Contact lens for presbyopia

Abstract

The present invention relates to a contact lens for presbyopia and, more specifically, to a contact lens for presbyopia, providing both a far-distance vision area and a near-distance vision area in one contact lens, and continuously forming a lens magnification of the far-distance vision area and the near-distance vision area of the dominant eye and the non-dominant eye while changing the sizes of the far-distance vision area and the near-distance vision area of two eyes according to the dominant eye and the non-dominant eye, such that an intermediate-distance area is partially overlapped, thereby continuously providing a near-distance vision area at a far distance by a neural summation phenomenon that selects a clearly visible image in both eyes.

Claims

1. A contact lens for presbyopia, which has a far-distance part having a far-distance refractive index, and a near-distance part having a near-distance refractive index, both of which are respectively formed in divided areas of the contact lens, comprising; a central area configured as a far-distance refractive index and providing a main visual field, the central area including a constant diameter of 1.6 millimeters; a finish area having a ring shape and formed along an edge of the contact lens; an optical area formed between the central area and the finish area and having refractive power so as to provide a vision area, wherein the optical area divides the far-distance part that is an upper area and the near-distance part that is a lower area, and a transition part with a certain width is formed at a boundary between the far-distance part and the near-distance part, the transition part extending from the finish area to the central area, wherein the far-distance part and the near-distance part has a sector shape with a certain angle, respectively, and are divided in relation to the transition part, wherein in instances in which the optical area is a dominant eye, the far-distance part and near-distance part form refractive indices respectively in a 90-210 degree range and a 90-150 degree range so as to be symmetrical in a left-right direction, and in instances in which the optical area is a non-dominant eye, the far-distance part and near-distance part provide refractive indices respectively in a 90-150 degree range and a 90-210 degree range so as to be symmetrical in a left-right direction, and the transition part is in a range of 3 to 7 degrees, wherein in instances in which the optical area is the dominant eye, an intended refractive index of the far-distance part is configured as emmetropia, an intended refractive index of the near-distance part of the dominant eye is configured as −0.75 D (diopter); and in instances in which the optical area is the non-dominant eye, an intended refractive index of the far-distance part is configured as −0.50 D, an intended refractive index of the near-distance part of the non-dominant eye is configured as −2.25 D.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 is a plane view of a contact lens for presbyopia according to an embodiment of the present invention.

(2) FIG. 2 is a plane view of a modifiable area of a boundary of a far-distance part and a near-distance part in terms of a contact lens for presbyopia according to an embodiment of the present invention.

(3) FIGS. 3a and 3b are sectional views of a usual single focus lens.

(4) FIG. 3c is a schematic view of a vision range of a traditional contact lens for presbyopia such as a single focus lens, a bifocal lens, or a multi focus lens.

(5) FIGS. 4a and 4b are sectional views of a contact lens for presbyopia of the present invention, and a schematic view of a vision range of a contact lens for presbyopia of the present invention.

(6) FIGS. 5a to 5d are plane views of modified examples of a contact lens for presbyopia of the present invention according to various angles.

(7) FIG. 6a is a graph of defocus of both eyes, which illustrates improved visual acuity at all distances according to a preferred embodiment of the present invention.

(8) FIGS. 6b and 6c are graphs of defocus of both eyes on which a traditional multi focus lens and a traditional single focus lens are worn.

BEST MODE FOR CARRYING OUT THE INVENTION

(9) The present invention will be described in detail with reference to the attached drawings. However, the attached drawings will be provided only as examples to easily describe the technical spirit and scope of the present invention and are not intended to limit or modify the technical scope of the present invention. Further, it is apparent to those skilled in the art to which the present invention pertains that the present invention may be modified and changed in various forms on the basis of the examples without departing from the scope of the technical spirit of the present invention.

(10) FIG. 1 is a plane view of a contact lens for presbyopia according to an embodiment of the present invention.

(11) A contact lens for presbyopia 10 according to the present invention is configured to contact the cornea of a user who wears the contact lens, and an inner surface of the contact lens for presbyopia is configured to correspond to the surface of the cornea of the user.

(12) The contact lens has a circular shape with a total diameter of 12.6 mm or so, and the inner surface of the contact lens is curved.

