JP3798613B2 - Multifocal lens design method - Google Patents

Description

ただし、（１）式の各符号の意味は下記のとおりとする。
ＰowerDist：パワー分布（単位；Ｄ（ディオプター））
P-Power：レンズ光学部中心点のパワー（単位；Ｄ）
Max-Add：レンズ光学部中心点と最外周点とのパワー差（単位；Ｄ）
Ｂnf：レンズ光学部中心からレンズ遠用度数と近用度数の境界までの距離（単位；ｍｍ）
Ｗave：パワー変化係数（うねり度）
ｘ：レンズ光学部中心点からの距離（単位；ｍｍ）
第３の手段は、
前記P-Power、Max-Add、Ｂnf、Ｗaveの値が下記の範囲であることを特徴とする第２の手段にかかるマルチフォーカルレンズである。
−２５Ｄ≦P-Power≦＋２５Ｄ
−５Ｄ≦Max-Add≦＋５Ｄ
０．５ｍｍ≦Bnf≦３ｍｍ
２≦Ｗave≦１０
第４の手段は、
前記Max-Add、Ｂnf、Ｗaveの値が下記の範囲であることを特徴とする第２又は第３の手段にかかるマルチフォーカルレンズである。
５．００Ｄ≦｜Max-Add｜
１．０ｍｍ≦Bnf≦１．５ｍｍ
４≦Ｗave≦６
第５の手段は、
前記Max-Add、Ｂnf、Ｗaveの値が下記の範囲であることを特徴とする第２又は第３の手段にかかるマルチフォーカルレンズ。
０．２５Ｄ≦｜Max-Add｜≦１．７５Ｄ
１．５ｍｍ≦Bnf≦２ｍｍ
３≦Ｗave≦４
第６の手段は、
前記（１）式並びに下記（２）式及び（３）式において、Ｂnf、Ｗave、中心パワー、周辺パワー、ｃ、ｐ₁、ｐ₂の各値を処方に基づいて決定し、（２）式及び（３）式より、これら式を満すP-Power及びMax-Addの値を求め、（１）式のＰowerDistをｘの関数として決定することを特徴とする第２〜第５のいずれかの手段にかかるマルチフォーカルレンズである。
【数４】

