Posterior chamber intraocular lens

Abstract

The present invention relates to a posterior chamber intraocular lens (IOL), comprising: an optic consisting of an effective optical area and an effective optical area edge; at least two haptics connected to the optic, wherein a posterior surface of the effective optical area is a convex surface, and a basic spherical surface thereof has a radius of curvature in a range of 6.6 mm-80.0 mm. The effective optical area of the posterior chamber IOL adopts a design with the posterior surface obviously convex, which reduces the distance between the posterior surface of the effective optical area of the IOL and the posterior capsule, improves the stability of a spatial position of the IOL in a capsule bag, and reduces an incidence rate of posterior capsule opacification (PCO) after implantation of the IOL; since the effective optical area anterior surface is relatively flat, the IOL haptics will not be tightly pressed on the effective optical area anterior surface upon folding, the haptics are more easily unfolded after implantation into the eye and the support haptics are not mutually adhered to the effective optical area, and meanwhile the IOL imaging quality can be improved and/or the visual quality of the astigmatism sufferer is enhanced.

Claims

1. A posterior chamber intraocular lens (IOL) comprising: an optic consisting of an effective optical area and an effective optical area edge disposed around the effective optical area; at least two haptics symmetrically connected to the optic around a circumferential direction of the optic, the at least two haptics selected from the group consisting of L-shaped haptics and C-shaped haptics, wherein: an anterior optical surface of the effective optical area is a convex surface, and a basic spherical surface thereof has a radius of curvature in a range of 14.4 mm to 74.0 mm, a posterior optical surface of the effective optical area is a convex aspherical surface, and a basic spherical surface thereof has a radius of curvature in a range of 7.2 mm to 15.3 mm, and the radius of curvature of the basic spherical surface of the posterior optical surface of the effective optical area is smaller than the radius of curvature of the anterior optical surface of the effective optical area, wherein the radius of curvature of the basic spherical surface of the posterior optical surface of the effective optical area is 17.8%-60.0% of the radius of curvature of the anterior optical surface of the effective optical area, wherein the posterior chamber intraocular lens comprises hydrophobic acrylate having a refractive index of 1.47-1.55, wherein roots of the haptics are directly connected to the effective optical area edge of the optic, wherein the effective optical area edge further comprises a sharp bend dimensioned and configured to press tightly against the posterior capsule membrane of the eye, wherein the convex aspherical surface of the posterior optical surface comprises a high order aspherical surface design in order to correct spherical aberration and high order aberrations, and to further improve the imaging quality of the basic spherical surface, and wherein substantially the entirety of the posterior optical surface of the effective optical area is dimensioned and configured to be in direct close contact with the posterior capsule membrane of the eye to improve the stability of a spatial position of the IOL in the capsule bag and also to reduce incidence rate of posterior capsule opacification (PCO) after implantation of the IOL into the human eye.

2. The posterior chamber IOL according to claim 1, wherein the radius of curvature of the basic spherical surface of the posterior optical surface of the effective optical area is 20.0%-45.6% of the radius of curvature of the anterior optical surface of the effective optical area.

3. The posterior chamber IOL according to claim 1, wherein a longitudinal center line of the haptic roots is at a haptic angle in a range of 0-7 relative to a longitudinal center line of the optic.

4. The posterior chamber IOL according to claim 1, wherein the surface shape of an the anterior optical surface of the effective optical area comprises one of spherical surface, aspherical surface, toric surface, multi-focal surface of multi-area refraction design and multi-focal surface of multi-area diffraction design.

Description

BRIEF DESCRIPTION OF PREFERRED EMBODIMENTS

(1) The features and advantages will be made more apparent according to the following figures and description, wherein:

(2) FIG. 1 schematically illustrates a basic composition of a human eye refractive system;

(3) FIG. 2 schematically illustrates a graph showing the distribution of spherical aberration magnitude (L.sub.0) of intraocular lenses in the prior art having different surfaces;

(4) FIG. 3 schematically illustrates a perspective view of a one-piece posterior chamber intraocular lens according to an embodiment of the present invention as viewed from above an anterior surface of the intraocular lens, wherein haptics are unfolded and not yet folded onto the anterior surface of the optics of the intraocular lens;

(5) FIG. 4 schematically illustrates a perspective view of a one-piece posterior chamber intraocular lens according to an embodiment of the present invention as viewed above a posterior surface of the intraocular lens, wherein haptics are unfolded and not yet folded onto the anterior surface of the optics of the intraocular lens;

(6) FIG. 5 illustrates a cross-sectional view of a one-piece e posterior chamber intraocular lens according to an embodiment of the present invention, wherein haptics are already folded onto the anterior surface of the optics of the intraocular lens;

(7) FIG. 6 illustrates a schematic view of interaction relationship between an effective optical area posterior surface and a posterior capsule of a posterior chamber intraocular lens in the prior art implanted into a human eye when a capsulate bag is in a retracted state;

(8) FIG. 7 illustrates a schematic view of interaction relationship between an effective optical area posterior surface and a posterior capsule of a one-piece posterior chamber intraocular lens according to the present invention implanted into a human eye when a capsulate bag is in a retracted state;

(9) FIG. 8 schematically illustrates interaction relationship between an effective optical area posterior surface and a posterior capsule of a posterior chamber intraocular lens in the prior art as shown in circle G of FIG. 6;

(10) FIG. 9 schematically illustrates interaction relationship between an effective optical area posterior surface and a posterior capsule of a one-piece posterior chamber intraocular lens in the present invention as shown in circle H of FIG. 7;

(11) FIG. 10 schematically illustrates, in the form of a cross sectional view, a situation in which haptics of one-piece posterior chamber intraocular lens in the prior art are folded onto the effective optical area anterior surface before the intraocular lens is implanted into a human eye;

(12) FIG. 11 schematically illustrates, in the form of a cross sectional view, a situation in which haptics of one-piece posterior chamber intraocular lens in the present invention are folded onto the effective optical area anterior surface before the intraocular lens is implanted into a human eye;

(13) FIG. 12 schematically illustrates the difference between an effective optical area surface of a higher order aspherical intraocular lens according to an embodiment of the present invention and a corresponding spherical surface;

(14) FIG. 13 schematically illustrates longitudinal aberration graphs of IOLs having three different posterior surface designs (namely, the posterior surface being an obviously convex spherical surface, a flat spherical surface and an obviously convex aspherical surface design) with a 5 mm light transmission aperture and 20D diopter as obtained through ZEMAX simulation in an eye model;

(15) FIG. 14A is an aberration distribution diagram when a spherical surface IOL, a single Q-value aspherical surface IOL and a higher order aspherical surface IOL are at a central position (with a pupil diameter 5.0 mm);

(16) FIG. 14B is an aberration distribution diagram when a spherical surface IOL, a single Q-value aspherical surface IOL and a higher order aspherical surface IOL off-center 1 mm (with a pupil diameter 5.0 mm);

(17) FIG. 14C is an aberration distribution diagram when a spherical surface IOL, a single Q-value aspherical surface IOL and a higher order aspherical surface IOL are inclined 7 (with a pupil diameter 5.0 mm);

(18) FIG. 15 is a modulation transfer function (MTF) graph as actually measured in a human eye model with a cornea aberration when a spherical surface IOL, a single Q-value aspherical surface IOL and a higher order aspherical surface IOL with a small radius of curvature at a posterior surface are at a central position (with a pupil diameter 5.0 mm);

(19) FIG. 16 is a MTF graph as actually measured in a human eye model with a cornea aberration when a spherical surface IOL, a single Q-value aspherical surface IOL and a higher order aspherical surface IOL with a small radius of curvature at a posterior surface are off-centered 1 mm (with a pupil diameter 5.0 mm);

(20) FIG. 17 is a MTF graph as actually measured in a human eye model with a cornea aberration when a spherical surface IOL, a single Q-value aspherical surface IOL and a higher order aspherical surface IOL with a small radius of curvature at a posterior surface are off-centered 0.5 mm and inclined 5 (with a pupil diameter 5.0 mm);

(21) FIG. 18 schematically illustrates the principle of forming a toric surface;

(22) FIG. 19A and FIG. 19B are respectively a point spread function contrast diagram after an ordinary aspherical surface intraocular lens and Toric intraocular lens of the present invention are respectively implanted into a human eye with corneal astigmatism obtained through simulation by adopting ZEMAX, wherein the human eye model has 2.9D corneal astigmatism;

(23) FIG. 20A and FIG. 20B are respectively an MTF contrast diagram after an ordinary aspherical intraocular lens and Toric intraocular lens of the present invention are respectively implanted into a human eye with corneal astigmatism obtained through simulation by adopting ZEMAX, wherein the human eye model has 2.9D corneal astigmatism;

(24) FIG. 21 schematically illustrates a perspective view of a one-piece posterior chamber intraocular lens according to another embodiment of the present invention, wherein haptics are unfolded and not yet folded onto the anterior surface of the optics of the intraocular lens, the view particularly including a cross section of a transition connection section between the optics and haptics;

(25) FIG. 22 particularly and illustratively shows the transition connection section between the optics and the haptics in a one-piece posterior chamber intraocular lens as shown in the cross section of FIG. 21;

(26) FIG. 23 schematically shows a positional relationship between an intraocular lens axial direction and a maximum refractive power direction of the human cornea when the Toric intraocular lens is implanted into a human eye;

(27) FIG. 24 schematically shows a MTF contrast diagram of the intraocular lens (preferred embodiment) of the present invention with a spherical surface and a toric surface being respectively located on both sides and a prior-art intraocular lens (comparative example) with the aspherical surface and the toric surface being located on the same side, at a spatial frequency of 0-100 lp/mm in a human eye model with astigmatism and a pupil diameter 3.0 mm;

(28) FIG. 25 schematically shows a wave front chart of a surface design of an intraocular lens of the present invention at an image surface in a human eye model (with an aspherical surface and a toric surface being respectively located on both sides); and

(29) FIG. 26 schematically a wave front chart of a surface design in the prior art in a human eye model with an aspherical surface and a toric surface being combined on one surface.

