least one of the plates is disposed anteriorly of a centroid of the connection with the at least one plate and at least one of the arms; and a second area 4bpost of the outer surface of the at least one of the plates is disposed posteriorly of the centroid. The first area and the second area are perferably within 200% of one another in magnitude (i.e., the area constituting the first area is less than two-times larger than the area constituting the second area, and the area constituting the second area is less than two-times the area constituting the first area). In some embodiments, the first and second areas are within 150% of one another. In other embodiments, the first and second areas are within 125% of one another.
In some embodiments, a midpoint of outer surface 4aO of at least one of said plates, and a midpoint of the connection are disposed substantially on a common plane that is perpendicular to the optical axis. A midpoint is the middle of a surface as measured along the direction of optical axis OA. It is to be appreciated that, while in the illustrated embodiment the midpoint is coincident with the centroid, in other embodiments they will not be coincident.
In some embodiments, at least one of the plates is configured and arranged such that there is substantially no moment of a haptic arm that would produce posterior translation of the optic in response to a force applied to the outer surface of the haptic. In some of the embodiments, all of the haptics are so configured. As discussed above, a problem with the prior lenses is the existence of moment that causes a translation force in a posterior direction when the lens is placed in the eye. Such a force resists accommodative (i.e., anterior) movement of the lens. While in some embodiments of the present invention provide no moment to the optic when force is applied to the outer surfaces of the plates by a capsular bag, in other embodiments, the moment is substantially reduced from the prior, but is not completely absent.
Also, similar to the lens discussed above with reference to
In some embodiments, a midpoint of the outer surface of at least one of said plates, and a midpoint of the connection are disposed substantially on a common plane that is perpendicular to the optical axis. In some embodiments, at least one of the plates is configured and arranged such that there is substantially no moment of a haptic arm that would produce posterior translation of the optic.
Three tab-shaped connective segments 15 that are disposed 120° from each other are arranged and protrude outward in the edge 10 region of the optic 1′. The connective segments 15 are comparatively narrow and exhibit a width B that corresponds to a central angle b of approximately 5°≦b≦20°. In some embodiments b=10′.
In the illustrated embodiment, each connective segment 15 comprises a hinge 16. Hinges 16 exhibit corresponding pivot axes 17 which is disposed substantially in the center of the hinge 16 and are disposed substantially along middle plane P1′. On the posterior side of the lens, the connective segments 15 each include a groove-shaped depression that forms the hinge. The connective segments 15 exhibit a radial length L1 that in some embodiments is equal to approximately the width B.
Haptic arms 2a′, 2b′, and 2c′ are disposed at the outer ends of the connective segments 15. Each arm is coupled to the optic along its length L′. The arms 2a′, 2b′, and 2c′ are convexly arched about the optical axis OA, and in their middle section run in an approximately circular arc, such that the distance between the edge 10 and the arms 2a′, 2b′, and 2c′ is approximately constant. In the illustrated embodiment, the arms 2a′, 2b′, and 2c′ exhibit a width C that is approximately equal to width B. Both outer ends 18 of each arm 2a′, 2b′, and 2c′ are connected with a plate 4a′, 4b′, and 4c′. In some embodiments, ends 18 belonging to a given one of the arms 2a′, 2b′, and 2c′ subtend an angle d with reference to the axis OA of about 70°≦d≦105°. In the illustrated embodiment d≈90°.
Each plate has an outer surface arranged to contact the capsular bag. Each plate is coupled to at least two of the haptic arms, the coupling with each arm occurring at a connection Cd, Ce, and Cf. For example, the adjacent ends 18 of arms 2b′ and 2c′ are connected with plate 4c′. The arms 2a′, 2b′, and 2c′ and the plates 4a′, 4b′, and 4c′ roughly comprise an equilateral triangle in which the vertices of the triangle are formed by the plates 4a′, 4b′, and 4c′. It will be appreciated that, in some embodiments, due to the arcuate shape of the haptic arms and plates the arms and plates may have a substantially circular shape. The haptic arms and plates, in combination, being arranged to form a closed figure surrounding the optic. Plates 4a′, 4b′, and 4c′ each exhibit a central angle e with reference to optical axis OA. In some embodiments, 45°≦e≦75°. In the illustrated embodiments, e≈60°.
Plates 4a′, 4b′, and 4c′ extend in an angular direction over the ends 18 of each of the arms. An arm 2a′, 2b′, and 2c′, which comprises a largely tangentially running portion and protruding connective segment 19. The connective segment extends in a radial direction in the region of the ends 18 of the arms. The thickness T of the plates is typically 0.3-0.7 mm.