(13) The contact lens 10 is divided into three areas: a central area 20 where a pupil is positioned, a finish area 30 which is formed at an edge of the contact lens, and an optical area 40 which is interposed between the central area and finish area and where a refractive index is formed.

(14) The central area 20 is configured to have a diameter of 1.5 to 1.7 mm and have a far-distance refractive index that is a major visual field. Preferably, the central area has a constant diameter of 1.6 mm such that eyes easily adapt at the time when contact lenses are replaced.

(15) Further, the finish area 30 is configured to have a ring shape, is formed at the edge of the contact lens, is configured to have a width of 1.3 mm or so, and is configured to have an aspheric surface such that a wearer feels no discomfort.

(16) Further, the optical area 40 has a diameter of 10.0 mm or so and corresponds to an area excluding the central area. The optical area 40 forms different refractive indices and includes a far distance part 41 used to see distant objects and a near-distance part 42 used to see close objects. In this case, preferably, the far-distance part 41 is connected with the central area 20 and formed at an upper area of the optical area while the near-distance part 42 is formed at a lower area of the optical area.

(17) Additionally, a transition part 43 is further formed between the far-distance part 41 and the near-distance part 42 in the optical area 40 so as to alleviate differences in thickness caused by different refractive indices.

(18) In the optical area, the far-distance part 41, the near-distance part 42, and the transition part 43 may be divided in an up-down direction on the basis of a horizontal line, in a left-right direction on the basis of a vertical line or in various ways. However, the optical area is preferably divided into sectors according to a certain angle on the basis of the center of a circle.

(19) For instance, the far-distance part 41 that is an upper area, and the near-distance part 42 that is a lower area are divided in an up-down direction on the basis of a horizontal line, and similarly have an angle of 180 degrees, and a sector-shaped transition part 43 with a central angle of 5 degrees or so is formed between the far-distance part and the near-distance part so as to alleviates difference in refractive indices, as illustrated in FIG. 1.

(20) Additionally, as illustrated in FIG. 2, when a central angle of a sector of the far-distance part 41 increases or decreases, and a central angle of a sector of the near-distance part 42 increases or decreases, areas of the far-distance part and the near-distance part, which are symmetrical in a left-right direction and asymmetrical in an up-down direction, may be formed. That is, if far-distance sight is usually used, a sector area of the far-distance part increases so as to expand a scope for providing far-distance sight, and if near-distance sight is usually used, a sector area of the near-distance part increases so as to expand a scope for providing near-distance sight.

(21) As described above, when it comes to the optical area 40, the far-distance part 41 and the near-distance part 42 provides a far-distance refractive index or a near-distance refractive index in the range of a central angle of a sector of 90 to 270 degrees. The transition part 43 between the far-distance part and the near-distance part forms a central angle of a sector in the range of 3 to 7° degrees diplopia so as to minimize frequency of side effects such as double vision, lunar halos, light sensitivity.

(22) The expansion of the far-distance part 41 leads to expansion of the range of vision when things at a far distance are seen. Accordingly, if the far-distance part of a lens is expanded, the quality of sight with respect to a wide range may be improved. On the contrary, even when the angle of the near-distance part of a lens is reduced, this causes little discomfort in sight because the near-distance part 42 provides a narrow range of vision. That is, various central angles of sectors of the far-distance part and the near-distance part of a contact lens may be formed depending on the ranges in which things are seen.

(23) Meanwhile, a contact lens 10 of the present invention may form different far-distance and near-distance refractive indices between both eyes. That is, eyes are divided into two. An eye that is usually used (an eye that can clearly see things) is a dominant eye while the other eye is a non-dominant eye. Then refractive indices of a far-distance part and a near-distance part are configured to be different with respect to the dominant and non-dominant eyes. To test a dominant eye, both eyes are opened, both hands are placed in front of a face and form a triangle, and an object at a far distance is gradually placed in the middle of the triangle. When each eye is covered, the eye where the object is placed in the triangle is a dominant one.