(30) The same reference signs used in the figures of the present application denote identical or similar elements.

LISTING OF PARTS DENOTED BY REFERENCE SIGNS

(31) 1 posterior chamber intraocular lens 2 optic 3 effective optical area 4 effective optical area edge 5 haptics 6 effective optical area anterior surface 7 effective optical area posterior surface 8 longitudinal central plane of optics of the intraocular lens 8-8 longitudinal center line of optics of the intraocular lens 9 posterior capsule 10 gap 11 cornea 12 capsule bag 13 fold gap 14 sharp bend 15 transition connection section 15-15 longitudinal center line of the transition connection section 16 haptic root 16-16 longitudinal center line of the haptic root 18 Toric IOL axial mark A an intersection point of the longitudinal center line of the IOL optics and the longitudinal center line of the transition connection section haptic angle an inclination angle of the transition connection section D-D ocular axis direction E-E maximum refractive power direction of human cornea d-d rotation formation axis of a toric surface O effective optical area (anterior or posterior) surface apex R rotation radius r radius of curvature

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

(32) The following specific embodiments are only used to further illustrate the present invention, but the present invention is not limited to the following specific embodiments. Any variations on the basis of these embodiments all fall within the scope of protection of the present invention so long as they conform to the principle, spirit and scope of the present invention.

(33) (I) Backwardly Convex Design of the IOL Effective Optical Area

(34) Further improvement of stability of the implanted IOL in the human eye capsule bag and reduction of the probability of posterior capsule opacification are factors to be considered first in design of the surface shape of the IOL effective optical area of the present invention.

(35) FIG. 3 is a perspective view of a one-piece posterior chamber intraocular lens 1 according to an embodiment of the present invention as viewed from above an anterior surface of the intraocular lens. FIG. 4 illustrates a perspective view of a one-piece posterior chamber intraocular lens according to an embodiment of the present invention as viewed from above a posterior surface of the intraocular lens. As shown in FIGS. 3 and 4, the posterior chamber IOL 1 comprises an optic 2 consisting of an effective optical area 3 and an effective optical area edge 4; and two support haptics 5 integrally formed with the optic 2. The support haptics 5 are directly connected to the effective optical area edge 4 of the optic. Certainly, those skilled in the art may appreciate that the number of haptics 5 may be more than two, preferably less than six. The haptics 5 are symmetrically disposed on the effective optical area edge 4 around a circumferential direction of the optic 2 and connected to the anterior surface of the optic. Certainly, those skilled in the art may appreciate that the haptics 5 are symmetrically disposed on the effective optical area edge 4 around a circumferential direction of the optic 2 and integrally connected to the side of the optic. As shown in FIG. 3 and FIG. 4, a posterior surface 7 of the effective optical area 3 is convex and an anterior surface 6 of the effective optical area 3 is convex. Those skilled in the art may appreciate that a surface shape of the posterior surface 7 of the effective optical area 3 may comprise one of spherical shape, aspherical surface, toric surface, multi-focal surface of multi-area refraction design and multi-focal surface of multi-area diffraction design; a surface shape of the anterior surface 6 of the effective optical area 3 comprises one of spherical shape, aspherical surface, toric surface, multi-focal surface of multi-area refraction design and multi-focal surface of multi-area diffraction design. As shown in FIG. 3 and FIG. 4, the haptics 5 of the one-piece posterior chamber IOL 1 are in a unfolded state and not yet folded onto the anterior surface of the IOL optic 2.

(36) FIG. 5 illustrates a cross-sectional view of a one-piece posterior chamber intraocular lens 1 according to an embodiment of the present invention, wherein haptics 5 are already folded onto the anterior surface of the optics 2 of the intraocular lens. As can be clearly seen from the figure, the effective optical area posterior surface 7 of the posterior chamber IOL 1 is more obviously convex than the effective optical area anterior surface 6 of the posterior chamber IOL 1. Particularly regarding the surface design of the posterior chamber IOL 1 with an obviously backwardly convex effective optical area posterior surface, the L-shaped or C-shaped haptics of the present invention can form a three-point stabilizing structure with the obviously backwardly convex posterior surface of the posterior chamber IOL 1 of the present invention, so as to improve stability of a position of the intraocular lens in a capsule bag and facilitate reduction of an incidence rate of posterior capsule opacification (PCO) after implantation of the intraocular lens.

(37) FIG. 6 illustrates a schematic view of interaction relationship between an effective optical area posterior surface 7 and a posterior capsule 9 of a posterior chamber intraocular lens 1 in the prior art implanted into a human eye when a capsulate bag is in a retracted state. The surface shape of the effective optical area of the prior-art posterior chamber IOL 1 shown in FIG. 6 is a slightly convex surface shape (the effective optical area anterior surface is convex and the effective optical area posterior surface is slightly convex). After the prior-art posterior chamber IOL 1 shown in FIG. 6 is implanted into the human eye, the posterior chamber IOL 1 is maintained at a relative position in the human eye posterior chamber capsule bag by virtue of interaction between the support haptics 5 and the capsule bag 12. The retraction and expansion of the capsule bag act upon the support haptics 5, so that the IOL connected to the haptics is pressed or stretched to move forward and rearward along an ocular axis direction D-D. Since the effective optical area posterior surface of the prior-art posterior chamber IOL 1 is slightly convex (or approximately flat), when the prior-art posterior chamber IOL 1 already implanted into the human eye is pressed or stretched in the posterior chamber, a gap 10 more or less exits between the effective optical area posterior surface and the posterior capsule membrane 9; upon retraction of the capsule bag, the prior-art posterior chamber IOL, under action of a retraction force P, may move in a larger space scope S, whereby the close contact between the effective optical area posterior surface 7 and the posterior capsule membrane 9 is caused unstable, and the residual lens epithelial cells after cataract surgery multiply and easily migrate to between the prior-art IOL effective optical area posterior surface and posterior capsule through the gap 10 between the effective optical area posterior surface and the human eye posterior capsule membrane 9, whereby posterior capsule opacification (PCO) phenomenon is likely to occur.

(38) FIG. 7 illustrates a schematic view of interaction relationship between an effective optical area posterior surface 7 and a posterior capsule membrane 9 of a posterior chamber intraocular lens 1 according to the present invention implanted into a human eye when a capsulate bag is in a retracted state. As compared with the convexity of the effective optical area posterior surface of the prior-art posterior chamber IOL 1 as shown in FIG. 6, the effective optical area posterior surface of the posterior chamber IOL 1 of the present invention of FIG. 7 is more obviously outwardly convex. After the posterior chamber IOL 1 shown in FIG. 7 is implanted into the human eye, the posterior chamber IOL 1 is maintained at a relative position in the human eye posterior chamber capsule bag by virtue of interaction between the support haptics 5 and the capsule bag. The retraction and expansion of the capsule bag act upon the support haptics 5, so that the IOL 1 connected to the haptics 5 is pressed or stretched to move forward and rearward along an ocular axis direction D-D. As compared with the commonly-seen the prior-art IOL, there is a smaller gap between the effective optical area posterior surface and the posterior capsule of the IOL with an obviously rearwardly convex surface shape of the present invention shown in FIG. 7, and upon retraction of the capsule bag, the posterior chamber IOL, under action of a retraction force P, may move in a relatively smaller space scope S, whereby stability of the position of the lens in the capsule bag is improved. Specifically, since the effective optical area posterior surface of the IOL 1 of the present invention as shown in FIG. 7 is obviously outwardly convex, when the IOL 1 is implanted into the human eye and pressed or stretched in the posterior chamber, the gap 10 between the effective optical area posterior surface of the posterior chamber IOL 1 of the present invention and the human eye posterior capsule membrane 9 is minimized so that the effective optical area posterior surface can more closely contact with the human eye capsule membrane 9, thereby making the close contact between the effective optical area posterior surface 7 and the posterior capsule membrane 9 stabler, and prevent the residual lens epithelial cells after cataract surgery from multiplying and from migrating to between the prior-art IOL effective optical area posterior surface and posterior capsule through the gap 10 between the effective optical area posterior surface and the human eye posterior capsule membrane 9. As can be seen from the above, the obviously convex posterior surface of the effective optical area of the IOL may reduce the gap between the posterior capsule and the effective optical area and reduce an incidence rate of posterior capsule opacification (PCO) after implantation of the IOL.

(39) FIG. 8 illustrates interaction relationship between an effective optical area posterior surface and a posterior capsule membrane of a posterior chamber intraocular lens in the prior art as shown in circle G of FIG. 6. FIG. 9 illustrates interaction relationship between an effective optical area posterior surface and a posterior capsule membrane of a one-piece posterior chamber intraocular lens in the present invention as shown in circle H of FIG. 7. A premise for the right-angle design adopted by the prior-art IOL effective optical area edge 4 to prevent growth of the PCO is that the IOL edge right-angle side can press tightly against the posterior capsule membrane 9 and thereby better hinders the migrational flow of the lens epithelial cells. A comparison of FIG. 8 and FIG. 9 shows: as compared with the prior-art posterior chamber IOL, the effective optical area of posterior surface of the posterior chamber IOL of the present invention can more closely contact with the posterior capsule membrane, whereby the obviously convex surface shape design of the posterior surface of the posterior chamber IOL effective optical area of the present invention can give full play to the advantages of the right-angle edge effect of the IOL optical effective area edge.