In some embodiments, the connective segment at which the haptic arms couple to the plates each include a hinge 20 that exhibits a pivot axis 21 which is parallel to the middle plane P1′ and displaced from the plane. Hinge 20 enables relative pivoting of an arm and corresponding plate. Although the present embodiment is described as having hinges 16 and 20, it is possible to omit one or both of the hinges on a given arm. In embodiments in which both hinges are omitted, each arm 2a′, 2b′, or 2c′ may have a largely constant thickness to transition into the plate 4a′, 4b′, or 4c′ (i.e., the haptic arms are formed without either one or both of locally defined external hinge 20 or 16). In such embodiments, the segment of each arm between the connective segment 15 and each plate 4a′, 4b′, or 4c′ assumes the function of the hinges 16 and 20. This result is achieved by selecting an arm thickness that provides continuous deformation along the length of the arm in response to a radial force applied to the outer surface of a corresponding plate. Accommodative movement is thereby achieved.
Each plate 4a′, 4b′, and 4c′ exhibits a cylindrical interior surface 23, which faces toward the axis OA. The plates 4a′, 4b′, and 4c′ exhibit a toroidal exterior surface 22. The connective segments 15, the arms 2a′, 2b′, and 2c′, and the plates 4a′, 4b′, and 4c′ together comprise the haptic 2′, which supports the optic 1′ against the equatorial region of the capsular sac. Typically, the plates extend at least partially beyond the haptic arm in both the anterior and the posterior directions. However, the invention is not so limited.
In an unstressed condition, plates 4a′, 4b′, and 4c′ are disposed posteriorly of middle plane P1′. Angle f is defined as the angle between the middle plane P1′ and a line Q through the middle of hinges 16 and the middle of hinges 20, where 2°≦f≦25°, and preferably f≈5° and corresponds, in other words, to a slight biasing of the lens 80 in the anterior direction.
Similar to the lens discussed above with reference to
Three openings 27 are defined by two adjacent arms (e.g., 2a′ and 2c′). In some embodiments, a part of edge 10 of optic 1′, as well as the middle section of the interior surface 23 of a plate such as the plate 4a′. A protrusion 28 that is radially off-center may be provided in the region of its edge 10. The protrusions enable the recognition an anterior side and the posterior side of the lens 80. If the lens 80 is placed correctly in the capsular sac, each protrusion 28 in the corresponding opening 27 will be located in the right half of the opening 27 from the perspective of the physician. If the placement is in the incorrect orientation, each protrusion 28 will be located in the left half of the corresponding opening 27.
Lens 80 may, instead of three plates, contain a larger number, for example, four, five, six, seven or more plates with a corresponding number of arms. As described above, in each case, the arms and plates, in combination, are arranged to form a closed figure surrounding an optic.
The implantation and accommodative behavior of the lens 80 will now be described in brief. After placing the circular capsulorhexis and removing the natural lens from the capsular sac in the eye of a patient, the lens 80 is introduced into the capsular sac through a small slit in the cornea so that the anterior direction 11 of the lens 80 is oriented toward the front of the eye, and the posterior direction 14 is oriented toward the rear in the direction of the retina. The optical axis OA of the lens and visual axis VA of the eye are substantially aligned.
The plates 4a′, 4b′, and 4c′ are positioned to bear against the inside of the capsular sac in its equatorial region. The optic 1′ is arched in the anterior direction 11 in the sense that the angulation angle f is greater than 0° so that the exterior pivot axes 21 lie behind the pivot axes 17. This state corresponds to distance vision in the human eye. Upon contraction of the patient's ciliary muscles a radial force is exerted inward on the plates 4a′, 4b′, and 4c′. This causes a displacement of the optic 1′ in the anterior direction 11, i.e., the lens is more pronouncedly biased toward the front. Such displacement provides near vision for the patient. In the accommodative process, the optic 1′ remains largely unchanged, such that its optical properties remain unchanged and accommodation is achieved through displacement of the lens.
It will be appreciated that, while implantation and accommodation was discussed with reference to lens 80, the implantation and accommodation of lenses 40 and 60 (discussed above) will be substantially similar.
Lenses according to aspects of the present invention are preferably made from materials that are reversibly deformable. This means that after deformation, e.g., by pressure exerted on the haptics, the material returns to its original state once the external pressure is removed. For example, lenses may be manufactured of transparent silicone or acrylic. In some instances, pHEMA, poly-hydroxyethyl-methacrylate is used.
The lens may be produced, for example, by molding or machining or a combination of both. In some instances in which the lens is machined, the material is preferably kept in a rigid state during processing. The product resulting from the machining is then placed in an aqueous saline solution, whereby the lens absorbs water and becomes elastic. Lenses may be manufactured as a single integrated unit with the lens including an optic, haptics and plates; however, the various parts may be individually manufactured and subsequently assembled.
Having thus described the inventive concepts and a number of exemplary embodiments, it will be apparent to those skilled in the art that the invention may be implemented in various ways, and that modifications and improvements will readily occur to such persons. Thus, the embodiments are not intended to be limiting and presented by way of example only. The invention is limited only as required by the following claims and equivalents thereto.