(24) For instance, in terms of refractive indices in the optical area at the time of wearing the lens, the far-distance part of a dominant eye is configured as 0 D that is emmetropia; the near-distance part of a dominant eye is configured as −0.75 D; the far-distance part of a non-dominant eye is configured as −0.50 D; the near-distance part of a non-dominant eye is configured as −2.25 D. Thus, a blend zone, where both eyes have common refractive indices ranging from −0.50 D to −0.75 D, may be formed.

(25) FIG. 3a is a view of a usual far-distance single focus lens 50. As illustrated in FIG. 3a, focal length with respect to a far distance is configured to be short. FIG. 3b is a view of a usual near-distance single focus lens 60. As illustrated in FIG. 3b, focal length with respect to a near distance is configured to be short. If a mono vision method in which both eyes have different refractive indices with such a single focus lens is applied, focal depths of a far distance and a near distance are short, as illustrated in FIG. 3c. Thus, an intermediate distance 70 between the focal depths of a far distance and a near distance is out of focus, and a blurred zone where an image formed on the eye is blurred is created, thereby dropping visual acuity of both eyes.

(26) Certainly, a far-distance part and a near-distance part are formed on one lens, and a transition part is formed between the far-distance part and the near-distance part so as to prevent a rapid change in a refractive index. However, it is hard for the transition part to provide good sight, a section of the transition part is simultaneously formed at a portion of the intermediate distance in both eyes, and phenomena such as double vision, lunar halos or light sensitivity takes place. Thus, it is hard to provide continuous sight according to a focus.

(27) According to a contact lens for presbyopia 10 of the present invention, as illustrated in FIG. 4a, a far-distance part 41 and a near-distance part 42 are arranged in an up-down direction, refractive indices of the far-distance part and near-distance part are formed within a certain range, and an integrated focal depth increases such that visual acuity at an intermediate distance is improved.

(28) If the focal depth increases, continuous sight may be provided from a far distance to a near distance at the time of providing different refractive indices in both eyes.

(29) That is, if a different range of refractive indices, as illustrated in FIG. 4b, is formed for a dominant eye and a non-dominant eye at the time of wearing a lens. A blend zone, where a focal depth or a refractive index becomes identical at an intermediate distance 70 of the dominant eye and non-dominant eye, is created because of an increased focal depth. Thus, intermediate-distance visual acuity may be improved.

(30) A far-distance contact lens and a near-distance contact lens worn on both eyes are configured to have a different range of refractive indices using a contact lens for presbyopia, whose focal depth is increased, and differences in the degrees of the far-distance and near-distance contact lenses are configured to be small. Thus, a blend zone, which is an intermediate distance 70 at which sizes of the images formed on both eyes become identical, exists, such that sizes of the images formed on both eyes become identical and intermediate-distance visual acuity is improved through the blend zone.

(31) Additionally, there is a difference in clarity of the image formed on the eyes at a far distance and a near distance excluding an intermediate distance, but sizes of multiple images do not look largely different, and only a clear image is selected and recognized through an innate binocular neural adaption system. Thus, clear sight may be obtained. That is, when two images are formed on both eyes that are binocular neural adaptation systems, the neural gate instantly selects a clearer image so as to obtain the most effective recognition. Therefore, clear sight may be provided in all areas from a far distance to a near distance because a clear image may be obtained at a far distance and at a near distance in addition to a blend zone, and visual acuity is improved.

(32) When the far-distance part and the near-distance part of both eyes are configured to have different refractive indices, central angles of the sectors of the far-distance part 41 and the near-distance part 42 of both eyes, as illustrated on the left side of FIG. 5a, are configured to be close to 180 degrees so as to have an identical proportion in an up-down direction.

(33) Additionally, in the case of a dominant eye that usually provides far-distance sight, as illustrated in FIG. 5b, a central angle of the sector of the far-distance part 41 at an upper portion is increased while a central angle of the sector of the near-distance part 42 at a lower portion is decreased. In the case of a non-dominant eye that usually provides near-distance sight, as illustrated on the right side of FIG. 5b, a central angle of the sector of the far-distance part 41 at an upper portion is decreased while a central angle of the sector of the near-distance part 42 at a lower portion is increased. Preferably, central angles of the sectors of the far-distance part and near-distance part of a dominant eye are respectively configured to be 210 degrees and 150 degrees while central angles of the sectors of the far-distance part and near-distance part of a non-dominant eye are respectively configured to be 150 degrees and 210 degrees.