(40) Upon implantation of the IOL, the IOL needs to be placed in a guide-in head for surgery, and a haptic-folding act is usually performed. FIG. 10 illustrates, in the form of a cross sectional view, a situation in which haptics of one-piece posterior chamber intraocular lens in the prior art are folded onto the effective optical area anterior surface before the intraocular lens is implanted into a human eye. FIG. 11 illustrates, in the form of a cross sectional view, a situation in which haptics of one-piece posterior chamber intraocular lens in the present invention are folded onto the effective optical area anterior surface before the intraocular lens is implanted into a human eye. Before implantation, the haptics of a one-piece IOL generally need to be folded onto the anterior surface 6 of the IOL optic so as to prevent a thimble of an implanter from damaging the haptics 5 before advancing the IOL. A comparison of FIG. 10 and FIG. 11 makes the following noticeable: if the anterior surface of the IOL effective optical area is too convex, the haptics gets close to the anterior surface of the IOL effective optical area so that a fold space 13 is smaller. When the IOL is pushed out of the guide-in head, the haptics 5 cannot be easily unfolded. The obviously convex surface shape design of the effective optical area posterior surface 7 of the one-piece posterior chamber IOL 1 of the present invention is such that the anterior surface 6 of the optic may be relatively flatter so as to reduce the contact area and action force between the folded haptics and the anterior surface 6 of the optic to make the fold gap 13 larger. Therefore, the obviously convex surface shape design of the effective optical area posterior surface 7 of the one-piece posterior chamber IOL 1 of the present invention is further such that after the one-piece posterior chamber IOL 1 of the present invention is implanted into the human eye, the haptics folded onto the anterior surface 6 of the optic of the one-piece posterior chamber IOL 1 of the present invention can be more easily unfolded and thereby reduces the risk of failure to smoothly unfold due to mutual adhesion of the support haptics and the IOL effective optical areal.

(41) FIG. 21 illustrates a perspective view of a one-piece posterior chamber intraocular lens according to another embodiment of the present invention, wherein haptics are unfolded and not yet folded onto the anterior surface of the effective optical lens of the intraocular lens, the view particularly including a cross section of a transition connection section between the optics and haptics. FIG. 22 specifically and illustratively shows the transition connection section between the optics and the haptics in a one-piece posterior chamber intraocular lens as shown in the cross section of FIG. 21. As shown in FIG. 21 and FIG. 22, the posterior chamber IOL 1 according to another embodiment of the present invention comprises: an optic 2 consisting of an effective optical area 3 and an effective optical area edge 4, two support haptics 5 integrally formed with the optic 2, and a transition connection section 15 between the optic 2 and the support haptics 5. The support haptics 5 are directly connected to the effective optical area edge 4 of the optic 2 via the transition connection section 15. The transition connection section 15 is substantially conical or cylindrical and is machined during preparation of the IOL. Alternatively, the effective optical area edge 4 may further comprise a sharp bend 14 such as a right-angle side configuration. One end of the transition connection section 15 is directly connected to the effective optical area edge 4 of the optic 2, and the other end of the transition connection section 15 is directly connected to haptic roots 16 of the support haptics 5. The haptic roots 16 are located at an end opposite to a free end of the support haptics 5 and substantially extend straight. A longitudinal center line 16-16 of the haptic roots 16 is inclined relative to a longitudinal center line 8-8 of the optic 2 of the posterior chamber IOL 1, and is at a haptic angle in a range of 0-7. A longitudinal center line 15-15 of the transition connection section 15 is inclined relative to the longitudinal center line 8-8 of the optic 2 of the posterior chamber IOL 1, and is at a transition connection section inclination angle in a range of 10-45. The transition connection section inclination angle is greater than the haptic shaping angle . The sharp bend 14 facilitates forming a mechanical barrier on the posterior capsule membrane 9, interrupting migrational flow of the epithelial cells and meanwhile enhancing connection strength of the optic and the haptics. Besides, when the IOL 1 connected to the support haptics 5 is pressed or stretched due to retraction and expansion of the capsule bag, due to existence of the haptic shaping angle (namely, a design angle of haptics), a radial force received by the haptics 5 is divided into a component force in the ocular axis direction enabling the optical surface to move towards the posterior capsule and a component force perpendicular to the ocular axis direction enabling the surface shape of the effective optical area to change, so as to ensure permanent close contact between the effective optical area posterior surface 7 and the posterior capsule 9. This close contact type structural design substantially reduces occurrence probability of PCO. The structural configuration including the haptic shaping angle , the transition connection section 15 and (optionally) the sharp bend 14 is combined with the obviously rearwardly convex effective optical area posterior surface 7 of the posterior chamber IOL 1 of the present invention so that the obviously rearwardly convex effective optical area posterior surface 7 can be allowed to more closely contact with the posterior capsule membrane 9 such that the posterior chamber IOL 1 of the present invention can be more firmly positioned in the posterior capsule 9, thereby better blocking growth of PCO. Certainly, those skilled in the art may appreciate that the number of haptics 5 may be more than two, preferably less than six. The haptics 5 are symmetrically disposed on the effective optical area edge 4 around a circumferential direction of the optic 2 and connected to the anterior surface of the optic. Certainly, those skilled in the art may appreciate that the haptics 5 are symmetrically disposed on the effective optical area edge 4 around a circumferential direction of the optic 2 and integrally connected to the side of the optic.

(42) In addition, those skilled in the art can further appreciate that the posterior chamber IOL with obviously convex effective optical area posterior surface may be the one-piece IOL as described in the above embodiments, or three-piece IOL. Regarding the three-piece IOL, surface shape design features of the effective optical area thereof are similar to those of the one-piece IOL as described in the above embodiments and will not be detailed here. As compared with the posterior chamber IOL in the prior art, the three-piece e posterior chamber IOL according to the present invention has the obviously convex effective optical area posterior surface, which can reduce the gap between the posterior capsule and the effective optical area after implantation, reduce the opportunity for the epithelial cells to migrate to between the three-piece IOL posterior surface and posterior capsule and thereby reduce incidence rate of PCO after implantation of the three-piece posterior chamber IOL. Besides, the obviously convex effective optical area posterior surface of the three-piece posterior chamber IOL according to the present invention can also more closely contact with the posterior capsule membrane so that the IOL can be more stably positioned in the posterior capsule and thereby advantages of the right-angle edge effect of the IOL effective optical area edge are reflected better.

(43) (II) The Surface Shape Design of the IOL Effective Optical Area

(44) Table 2 below lists an example of surface shape design of the effective optical area of the posterior chamber IOL of the present invention fabricated from different materials.

(45) When the effective optical area surface of the posterior chamber IOL of the present invention has a spherical surface shape, the surface shape of the effective optical area surface of the posterior chamber IOL of the present invention can be directly represented by using the radii of curvature of the IOL anterior and posterior effective optical area surfaces.

(46) When the effective optical area surface of the posterior chamber IOL of the present invention further adopts high order aspherical surface design and/or toric surface design, this means adding the high order aspherical surface design and/or toric surface design on the basic spherical surface of the effective optical area of the posterior chamber IOL adopting different materials as listed in the following Table 2 in the present invention. At this time, the radius of curvature of the anterior surface and the radius of curvature of the posterior surface as listed in the following Table 2 are respectively the radius of curvature of the basic spherical surface of the effective optical area anterior surface of the posterior chamber IOL and the radius of curvature of the basic spherical surface of the effective optical area posterior surface of the posterior chamber IOL. An aspherical surface design is intended to further improve the imaging quality of the basic spherical surface, and the toric surface design (Toric) is intended to additionally correct human eye astigmatism and improve visual quality of astigmatism sufferer.

(47) For the sake of convenient and consistent depictions, the spherical surfaces involved by the posterior chamber IOL of the present invention in the above two situations are both called basic spherical surface in further explanations and analysis of data in the following Table 2.

(48) The refractive indices of examples of the following materials adopted by the posterior chamber IOL of the present invention all are between 1.45 and 1.56. As known by those skilled in the art, a conventional preparation method may be adopted according to needs to enable the prepared materials to have any refractive index between 1.45 and 1.56. Besides, a thickness at a center of the effective optical area of the posterior chamber IOL of the present invention is in a range of 0.3 mm-1.2 mm, and a thickness of the effective optical area edge is in a range of 0.3 mm-0.6 mm. A thickness at a center of the effective optical area refers to a thickness at the thickest position at the center of the effective optical area of the posterior chamber IOL of the present invention; a thickness of the effective optical area edge refers to a thickness measured at a transition position between the effective optical area and the effective optical area edge of the posterior chamber IOL of the present invention. As publicly known by those skilled in the art, the magnitude of the thickness at a center of the effective optical area of the posterior chamber IOL of the present invention and the magnitude of the thickness of the effective optical area edge of the posterior chamber IOL of the present invention depend on the utilized material and the achieved diopter. These IOLs of the present invention having the surface shape designs of the effective optical area surface as listed in Table 2 all can achieve a diopter of 5.0D-36.0D. At present, the most frequently and clinically used IOL is an IOL having a diopter approximate to 20D.

(49) TABLE-US-00002 TABLE 2 Example of Surface Shape Design of Effective Optical Area of Posterior Chamber IOL of the Present Invention Radius of Radius of Radius of curvature of curvature curvature of posterior of anterior posterior surface/Radius Refractive Diopter surface surface of curvature of example Material index (D) (mm) (mm) anterior surface 1 Silicone/hydrogel 1.46 5.0 48.6 48.0 98.8% 6.0 48.5 35.0 72.2% 9.0 26.5 13.0 49.1% 15.0 44.5 10.0 22.7% 20.0 25.6 8.0 31.3% 26.5 12.0 7.5 62.5% 30.0 9.2 7.3 79.3% 36.0 7.1 6.6 92.9% 2 hydrophobic 1.47 5.0 52.5 52.0 99.0% acrylate 6.0 59.0 35.0 59.3% 9.0 25.5 15.0 58.8% 15.0 44.5 11.0 24.7% 20.0 28.7 8.5 29.6% 26.5 17.0 7.0 41.2% 30.0 11.0 7.3 66.4% 36.0 7.8 7.0 89.7% 3 hydrophobic 1.48 5.0 55.1 55.0 99.8% acrylate 6.0 47.1 45.5 96.6% 9.0 74.0 19.5 26.4% 15.0 55.7 11.1 20.0% 20.0 18.5 11.1 60.0% 26.5 14.7 8.1 55.5% 30.0 10.7 8.1 75.7% 36.0 8.0 7.5 93.7% 4 polymethyl 1.49 5.0 60.0 59.5 99.2% methacrylate 6.0 56.0 45.5 81.2% (PMMA) 9.0 30.0 17.0 56.7% 15.0 44.5 13.1 29.4% 20.0 44.7 9.0 20.1% 26.5 29.5 7.0 23.7% 30.0 17.2 7.0 40.7% 36.0 10.9 6.8 62.4% 5 hydrophobic 1.51 5.0 67.0 66.0 98.5% acrylate 6.0 74.0 45.5 61.5% 9.0 65.5 14.9 22.7% 15.0 44.5 15.3 33.6% 20.0 55.5 9.9 17.8% 26.5 53.5 7.2 13.5% 30.0 27.5 7.0 25.5% 36.0 14.4 7.0 48.6% 6 hydrophobic 1.52 5.0 71.0 70.0 98.6% acrylate 6.0 73.0 50.0 68.5% 9.0 55.0 16.6 30.2% 15.0 44.5 16.5 37.1% 20.0 55.5 10.6 19.1% 26.5 55.5 7.6 13.7% 30.0 37.0 7.0 18.9% 36.0 17.0 7.0 41.2% 7 hydrophobic 1.55 5.0 81.0 80.0 98.8% acrylate 6.0 84.0 57.0 67.9% 9.0 58.0 20.0 34.5% 15.0 44.5 20.3 45.6% 20.0 55.0 12.7 23.1% 26.5 55.5 9.0 16.4% 30.0 53.0 7.8 14.7% 36.0 30.8 7.0 22.7%

(50) As can be seen from Table 2, the radius of curvature of the basic spherical surface of the posterior surface of the effective optical area of the posterior chamber IOL of the present invention is substantially in a range of 6.6 mm-80.0 mm. The radius of curvature of the basic spherical surface of the anterior surface of the effective optical area of the posterior chamber IOL of the present invention is substantially in a range of 7.1 mm-84.0 mm.

(51) In Example 1, in another preferred embodiment of the present invention, the posterior chamber IOL is made of silicone or hydrogel with a refractive index 1.46, for example, the material was once used to prepare SI40NB silicone IOL of AMO Inc. of the United State and Akreos hydrogel IOL of Bausch & Lomb Incorporated. As can be seen from Table 2, the radius of curvature of the posterior surface of the effective optical area of the posterior chamber IOL is substantially in a range of 6.6 mm-48.0 mm, and the radius of curvature of the anterior surface of the effective optical area of the posterior chamber IOL is substantially in a range of 7.1 mm-48.6 mm. To better achieve the above advantageous effect of the present invention, the radius of curvature of the posterior surface of the effective optical area is preferably in a range of 7.5 mm-10.0 mm, or more preferably about 8.0 mm.

(52) In Example 2, the posterior chamber IOL is made of hydrophobic acrylate with a refractive index 1.47, for example, the material was once used to prepare AR40e IOL of AMO Inc. of the United State. As can be seen from Table 2, the radius of curvature of the posterior surface of the effective optical area of the posterior chamber IOL is in a range of 7.0 mm-52.0 mm, and the radius of curvature of the anterior surface of the effective optical area of the posterior chamber IOL is in a range of 7.8 mm-59.0 mm. To better achieve the above advantageous effect of the present invention, the radius of curvature of the posterior surface of the effective optical area is preferably in a range of 7.0 mm-11.0 mm, or more preferably about 8.5 mm.

(53) In Example 3, the posterior chamber IOL is made of hydrophobic acrylate which is available from Eyebright Medical Technology (Beijing) Co., Ltd. As can be seen from Table 2, the material for the posterior chamber IOL has a refractive index 1.48. The radius of curvature of the posterior surface of the effective optical area of the posterior chamber IOL is in a range of 7.5 mm-55.0 mm, and the radius of curvature of the anterior surface of the effective optical area of the posterior chamber IOL is in a range of 8.0 mm-74.0 mm. To better achieve the above advantageous effect of the present invention, the radius of curvature of the posterior surface of the effective optical area is preferably in a range of 8.1 mm-19.5 mm, or more preferably about 11.1 mm.

(54) In Example 4, the posterior chamber IOL is made of polymethyl methacrylate (PMMA) which is a commonly-used material for preparing the IOL in the early stage. As can be seen from Table 2, the material for the posterior chamber IOL has a refractive index 1.49. The radius of curvature of the posterior surface of the effective optical area of the posterior chamber IOL is in a range of 6.8 mm-59.5 mm, and the radius of curvature of the anterior surface of the effective optical area of the posterior chamber IOL is in a range of 10.9 mm-60.0 mm. To better achieve the above advantageous effect of the present invention, the radius of curvature of the posterior surface of the effective optical area is preferably in a range of 7.0 mm-13.1 mm, or more preferably about 9.0 mm.

(55) In Example 5, the posterior chamber IOL is made of hydrophobic acrylate with a refractive index 1.51, and for example this material was once used by HOYA CORPORATION to prepare AF-1 model IOL. As can be seen from Table 2, the radius of curvature of the posterior surface of the effective optical area of the posterior chamber IOL is in a range of 7.0 mm-66.0 mm, and the radius of curvature of the anterior surface of the effective optical area of the posterior chamber IOL is in a range of 14.4 mm-74.0 mm. To better achieve the above advantageous effect of the present invention, the radius of curvature of the posterior surface of the effective optical area is preferably in a range of 7.2 mm-15.3 mm, or more preferably about 9.9 mm.

(56) In Example 6, the posterior chamber IOL is made of hydrophobic acrylate which is available from Eyebright Medical Technology (Beijing) Co., Ltd. As can be seen from Table 2, the material for the posterior chamber IOL has a refractive index 1.52. The radius of curvature of the posterior surface of the effective optical area of the posterior chamber IOL is in a range of 7.0 mm-70.0 mm, and the radius of curvature of the anterior surface of the effective optical area of the posterior chamber IOL is in a range of 17.0 mm-73.0 mm. To better achieve the above advantageous effect of the present invention, the radius of curvature of the posterior surface of the effective optical area is preferably in a range of 7.6 mm-16.5 mm, or more preferably about 10.6 mm.

(57) In Example 7, the posterior chamber IOL is made of hydrophobic acrylate with a refractive index 1.55, for example, the material was once used by ALCON CORPORATION of the United State to prepare Acrys of series IOLs. As can be seen from Table 2, the radius of curvature of the posterior surface of the effective optical area of the posterior chamber IOL is in a range of 7.0 mm-80.0 mm, and the radius of curvature of the anterior surface of the effective optical area of the posterior chamber IOL is in a range of 30.8 mm-84.0 mm. To better achieve the above advantageous effect of the present invention, the radius of curvature of the posterior surface of the effective optical area is preferably in a range of 9.0 mm-20.3 mm, or more preferably about 12.7 mm.

(58) Besides, as further can be seen from Table 2, the radius of curvature of the posterior surface of the effective optical area of the posterior chamber IOL is smaller than that of the anterior surface of the effective optical area. To better achieve the above advantageous effect of the present invention, the radius of curvature of the posterior surface of the effective optical area is 17.8%-60.0% of the radius of curvature of the anterior surface of the effective optical area; more preferably, the radius of curvature of the posterior surface of the effective optical area is 20.0%-45.6% of the radius of curvature of the anterior surface of the effective optical area.

(59) Certainly, those skilled in the art, upon viewing Table 2, can appreciate that the radius of curvature of the posterior surface of the effective optical area of the posterior chamber IOL is substantially equal to that of the anterior surface of the effective optical area.

(60) (II.1) A High Order Aspherical Surface Design of the IOL Effective Optical Area

(61) In order to eliminate or reduce high order aberration (including spherical aberration and comatic aberration) of the prior-art IOL products to improve imaging quality, the effective optical area posterior surface or anterior surface of the obviously rearwardly convex posterior chamber IOL according to an embodiment of the present invention adopts a high order aspherical surface design and does not adopt a conventional single Q-value aspherical surface design (the single Q-value aspherical surface design can only complement spherical aberration).

(62) A complementation principle of the aspherical surface of the effective optical area of the obviously rearwardly convex posterior chamber IOL of the present invention is that extra spherical aberration generated by the aspherical surface offsets the spherical aberration generated by the basic spherical surface, and the extra comatic aberration generated by the aspherical surface offsets the comatic aberration generated by the basic spherical surface.

(63) In the present application, the high order aspherical surface design utilizes various variables upon designing a plural high order equation coefficient, and the resultant aspherical surface shape is more complicated than the basic spherical surface shape. The high order aspherical surface design can not only correct the spherical aberration but also correct high order aberration of other types, and reduce the lens's sensitivity to the implantation site.

(64) To more accurately describe the surface shape of the effective optical area of the IOL of the present invention, a two-dimensional coordinate system is established with an effective optical area surface apex adopting a higher order aspherical surface design in the obviously rearwardly convex posterior chamber IOL as an original point, a longitudinal coordinate axis Y of the coordinate system is tangential with the effective optical area surface and passes through the effective optical area surface apex O; a horizontal coordinate axis Z of the coordinate system is parallel to an ocular axis direction D-D and is at an angle of 90 degrees relative to the longitudinal coordinate axis Y and passes through the effective optical area surface apex O as shown in FIG. 5. Points on the effective optical area surface adopting the high order aspherical surface design in the obviously rearwardly convex posterior chamber IOL of the present invention are in rotational symmetrical relationship with the horizontal coordinate axis Z which passes through the effective optical area surface apex O and is parallel to an ocular axis direction D-D as shown in FIG. 5. Therefore, the surface shape of the effective optical area surface adopting the high order aspherical surface design in the obviously rearwardly convex posterior chamber IOL of the present invention can be restored through rotational symmetrical conversion on the premise of defining the coordination relationship of the effective optical area surface adopting the high order aspherical surface design in the obviously rearwardly convex posterior chamber IOL of the present invention on a plane constituted by the longitudinal coordinate axis Y and the horizontal coordinate axis Z. Respective points on the effective optical area surface adopting the high order aspherical surface design in the obviously rearwardly convex posterior chamber IOL of the present invention on the plane constituted by the longitudinal coordinate axis Y and the horizontal coordinate axis Z may be represented as (Z, y). As shown in FIG. 12, Z.sub.asph is a Z value of any point of the aspherical surface shape on a curve on the two-dimensional coordination system plane YZ, and Z.sub.sph is a Z value Z of the spherical surface shape on a curve on the two-dimensional coordination system plane YZ.