(34) Additionally, in the case of a dominant eye, the far-distance part 41, as illustrated on the left side of FIG. 5c, may be expanded as much as possible while in the case of a non-dominant eye, the near-distance part 42, as illustrated on the right side of FIG. 5c, may be expanded as much as possible. Preferably, central angles of the sectors of the far-distance part and near-distance part of a dominant eye are respectively configured to be 270 degrees and 90 degrees while central angles of the sectors of the far-distance part and near-distance part of a non-dominant eye are respectively configured to be 90 degrees and 270 degrees.

(35) Further, various angles ranging from 180 degrees to 270 degrees, as illustrated in FIG. 5d, are provided such that visual acuity is improved. Preferably, angles of the far-distance part and near-distance part of a dominant eye are respectively configured to be 240 degrees and 120 degrees while angles of the far-distance part and near-distance part of a non-dominant eye are respectively configured to be 120 degrees and 240 degrees.

(36) Most preferably, as illustrated in FIG. 5b, the far-distance part and near-distance part of a dominant eye form refractive indices respectively in a 210 degree range and a 150 degree range so as to be symmetrical in a left-right direction, the far-distance part and near-distance part of a non-dominant eye provide refractive indices respectively in a 150 degree range and a 210 degree range so as to be symmetrical in a left-right direction, and the transition part alleviates differences in thickness in a range of 3 to 7 degrees.

(37) According to the present invention, the far-distance parts 41 and near-distance parts 42 of two contact lenses worn on both eyes are configured to be asymmetrical to each other. Thus, both eyes have different refractive indices in some sections. However, differences in the degrees of the far-distance part and near-distance part in each contact lens are configured to be small, focal depths of the far-distance part and near-distance part in each contact lens are continuously arranged such that an integrated focal depth is increased, a section where focal depths of both eyes become identical is created at an intermediate distance, vision of both eyes is improved, and visual acuity at the intermediate distance is improved. Additionally, if any one of both eyes is out of a focal depth, and a blurred image is provided, a clear image of the two images formed on both eyes is selected and recognized through a binocular neural adaption system. Thus, clear sight may be provided at a far distance, at an intermediate distance, and at a near distance.

(38) FIG. 6a is a graph of defocus of vision of both eyes on which contact lenses of the present invention, manufactured in a range the same as that in FIG. 5b, are worn. As illustrated, good eyesight is provided at a far distance, and balanced eyesight is also provided at an intermediate distance and a near distance. Thus, focus is formed at most distances, and balanced and natural eyesight is formed.

(39) FIGS. 6b and 6c are graphs of defocus of vision of both eyes on which a traditional multi focus lens for presbyopia and single focus lens for presbyopia are worn. As illustrated, visual acuity rapidly drops at an intermediate distance.

(40) Intermediate-distance sight of the present invention is better than that of a traditional method, and width in sight is narrowed in an entire area, such that a wearer easily adapts.

(41) Experiment 1) Comparison of Visual Acuity with Respect to a Refractive Index

(42) Visual acuity is measured with respect various refractive indices of a contact lens.

(43) According to Embodiment 1, both eyes are divided into a dominant eye and a non-dominant eye. An optical area of the contact lens is configured to be in a 180 degree angle, is divided into a far-distance part at an upper portion and a near-distance part at a lower portion in an up-down direction, and is configured to have refractive indices listed in Table 1.

(44) In Comparative example 1, the left and right eyes all have the same refractive index, and a multi focus lens with a far distance at the center, a near distance at the edge, and an intermediate distance between the center and the edge have the refractive indices listed in Table 1.

(45) In Comparative example 2, the left and right eyes all have the same refractive index, and a multi focus lens with a far distance at the center and a near distance at the edge, have the refractive indices listed in Table 1.

(46) In Comparative example 3, both eyes are divided into a dominant eye and a non-dominant eye, and a one-eye contact lens in which only refractive indices of both eyes are different is configured to have refractive indices listed in Table 1.