(65) Referring to FIG. 10, a curve of the aspherical surface of the obviously rearwardly convex posterior chamber IOL of the present invention on the two-dimensional coordinate system plane YZ satisfies the following expression of higher order aspherical surface design:

(66) $\begin{matrix} Z (y) = \frac{{cy}^{2}}{1 + \sqrt{1 - c^{2} y^{2}}} + {.Math.}_{i = m}^{n} A_{2 i} .Math. y^{2 i} & (4) \end{matrix}$

(67) Wherein Z(y) is an expression of the curve of the aspherical surface of the IOL effective optical area on the YZ plane, c is a reciprocal of a radius of curvature of the surface of the basic spherical surface of the effective optical area, y is a vertical distance of any point on the curve from the horizontal coordinate axis Z, A.sub.2i is a higher-order term coefficient of the aspherical surface, m, n are both an integer greater than or equal to 1 and nm, these terms reflect the magnitude of difference between the aspherical surface shape and the basic spherical surface shape. It can be seen from the above equation that the higher order aspherical surface can be considered as a superposition of the basic spherical surface term

(68) 0 $\frac{{cy}^{2}}{1 + \sqrt{1 - c^{2} y^{2}}}$
and a deviation quantity, wherein the aspherical surface higher order coefficient

(69) ${.Math.}_{i = m}^{n} A_{2 i} .Math. y^{2 i}$
is a superposed term.

(70) Points on the convex aspherical surface shape are obtained in a way that the curve rotates around the horizontal coordinate axis (Z) for symmetry variation.

(71) Table 3 lists parameter values A.sub.2i (m=2 and n=5) of superposed terms in equation (4) after increasing the higher order aspherical surface design on various Table 2-listed basic spherical surfaces of the IOL effective optical area according to a plurality of preferred embodiments of the present invention. The higher order coefficient in Table 2 is obtained through ZEMAX simulation, the human eye model adopted by the simulation is Liou eye model, and optimization is performed to allow a desired lens to have a better imaging quality in the case of off-centering 0.5 mm and inclining 5.

(72) Those skilled in the art should appreciate that the higher order coefficients in the superposed terms of the equation (4) will vary with different human eye models used.

(73) TABLE-US-00003 TABLE 3 Parameter values (m = 2 and n = 5) of superposed terms of the aspherical surface shape expression of the present invention after increasing the higher order aspherical surface design on various basic spherical surfaces of the IOL effective optical area posterior surface Refractive Material index A.sub.4 A.sub.6 A.sub.8 A.sub.10 Silicone or 1.45 3.249E003 2.182E003 4.227E004 3.113E005 hydrogel Silicone or 1.46 2.804E003 1.860E003 3.201E004 1.876E005 hydrogel Hydrophobic 1.47 1.776E003 1.302E003 2.294E004 1.590E005 acrylate Hydrophobic 1.48 2.431E004 2.897E004 5.417E005 2.940E006 acrylate (the present invention) Hydrophobic 1.48 1.518E003 1.140E003 2.503E004 2.406E005 acrylate polymethyl 1.49 1.198E003 8.292E004 9.372E005 1.303E006 methacrylate (PMMA) Hydrophobic 1.51 4.661E004 3.294E004 2.288E005 8.575E006 acrylate Hydrophobic 1.52 5.663E004 3.534E004 1.301E005 7.467E006 acrylate Hydrophobic 1.55 1.566E003 1.069E003 1.667E004 8.009E006 acrylate Hydrophobic 1.56 1.128E003 6.244E004 2.149E004 2.196E005 acrylate

(74) In addition, those skilled in the art can appreciate that if the aspherical surface design is added to the basic aspherical surface of the IOL effective optical area anterior surface, the higher order aspherical coefficients thereof are in an positive-negative opposite relationship with the corresponding higher order aspherical surface coefficients listed in Table 2. Those skilled in the art can also appreciate that the imaging quality will not be affected when the aspherical surface design is added to any one of the anterior surface and posterior surface of the IOL effective optical area.

(75) As compared with the prior-art IOL adopting a spherical surface design and a prior-art IOL adopting a single Q-value aspherical surface design, the obviously rearwardly convex posterior chamber IOL with an effective optical area adopting the aspherical surface design according to the preferred embodiment of the present invention further improves the imaging quality of the IOL, as shown in FIGS. 13-17.

(76) FIG. 13 shows longitudinal aberration graphs of IOL adopting three different posterior surface designs (spherical surface design with obviously convex posterior surface, spherical surface design with a flat posterior surface and aspherical surface design with obviously convex posterior surface) with a 5 mm light transmission aperture and a 20D diopter in a human eye model. The horizontal coordinate represents different aperture positions (represented by a percentage of aperture size), and the longitudinal coordinate represents the magnitude of the longitudinal aberration. As for an IOL at a central position, the longitudinal aberration is chiefly the spherical aberration. A spherical surface IOL with a larger radius of curvature of the posterior surface has a relatively flat posterior surface, which conforms to the minimization design principle of aberration (the minimization of the aberration is achieved by wholly curving surface shapes of two surfaces of the IOL), and has a smaller aberration (as shown by the dotted line in the figure); a spherical surface IOL with a small radius of curvature of the posterior surface has an obviously convex posterior surface, and has an obviously increased aberration (as shown by the thin solid line) as compared with the spherical surface IOL with a flat posterior surface. One of surfaces of the IOL adopts an aspherical surface design, can effectively compensate aberration caused by the surface shape and obviously reduce the aberration (as shown by the thick solid line).

(77) FIG. 14A, FIG. 14B and FIG. 14C respectively show higher order aberration distribution diagrams (with a pupil diameter of 5.0 mm) when a spherical surface IOL, a single Q-value aspherical surface IOL and a higher order aspherical surface IOL are in a central position, a off-centered state and an inclined state respectively. When the IOL is at the central position in the human eye capsule bag, the spherical surface IOL has a larger aberration, the single Q-value aspherical surface may correct aberration and does not involve other higher order aberrations (or involves a very small higher order aberration), the higher order aspherical surface may also correct the aberration but has a slightly larger surplus aberration than the single Q-value aspherical value. When the IOL is in a off-centered or inclined state in the human eye capsule bag, the spherical surface and aspherical surface both have the spherical aberration and the comatic aberration, but the single Q-value aspherical surface generates the largest comatic aberration. The higher order aspherical surface generates a smaller comatic aberration than the single Q value, and has a higher order aberration generally smaller than the spherical surface and the single Q-value aspherical surface.

(78) In this art, for either the large higher order aberration system or smaller higher order aberration system, MTF graph is an effective, objective and full image quality evaluating method. In the practical sense, a MTF value represents contrast and sharpness of an optical image, is measured by how many lines are presented in a one-millimeter scope, and has a measure unit lp/mm.

(79) FIG. 15 is a modulation transfer function (MTF) graph as actually measured in a human eye model with a cornea aberration when a spherical surface IOL, a single Q-value aspherical surface IOL and a higher order aspherical surface IOL with a small radius of curvature at a posterior surface are at a central position (with a pupil diameter 5.0 mm). As can be seen from the figure, the spherical surface IOL at the central position has a larger spherical aberration, with the MTF curve lower; and the single Q-value aspherical surface IOL and the IOL of the present invention both can correct the spherical aberration very well.

(80) FIG. 16 is a MTF graph as actually measured in a human eye model with a cornea aberration when a spherical surface IOL, a single Q-value aspherical surface IOL and a higher order aspherical surface IOL with a small radius of curvature at a posterior surface are off-centered 1 mm in the human eye capsule bag (with a pupil diameter 5.0 mm). As can be seen from the figure, when being off-centered 1 mm in the human eye capsule bag, the IOL of the present invention is apparently advantageous than other types of IOLs in medium and low frequency bands, particularly below 50 lp/mm (50 lp/mm indicates 0.5 vision), but not distinct from other types of IOLs at the high frequency bands. Generally speaking, the IOL of the present invention is rather advantageous than the remaining types of IOLs.

(81) FIG. 17 is a MTF graph as actually measured in a human eye model with a cornea aberration when a spherical surface IOL, a single Q-value aspherical surface IOL and a higher order aspherical surface IOL with a small radius of curvature at a posterior surface are off-centered 0.5 mm and inclined 5 (with a pupil diameter 5.0 mm). It can be seen from the figure that upon off-centering and inclination at the same time, the IOL of the present invention is obviously advantageous and exhibits excellent optical performance at the 100 lp/mm full frequency band.

(82) It can be seen from the above figures that the obviously rearwardly convex posterior chamber IOL adopting the aspherical surface design according to a preferred embodiment of the present invention solves the problem that the lens surplus aberration is larger than the ordinary surface shape design because the radius of curvature of the IOL posterior surface is smaller than that of the anterior surface and solves the problem that the ordinary aspherical surface (single Q-value aspherical surface) IOL is too sensitive to disalignment of implantation (off-centering and inclination occurring during the surgery).

(83) To conclude, the present invention belongs to the field of design of the effective optical area of the IOL. Regarding the design of the IOL having a posterior surface with a smaller radius of curvature, the present invention adopts the higher order aspherical surface design to correct the spherical aberration of the lens and other higher order aberration in the case of a large aperture and disalignment, and improve the imaging quality of the IOL.

(84) (II.2) Toric Surface Design of the Effective Optical Area of the IOL

(85) To correct the refractive power and meanwhile correct the cornea astigmatism after removal of the lens from a cataract patient with astigmatism and thereby further improve visual quality, the effective optical area anterior surface or posterior surface of the obviously rearwardly convex posterior chamber IOL of the present invention may adopt a toric surface design.

(86) Astigmatism property, astigmatism degree and axial position of an astigmatic eye is jointly decided by cornea astigmatism and lens astigmatism. Regarding a cataract patient, after the natural lens is removed, the surface shape defect of the cornea is a main cause for astigmatism. Astigmatism is a vector and can be jointly expressed by magnitude and angle. Briefly speaking, the cornea with astigmatism may be understood as a sum of refractive power of a spherical lens and a cylindrical lens, or as a toric surface with inconsistent diopters in the horizontal direction and vertical direction.

(87) The cause for forming cornea astigmatism may be directed to the cornea as a kind of Toric surface. A mode by which the IOL corrects the cornea astigmatism is to design the IOL as the Toric surface and allow a maximum refractive power axis to coincide with a minimum refractive power axis of the cornea.

(88) To correct pure astigmatism (not including diopter), a cylindrical lens may be used in a way that the refractive power of the cylindrical lens is equal to the magnitude of the cornea astigmatism and opposite in direction. In a cataract surgery in which a lens is implanted, the diopter of the lens needs to be combined with correction of astigmatism so that both the refractive power and the cornea astigmatism can be corrected.

(89) Therefore, the Toric IOL design has the following key points: the first is to perform a basic refractive power design, namely, to satisfy the human eye's requirements for refraction; the second is, on the basis of the basic refractive power design, to use Toric surface shape to additionally provide cylinder power in a certain direction to allow it equal to the magnitude of an additional cylinder power of the cornea and opposite in direction.

(90) Steps for designing the Toric IOL according to the present invention include: designing a basic surface shape of the Toric IOL to satisfy the human eye's requirement for correction of the total refractive power. As far as the present invention is concerned, the IOL needs to reach a refraction range of 5.0D-36.0D in the human eye. Then, there comes to a step of building astigmatism-accompanied cornea and human eye model. Finally, there is a step of additionally providing cylinder power on the basic surface shape of the Toric IOL and correcting cornea astigmatism. As for the present invention, the cylindrical lens degree may be additionally provided by using the surface shape of the toric surface for the effective optical area anterior surface or effective optical area posterior surface.

(91) The Toric surface of the Toric IOL has an axial marker which indicates a minimum refractive power direction of the IOL, and the axial marker needs to be made coincide with a direction with a maximum human eye cornea astigmatism refractive power during a surgical procedure. Studies show that when the axial direction of the Toric IOL rotates more than 5 relative to the axial position of the human eye cornea, the Toric IOL will lose the function to correct astigmatism. Further improving the optical performance of the implanted IOL and meanwhile facilitating the surgeon's mastery of the axial position of the IOL during implantation are factors to be considered in the surface shape design of the effective optical area of the astigmatism-correcting IOL according to the present invention. Therefore, those skilled I the art appreciate that the Toric surface and an ideal position of the axial marker thereof should be located at the IOL anterior surface (in the direction of an anterior chamber).

(92) Most cataract patients with astigmatism have an astigmatic cylinder power in a range of 0.5D-2.5D (data source: ALCON Toric IOL product manual). Therefore, the Toric IOL of the present invention should consider the cylinder power mainly in the range of 0.5D-2.5D upon designing.

(93) With reference to FIG. 18, an anterior surface of the effective optical area of the obviously rearwardly convex posterior chamber IOL according to an embodiment of the present invention comprises: an optic consisting of an effective optical area and an effective optical area edge; at least two haptics connected to the optic. The anterior surface of the effective optical area is a convex toric surface which is formed by superposing a basic spherical surface with a radius of curvature in a range of 7.1 mm-84.0 mm with a deviation quantity relative to the basic spherical surface, and a radius of curvature of the posterior surface of the effective optical area is in a range of 6.6 mm-80.0 mm. A two-dimensional coordinate system is established with an effective optical area anterior surface apex in the posterior chamber IOL as an original point, a longitudinal coordinate axis Y of the coordinate system is tangential with the effective optical area anterior surface and passes through the effective optical area anterior surface apex O; a horizontal coordinate axis Z of the coordinate system is parallel to an ocular axis direction D-D and is at an angle of 90 degrees relative to the longitudinal coordinate axis Y and passes through the effective optical area anterior surface apex O. A curve of the toric surface on the two-dimensional coordinate system plane YZ satisfies the following expression:

(94) $\begin{matrix} Z (y) = \frac{{cy}^{2}}{1 + \sqrt{1 - (1 + k) c^{2} y^{2}}} + {.Math.}_{i = m}^{n} A_{2 i} .Math. y^{2 i} & (5) \end{matrix}$

(95) Wherein Z(y) is an expression of the curve of the toric surface of the IOL effective optical area on the YZ plane, c is a reciprocal of a radius of curvature of the surface of the basic spherical surface of the effective optical area, y is a vertical distance of any point on the curve from the horizontal coordinate axis Z, A.sub.2i is a higher-order term coefficient of the aspherical surface, and m, n are both an integer greater than or equal to 1 and

(96) Points on the convex toric surface are obtained in a way that the curve rotates about a straight line d-d parallel to the longitudinal coordinate axis Y one round with a certain anterior surface rotation radius R.

(97) Characteristics of the toric surface are as follows: the magnitudes of the refractive power in the horizontal direction and vertical direction are different, the refractive power in the vertical direction depends on a radius of curvature of a rotation curve, the refractive power in the horizontal direction depends on the anterior surface rotation radius around which the curve rotates, and the refractive power between the horizontal direction and vertical direction depends on the surface shape formed by rotation of the curve. A refractive power distribution effect of the toric surface is equivalent to the combination of the basic spherical surface and the cylindrical surface.

(98) Table 4 below lists a correspondence relationship between additional cylinder power and a correctable cornea cylinder power of a Toric IOL according to another embodiment of the present invention.

(99) TABLE-US-00004 TABLE 4 Lens cylinder 0.5D 1.00D 1.50D 2.25D 3.00D 4.00D 4.50D 5.0D powers Cornea cylinder 0.39D 0.70D 1.02D 1.49D 1.97D 2.61D 2.93D 3.25D powers

(100) Table 5 lists a radius of curvature r of an anterior surface standard YZ curve, anterior surface rotation radius R and a radius of curvature of a posterior surface corresponding to different cylinder power in a rearwardly convex Toric IOL with different materials and different degrees.