(47) TABLE-US-00001 TABLE 1 Dominant eye Non-dominant eye Far Intermediate Near Far Intermediate Near distance distance distance distance distance distance Embodiment 1 0.00 — −0.75 −0.50 — −2.25 Comparative 0.00 −1.50 −3.00 0.00 −1.50 3.00 example 1 Comparative 0.00 — −2.50 0.00 — −2.50 example 2 Comparative 0.00 — — — — −2.50 example 3

(48) Near-distance vision (Jaeger method), intermediate-distance vision (decimal method), and far-distance vision (decimal method) of 20 patients with presbyopia in their fifties are measured using contact lenses having refractive indices listed in Table 1, three-dimensional effects and degrees of adaptation are expressed in five grades ranging from the lowest to the highest, the question of whether there is a blurred area or not is checked, and an average value is listed in Table 2.

(49) TABLE-US-00002 TABLE 2 Three- Near- Intermediate- dimensional Degree of distance distance Far-distance effect Blurred adaptation vision vision vision (1~5) area (1~5) Embodiment 1 J2 1.0 1.0 4 x 6 Comparative J2 0.8 1.0 2 ∘ 2 example 1 Comparative J2 0.1 1.0 1 ∘ 2 example 2 Comparative J2 0.1 1.0 1 ∘ 2 example 3

(50) As in Table 2, Embodiment 1 shows good results in terms of intermediate-distance vision, a three-dimensional effect, and a degree of adaptation. Additionally, when it comes to Embodiment 1, there is no blurred area. As a result, a clear image is provided in the entire vision area.

(51) Comparative example 1 shows improved intermediate-distance vision. However, Comparative examples 1 to 3 show that there is a blurred area due to a refractive index vacuum area on both eyes and that there is a refractive index vacuum area. Additionally, Comparative examples 1 to 3 show a low grade in terms of a three-dimensional effect and a degree of adaptation.

(52) Experiment 2) Comparison of Visual Acuity with Respect to the Scopes of a Far Distance and a Near Distance

(53) In the optical area of the contact lens, angles of formation of a far distance part and a near distance part with respect to a dominant eye and a non-dominant eye are set as listed in Table 3. In this case, the angels are symmetrical in a left-right direction on the basis of a vertical line passing through the center, and the refractive indices of the dominant eye and non-dominant eye is set as listed in Embodiment 1. Embodiment 2 is manufactured as in FIG. 5b, Comparative example 4 as in FIG. 5a, Comparative example 5 as in FIG. 5c, and Comparative example 6 as in FIG. 5d.

(54) TABLE-US-00003 TABLE 3 Dominant eye Far- Non-dominant eye distance Near-distance Far-distance Near-distance (angle) (angle) (angle) (angle) Embodiment 2 210 150 150 210 Comparative 180 180 180 108 example 4 Comparative 270 90 90 270 example 5 Comparative 240 120 120 240 example 6

(55) Near-distance vision (Jaeger method), intermediate-distance vision (decimal method), and far-distance vision (decimal method) of 20 patients with presbyopia in their fifties are measured using contact lenses having angles listed in Table 3, three-dimensional effects and degrees of adaptation are expressed in five grades ranging from the lowest to the highest, and an average value is listed in Table 4.

(56) TABLE-US-00004 TABLE 4 Three- Near- Intermediate- Far- dimensional Degree of distance distance distance effect adaptation vision vision vision (1~5) (1~5) Embodiment J2 1.0 1.0 4 5 2 Comparative J3 1.0 0.8 4 5 example 4 Comparative J2 0.8 1.0 2 2 example 5 Comparative J2 0.8 1.0 3 3 example 6

(57) As listed in Table 4, Comparative example 4, where a far-distance part and a near-distance part are divided at an identical angel, shows worse near-distance vision and far-distance vision than Embodiment 2.

(58) Further, Comparative examples 5 and 6, where a far-distance angle of the dominant eye and a near-distance angle of the non-dominant eye increase, show grades lower than Embodiment 2 in terms of intermediate-distance vision, three-dimensional effects and degrees of adaptation.

(59) As a result, when the refractive indices of a far distance and a near distance are formed in an angle range of Embodiment 2, the best quality of vision may be obtained.