(101) TABLE-US-00005 TABLE 5 Radius of curvaturer (mm) of cylinder cylinder cylinder cylinder cylinder cylinder cylinder cylinder a basic power power power power power power power power curve of 0.5D; 1.0D; 1.5D; 2.25D; 3.0D; 4.0D; 4.5D; 5.0D; an Radius of anterior anterior anterior anterior anterior anterior anterior anterior Refractive anterior curvature surface surface surface surface surface surface surface surface index and surface (mm) of rotation rotation rotation rotation rotation rotation rotation rotation material Diopter on YZ posterior radius R radius R radius R radius R radius R radius R radius R radius R property (D) plane surface (mm) (mm) (mm) (mm) (mm) (mm) (mm) (mm) 1.46 5.0 48.600 48.00 40.64 34.92 30.61 25.83 22.34 18.93 17.59 16.42 silicone or 6.0 48.500 35.00 40.57 34.86 30.57 25.80 22.32 18.91 17.57 16.41 hydrogel 9.0 26.500 13.00 23.94 21.83 20.07 17.90 16.15 14.29 13.51 12.81 15.0 44.500 10.00 37.73 32.75 28.93 24.62 21.43 18.27 17.02 15.92 20.0 25.600 8.00 23.20 21.22 19.55 17.48 15.81 14.02 13.27 12.60 26.5 12.000 7.50 11.45 10.94 10.48 9.85 9.30 8.65 8.36 8.09 30.0 9.200 7.30 8.87 8.56 8.28 7.88 7.53 7.09 6.90 6.71 36.0 7.100 6.60 6.90 6.72 6.54 6.29 6.06 5.78 5.65 5.52 1.47 5.0 52.500 52.00 43.90 37.72 33.07 27.90 24.13 20.45 19.00 17.74 hydrophobic 6.0 59.000 35.00 48.35 40.96 35.53 29.64 25.42 21.37 19.79 18.43 acrylate 9.0 25.500 15.00 23.28 21.42 19.84 17.85 16.23 14.48 13.74 13.07 15.0 45.500 11.00 38.90 33.97 30.15 25.79 22.54 19.29 18.00 16.87 20.0 28.700 8.50 25.92 23.64 21.72 19.37 17.47 15.46 14.61 13.86 26.5 17.000 7.00 15.99 15.09 14.28 13.22 12.31 11.28 10.82 10.40 30.0 11.000 7.30 10.57 10.17 9.79 9.29 8.83 8.28 8.03 7.80 36.0 7.800 7.00 7.58 7.37 7.17 6.90 6.64 6.33 6.18 6.04 1.48 5.0 55.100 55.00 46.09 39.62 34.74 29.32 25.36 21.50 19.97 18.65 hydrophobic 6.0 47.138 45.50 40.39 35.33 31.39 26.90 23.53 20.17 18.82 17.64 acrylate 9.0 74.026 19.50 58.63 48.54 41.41 33.94 28.75 23.88 22.01 20.42 15.0 55.743 11.10 46.54 39.95 34.99 29.50 25.50 21.59 20.06 18.73 20.0 18.459 11.10 17.32 16.32 15.43 14.26 13.25 12.11 11.62 11.16 26.5 14.708 8.10 13.98 13.32 12.72 11.91 11.20 10.38 10.01 9.67 30.0 10.688 8.10 10.30 9.94 9.60 9.13 8.71 8.20 7.97 7.75 36.0 8.000 7.50 7.78 7.57 7.37 7.09 6.84 6.52 6.37 6.23 1.49 5.0 60.000 59.50 50.22 43.18 37.87 31.97 27.66 23.45 21.79 20.35 polymethyl 6.0 56.000 45.50 47.38 41.07 36.24 30.80 26.78 22.81 21.24 19.87 methacrylate 9.0 30.000 17.00 27.34 25.11 23.22 20.86 18.93 16.86 15.99 15.20 (PMMA) 15.0 44.500 13.10 38.88 34.52 31.04 26.97 23.84 20.64 19.35 18.20 20.0 44.700 9.00 39.03 34.64 31.14 27.04 23.89 20.68 19.38 18.24 26.5 29.500 7.00 26.92 24.76 22.92 20.61 18.73 16.70 15.84 15.07 30.0 17.200 7.00 16.29 15.47 14.73 13.75 12.88 11.89 11.45 11.04 36.0 10.900 6.80 10.53 10.18 9.85 9.40 8.99 8.49 8.27 8.05 1.51 5.0 67.000 66.00 56.18 48.37 42.47 35.90 31.09 26.38 24.52 22.90 hydrophobic 6.0 74.000 45.50 61.02 51.92 45.18 37.81 32.52 27.40 25.40 23.67 acrylate 9.0 65.500 14.90 55.12 47.59 41.86 35.46 30.76 26.14 24.31 22.73 15.0 44.500 15.30 39.45 35.44 32.16 28.25 25.18 22.00 20.69 19.53 20.0 55.500 9.90 47.87 42.08 37.54 32.31 28.36 24.39 22.79 21.39 26.5 53.500 7.20 46.37 40.92 36.61 31.62 27.83 23.99 22.44 21.08 30.0 27.500 7.00 25.49 23.75 22.23 20.29 18.65 16.85 16.07 15.36 36.0 14.400 70.00 13.83 13.30 12.81 12.14 11.54 10.82 10.49 10.19 1.52 5.0 71.000 50.00 59.52 51.23 44.97 38.00 32.91 27.91 25.95 24.24 hydrophobic 6.0 73.000 16.60 60.92 52.26 45.76 38.57 33.33 28.22 26.21 24.47 acrylate 9.0 55.000 16.50 47.85 42.34 37.97 32.88 29.00 25.05 23.45 22.05 15.0 44.500 10.60 39.70 35.83 32.65 28.82 25.79 22.62 21.31 20.14 20.0 55.500 7.60 48.23 42.64 38.21 33.06 29.14 25.15 23.54 22.13 26.5 55.500 7.00 48.23 42.64 38.21 33.06 29.14 25.15 23.54 22.13 30.0 37.000 7.00 33.62 30.81 28.43 25.47 23.08 20.51 19.42 18.45 36.0 17.000 70.00 16.25 15.56 14.93 14.07 13.31 12.41 12.01 11.63 1.55 5.0 81.000 80.00 68.11 58.76 51.67 43.75 37.93 37.93 29.96 28.00 hydrophobic 6.0 84.000 57.00 70.22 60.32 52.87 44.61 38.58 38.58 30.36 28.35 acrylate 9.0 58.000 20.00 51.08 45.63 41.24 36.03 31.99 31.99 26.13 24.63 15.0 44.500 20.30 40.31 36.84 33.92 30.32 27.40 27.40 22.99 21.82 20.0 55.000 12.70 48.74 43.75 39.70 34.85 31.06 31.06 25.50 24.07 26.5 55.500 9.00 49.13 44.07 39.96 35.05 31.21 31.21 25.61 24.16 30.0 53.000 7.80 47.16 42.48 38.64 34.03 30.41 30.41 25.07 23.68 36.0 30.800 7.00 28.73 26.92 25.33 23.27 21.51 21.51 18.69 17.91

(102) The following can be seen from data of examples in Table 5:

(103) Regarding the obviously rearwardly convex posterior chamber IOL made of silicone or hydrogel with a refractive index 1.46 and having the effective optical area anterior surface adopting the toric surface design, the radius of curvature of the basic curve of the effective optical area anterior surface on the YZ plane is in a range of 7.1 mm-48.6 mm; when the additional cylinder power of the toric surface is in a range of 0.5-5.0D, the anterior surface rotation radius is in a range of 5.52-40.64 mm. To better achieve the above advantageous effect of the present invention, the radius of curvature of the basic curve of the effective optical area anterior surface on the YZ plane is preferably in a range of 9.2 mm-44.5 mm; when the additional cylinder power of the toric surface is in a range of 1.0-4.0D, the anterior surface rotation radius is in a range of 7.09-32.75 mm. More preferably, the radius of curvature of the basic curve of the effective optical area anterior surface on the YZ plane is about 12.0 mm; when the additional cylinder power of the toric surface is 2.25D, the anterior surface rotation radius is about 9.85 mm.

(104) Regarding the obviously rearwardly convex posterior chamber IOL made of hydrophobic acrylate with a refractive index 1.47 and having the effective optical area anterior surface adopting the toric surface design, the radius of curvature of the basic curve of the effective optical area anterior surface on the YZ plane is in a range of 7.8 mm-59.0 mm; when the additional cylinder power of the toric surface is in a range of 0.5-5.0D, the anterior surface rotation radius is in a range of 6.04-48.35 mm. To better achieve the above advantageous effect of the present invention, the radius of curvature of the basic curve of the effective optical area anterior surface on the YZ plane is preferably in a range of 11.0 mm-45.5 mm; when the additional cylinder power of the toric surface is in a range of 1.0-4.0D, the anterior surface rotation radius is in a range of 8.28-33.97 mm. More preferably, the radius of curvature of the basic curve of the effective optical area anterior surface on the YZ plane is about 17.0 mm; when the additional cylinder power of the toric surface is 2.25D, the anterior surface rotation radius is about 13.22 mm.

(105) Regarding the obviously rearwardly convex posterior chamber IOL made of hydrophobic acrylate with a refractive index 1.48 and having the effective optical area anterior surface adopting the toric surface design, the radius of curvature of the basic curve of the effective optical area anterior surface on the YZ plane is in a range of 8.0 mm-74.0 mm; when the additional cylinder power of the toric surface is in a range of 0.5-5.0D, the anterior surface rotation radius is in a range of 6.23-58.63 mm. To better achieve the above advantageous effect of the present invention, the radius of curvature of the basic curve of the effective optical area anterior surface on the YZ plane is preferably in a range of 10.69 mm-55.74 mm; when the additional cylinder power of the toric surface is in a range of 1.0-4.0D, the anterior surface rotation radius is in a range of 8.2-39.95 mm. More preferably, the radius of curvature of the basic curve of the effective optical area anterior surface on the YZ plane is about 14.71 mm; when the additional cylinder power of the toric surface is 2.25D, the anterior surface rotation radius is about 11.91 mm.

(106) Regarding the obviously rearwardly convex posterior chamber IOL made of polymethyl methacrylate (PMMA) with a refractive index 1.49 and having the effective optical area anterior surface adopting the toric surface design, the radius of curvature of the basic curve of the effective optical area anterior surface on the YZ plane is in a range of 10.9 mm-60.0 mm; when the additional cylinder power of the toric surface is in a range of 0.5-5.0D, the anterior surface rotation radius is in a range of 8.05-59.50 mm. To better achieve the above advantageous effect of the present invention, the radius of curvature of the basic curve of the effective optical area anterior surface on the YZ plane is preferably in a range of 17.2 mm-44.5 mm; when the additional cylinder power of the toric surface is in a range of 1.0-4.0D, the anterior surface rotation radius is in a range of 11.89-34.64 mm. More preferably, the radius of curvature of the basic curve of the effective optical area anterior surface on the YZ plane is about 29.5 mm; when the additional cylinder power of the toric surface is 2.25D, the anterior surface rotation radius is about 20.61 mm.

(107) Regarding the obviously rearwardly convex posterior chamber IOL made of hydrophobic acrylate with a refractive index 1.51 and having the effective optical area anterior surface adopting the toric surface design, the radius of curvature of the basic curve of the effective optical area anterior surface on the YZ plane is in a range of 14.4 mm-74.0 mm; when the additional cylinder power of the toric surface is in a range of 0.5-5.0D, the anterior surface rotation radius is in a range of 10.19-61.02 mm. To better achieve the above advantageous effect of the present invention, the radius of curvature of the basic curve of the effective optical area anterior surface on the YZ plane is preferably in a range of 27.5 mm-55.5 mm; when the additional cylinder power of the toric surface is in a range of 1.0-4.0D, the anterior surface rotation radius is in a range of 16.85-42.08 mm. More preferably, the radius of curvature of the basic curve of the effective optical area anterior surface on the YZ plane is about 53.5 mm; when the additional cylinder power of the toric surface is 2.25D, the anterior surface rotation radius is about 31.62 mm.

(108) Regarding the obviously rearwardly convex posterior chamber IOL made of hydrophobic acrylate with a refractive index 1.52 and having the effective optical area anterior surface adopting the toric surface design, the radius of curvature of the basic curve of the effective optical area anterior surface on the YZ plane is in a range of 17.0 mm-73.0 mm; when the additional cylinder power of the toric surface is in a range of 0.5-5.0D, the anterior surface rotation radius is in a range of 11.63-60.92 mm. To better achieve the above advantageous effect of the present invention, the radius of curvature of the basic curve of the effective optical area anterior surface on the YZ plane is preferably in a range of 37.0 mm-44.5 mm; when the additional cylinder power of the toric surface is in a range of 1.0D-4.0D, the anterior surface rotation radius is in a range of 20.51-42.64 mm. More preferably, the radius of curvature of the basic curve of the effective optical area anterior surface on the YZ plane is about 55.5 mm; when the additional cylinder power of the toric surface is 2.25D, the anterior surface rotation radius is about 33.06 mm.

(109) Regarding the obviously rearwardly convex posterior chamber IOL made of hydrophobic acrylate with a refractive index 1.55 and having the effective optical area anterior surface adopting the toric surface design, the radius of curvature of the basic curve of the effective optical area anterior surface on the YZ plane is in a range of 30.8 mm-84.0 mm; when the additional cylinder power of the toric surface is in a range of 0.5-5.0D, the anterior surface rotation radius is in a range of 17.91-70.22 mm. To better achieve the above advantageous effect of the present invention, the radius of curvature of the basic curve of the effective optical area anterior surface on the YZ plane is preferably in a range of 44.5 mm-55.5 mm; when the additional cylinder power of the toric surface is in a range of 1.0D-4.0D, the anterior surface rotation radius is in a range of 30.41-44.07 mm. More preferably, the radius of curvature of the basic curve of the effective optical area anterior surface on the YZ plane is about 55.5 mm; when the additional cylinder power of the toric surface is 2.25D, the anterior surface rotation radius is about 35.05 mm.

(110) Certainly, those skilled in the art may appreciate that the posterior surface of the effective optical area of the Toric IOL of the present invention may adopt a spherical surface design or other designs such as adding a higher order aspherical surface design on the basic spherical surface.

(111) As compared with ordinary aspherical surface IOL in the prior art, the anterior surface of the effective optical area of the Toric IOL of the present invention adopts a toric surface design and thereby improves the visual quality of the cataract patient with astigmatism, as shown in FIGS. 19A, 19B, 20A and 20B.

(112) FIG. 19A and FIG. 19B are respectively a point spread function contrast diagram after an ordinary aspherical surface intraocular lens and Toric intraocular lens of the present invention are respectively implanted into a human eye with corneal astigmatism obtained through simulation by adopting ZEMAX, wherein the human eye model has 2.9D corneal astigmatism. It can be seen after comparison of FIG. 19A and FIG. 19B that the human eye in which the ordinary aspherical surface IOL is implanted suffers from astigmatism, the point spread function is in a straight line shape, the imaging situation in one direction (longitudinal direction) is excellent while and the higher order aberration in another direction (horizontal direction) is extremely great. After implantation of Toric IOL, the point spread function is in a dot shape. Although partial astigmatism still exists the human eye, it is already corrected substantially (please note the two figures are in different scales).

(113) FIG. 20A and FIG. 20B are respectively an MTF contrast diagram after an ordinary aspherical intraocular lens and Toric intraocular lens of the present invention are respectively implanted into a human eye with corneal astigmatism obtained through simulation by adopting ZEMAX, wherein the human eye model has 2.9D corneal astigmatism. It can be seen after comparison of FIG. 20A and FIG. 20B that for the human eye in which the ordinary aspherical surface IOL, MTF reaches a diffraction extremity and images are formed very well in one direction, while MTF falls to an extremely low level in another direction. With the Toric IOL of the present invention being implanted, MTF in two directions both reaches a level approximate to the diffraction extremity.

(114) As can be seen from the above figures, the obviously rearwardly convex Toric IOL with the effective optical area anterior surface adopting the toric surface according to an embodiment of the present invention correct the refractive power as well as the corneal astigmatism at the same time, thereby improving the visual quality of the cataract patient with the astigmatism.

(115) In another toric surface design, in order to eliminate or reduce the higher order aberration (including the spherical aberration and comatic aberration) of the IOL product in the prior art and thereby improve the imaging quality, the anterior surface of the effective optical area of the posterior chamber IOL of the present invention adopts the toric surface design and the posterior surface of the effective optical area of the posterior chamber IOL of the present invention adopts a higher order aspherical surface design.

(116) The following Table 6 lists surface shape parameters of one preferred embodiment of the posterior chamber IOL of the present invention adopting the toric surface design and a comparative example in the prior art. Both the preferred embodiment of the present invention and the comparative example of the prior art are made of hydrophobic acrylate and this material is available from Eyebright Medical Technology (Beijing) Co., Ltd. The material of the posterior chamber IOL has a refractive index 1.48 (20). The refractive index of the material is proper, and can effectively reduce occurrence rate of dazzling and ghosting. The posterior chamber IOL according to the following preferred embodiment of the present invention all can reach 20.0D diopter (the additional cylinder power is 2.5D). In Table 6, Ra is a radius of curvature of the IOL anterior surface (the measure unit is millimeter), Rp is a radius of curvature of the IOL posterior surface (the measure unit is millimeter), the value of the radius of curvature is a positive number, which indicates that the surface is outwardly convex relative to a longitudinal central plane of the effective optical area of the IOL, and A4, A6, A8, A10 are coefficient values (see the preceding text of the aspherical surface of the IOL.

(117) TABLE-US-00006 TABLE 6 Ra Rp A4 A6 A8 A10 Preferred embodiment 18.46 11.1 6.46E004 9.86E005 2.19E005 1.12E006 Comparative example 18.46 11.1 1.85E004 2.14E004 3.27E005 1.47E006

(118) It can be seen from Table 6 that the preferred embodiment of the posterior chamber IOL of the present invention and the comparative example in the prior art both have an obviously rearwardly convex surface shape design for the posterior surface of the effective optical area.

(119) It can be further seen from Table 6 that in the preferred embodiment of the posterior chamber IOL of the present invention, the toric surface is at the anterior surface of the effective optical area of the IOL, and all aspherical surfaces are located at the posterior surface of the effective optical area of the IOL; in the comparative example, both the toric surface and the aspherical surface are located at the anterior surface of the effective optical area of the IOL.

(120) FIG. 23 illustratively shows a positional relationship between an intraocular lens axial direction and a maximum refractive power direction of the human cornea when the Toric intraocular lens is implanted into a human eye. When a difference of over 5 is generated between the IOL axial direction and a human eye cornea 11 when the IOL is implanted into the human eye, and the patient's eyesight will be affected seriously. Therefore, an easily recognizable and clear direction marker on the Toric surface is an objective requirement in the surgical procedure for the Toric IOL design. It can be seen that in the preferred embodiment of the posterior chamber IOL of the present invention, it is very favorable that the toric surface is disposed at the anterior surface of the effective optical area of the IOL.

(121) FIG. 24 illustratively shows a MTF contrast diagram of the intraocular lens (preferred embodiment) of the present invention with an aspherical surface and a toric surface being respectively located on both sides and an intraocular lens (comparative example) with the aspherical surface and the toric surface being located on the same side, at a spatial frequency of 0-100 lp/mm in a human eye model with astigmatism and a pupil diameter 3.0 mm.

(122) In FIG. 24, the solid line is MTF curve of an IOL (the preferred embodiment) with the aspherical surface and the Toric surface being respectively located on both sides of the lens at a spatial frequency of 0-100 lp/mm in a human eye model with astigmatism and a pupil diameter 3.0 mm; the dotted line is MTF curve of an IOL (the comparative example) with the aspherical surface and a Toric surface being located on the same side of the lens at a spatial frequency of 0-100 lp/mm in a human eye model with astigmatism and a pupil diameter 3.0 mm. As can be seen from the figure, the MTF curve of an IOL with the aspherical surface and the Toric surface being respectively located on both sides of the lens is higher than the MTF curve of an IOL with the aspherical surface and the Toric surface being located on the same side of the lens, which indicates that under the same condition (at the same astigmatism human eye model, and the aspherical surface coefficients are all optimized), the optical performance of the IOL with the aspherical surface and the Toric surface being respectively located on both sides of the lens is better than the IOL with the aspherical surface and the Toric surface being located on the same side of the lens.

(123) FIG. 25 illustratively shows a wave front chart of a surface shape design of an astigmatism correction IOL of the present invention at an image surface in a human eye model (a preferred embodiment; with the aspherical surface and the toric surface being respectively located on both sides of the IOL); and FIG. 26 illustrates a wave front chart of a surface shape design (a comparative example) in the prior art in the same human eye model with the aspherical surface and the toric surface being combined on one surface in the prior art.

(124) It can be seen by comparing the wavefront aberrations in FIG. 25 and FIG. 26 that the IOL with the toric surface and the aspherical surface separate has a smaller image surface wavefront astigmatism-like fluctuation in an astigmatic eye, with a wavefront aberration PV value being 0.1060, and RMS value being 0.0241; the image surface of the design with the toric surface and the aspherical surface being combined on one surface has an apparent astigmatism-like fluctuation, with a wavefront aberration PV value being 0.3331, and RMS value being 0.0700. Therefore, it is proved that the IOL with the toric surface and the aspherical surface separate has a better astigmatism correction effect for the cornea and a smaller wavefront aberration after correction.

(125) To conclude, as compared with posterior chamber IOL in the prior art, the effective optical area of the posterior chamber IOL of the present invention adopts a design with the posterior surface obviously convex (with a small radius of curvature) and adopts a higher order aspherical surface design or additionally adopts a toric surface design, which reduces the distance between the posterior surface of the effective optical area of the IOL and the posterior capsule, improves stability of a spatial position of the IOL in a capsule bag, gives full play to advantages of the right-angle edge effect of the IOL optical effective area edge, and reduces an incidence rate of posterior capsule opacification (PCO) after implantation of the IOL; since the effective optical area anterior surface is relatively flat, the IOL haptics (particularly with haptics of the one-piece posterior chamber IOL) will not be tightly pressed on the effective optical area anterior surface upon folding, the haptics are more easily unfolded after implantation into the eye and the support haptics are not mutually adhered to the effective optical area, and meanwhile the IOL imaging quality can be improved and/or the visual quality of the astigmatism sufferer is enhanced.

(126) The embodiments described above are only exemplary and not restrictive. Therefore, without departing from the inventive concept disclosed in the description, those skilled in the art may modify or change the above embodiments. Hence, the protection scope of the present invention is only defined by the appended claims.

Posterior chamber intraocular lens

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A61F2/1613

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A61F2/164

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A61F2002/0091

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A61F2002/1699

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Abstract

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