ただし、（２）式（３）式において、中心パワーとは、レンズ光学中心から半径ｃ／２（ｍｍ）の円内の領域に設定される遠用部又は近用部における平均度数であり、周辺パワーとは、光学中心から半径ｐ₁／２（ｍｍ）の円と半径ｐ₂／２（ｍｍ）の円とで囲まれる領域に設定される近用部又は遠用部における平均度数である。また、ｃの範囲は、０．５mm≦ｃ≦３．５ｍｍであり、ｐ₁，ｐ₂の範囲はそれぞれ、２．５ｍｍ≦ｐ₁、ｐ₂≦８ｍｍである。
【０００７】
第１及び第２のの手段において、レンズの度数分布を（１）式のような正接曲線によって定めたことにより、安定した遠用度数領域と近用度数領域を確保することができるとともに、その度数を振動を伴わずに滑らかに変化させることができるようになる。また、各係数を第３の手段の範囲とすることにより、遠用、中用及び近用においてコントラストロスの少ない明瞭な視界が得られるレンズを得ることができる。
また、（１）式の係数を第４の手段の範囲にすることにより、特に遠用及び近用において良好な視界の得られるレンズを得られ、第５の手段の範囲にすることにより、特に、遠用と中用から近用にかけた部分において良好な視界の得られるレンズを得ることができる。
また、第６の手段により、処方値から比較的簡単に（１）式の係数を定めることができ、最適な度数分布を能率よく求めることができる。
【０００８】
【発明の実施の形態】
図１は本発明の第１の実施の形態にかかるマルチフォーカルレンズの説明図である。図１に示すレンズはコンタクトレンズとして構成され、１はレンズ光学部、２は光学部中心、３は周辺のフランジ部をそれぞれ示す。レンズ光学部１は光学部中心２を中心として回転対象形に形成されている。
【０００９】
図２は、図１のＡ−Ａ位置におけるレンズの度数分布状態を示す。
同図において、横軸は光学部中心２からの距離ｘ（ｍｍ）、縦軸は度数ＰowerＤist（Ｄ）を示す。なお、この度数分布は、レンズ光学部１が光学部中心２を中心とする回転対称形に形成されていることにより、Ａ−Ａ位置以外の任意の半径方向にて同じとある。
【００１０】
ここで、同図に示すレンズの度数分布は、上述の（１）式にしたがって定められている。この場合、この（１）式の各係数は、次のようにして定める。すなわ、上述の（１）式、（２）式及び（３）式において、Ｂnf、Ｗave、中心パワー、周辺パワー、ｃ、ｐ₁、ｐ₂の各値は、レンズ装用者の眼の処方から定まる遠用度数や近用度数等によって定まる。したがって、（２）式及び（３）より、これら式を満すP-Power及びMax-Addの値が求められ、（１）式のＰowerDistをｘのみの関数として表すことができる。
【００１１】
図２の度数分布曲線は、（１）式、（２）式及び（３）式において、Ｂnf＝１．２５、Ｗave＝５、中心パワー＝−２．９７（Ｄ）、周辺パワー＝−１．８８（Ｄ）、ｃ＝１．００（ｍｍ）、ｐ₁＝３．００（ｍｍ）、ｐ₂＝３．５（ｍｍ）とし、P-Power＝−３．００（Ｄ）、Max-Add＝＋１．５０（Ｄ）として求めた場合の曲線である。なお、ｃ、ｐ₁、ｐ₂は、次のようにも定義することができる。
ｃ（φmm）：中心パワー領域（"中心遠用-周辺近用"の累進多焦点なら、ｃ遠用部領域）
ｐ₁（φmm）：周辺パワー領域の内径（"中心遠用-周辺近用"の累進多焦点なら、近用部領域の内径）
ｐ₂（φmm）：周辺パワー領域の外径（"中心遠用-周辺近用"の累進多焦点なら、近用部領域の外径）
【００１２】
このレンズでは、中心部に遠用部、周辺部に近用部が配置されているが、同図からもわかるように、安定した遠用度数領域と近用度数領域が確保されている。また、度数は振動伴わずに滑らかに変化している。これにより、遠用と近用の両方にコントラストロスの少ない明瞭な視界を得ることができる。
なお、上記実施形態はコンタクトレンズであるが、眼内レンズ等についても同様の効果を得ることができる。
【００１３】
なお、第１の実施の形態のように、いわゆる遠近用のレンズを構成するには、Max-Add、Ｂnf、Ｗaveの値を下記の範囲内で定めることにより、良好な視界の得られるレンズを得ることができる。
５．００Ｄ≦｜Max-Add｜
１．０ｍｍ≦Bnf≦１．５ｍｍ
４≦Ｗave≦６
【００１４】
図３は本発明の第２の実施形態によるレンズの度数分布状態を示す。この度数分布も上述の第１の実施の形態の場合と同様にして係数を決定した（１）式による分布である。図３の度数分布曲線は、（１）式、（２）式及び（３）式において、Ｂnf＝２．００、Ｗave＝３、中心パワー＝−２．９８（Ｄ）、周辺パワー＝−２．７１（Ｄ）、ｃ＝１．０（ｍｍ）、ｐ₁＝３．０（ｍｍ）、ｐ₂＝４．０（ｍｍ）とし、P-Power＝−３．００（Ｄ）、Max-Add＝＋１．００（Ｄ）として求めた場合の曲線である。
【００１５】
このレンズでは、レンズ中心部の遠用部が広く、加入度数が低くなっている。これにより、このレンズは近用部が中用部（中間距離用）としても用いられ、遠用と中用から近用にかけた部分を重視した度数分布となっている。したがって、まだ老視に至っておらず、近業における調節力としては特に不足はないものの、スポーツ、デスクワーク、ＯＡ作業等の中間位置から近用までの調節力の負担を軽減し、長時間の近業作用によって、眼の疲れを主とした諸症状を軽減するものである。また、比較的遠用光学面が大きく取ってあるため、遠近両用累進多焦点レンズに見られる夜間の光のにじみなども起こりにくいと考えられる。
この実施形態のレンズの場合も、前記実施形態と同様、安定した遠用度数領域と近用度数領域が確保されるとともに、度数が振動を伴わずに滑らかに変化している。
【００１６】
なお、第２の実施の形態のように、遠用と中用から近用にかけた部分を重視した度数分布となったレンズを構成するには、Max-Add、Ｂnf、Ｗaveの値を下記の範囲内で定めることにより、良好な視界の得られるレンズを得ることができる。
０．２５Ｄ≦｜Max-Add｜≦１．７５Ｄ
１．５ｍｍ≦Bnf≦２ｍｍ
３≦Ｗave≦４
【００１７】
図４は本発明の第３の実施形態によるレンズの度数分布状態を示す。この度数分布も上述の第１の実施の形態の場合と同様にして係数を決定した（１）式による分布である。図４の度数分布曲線は、（１）式、（２）式及び（３）式において、Ｂnf＝１．２５、Ｗave＝３、中心パワー＝＋２．９５（Ｄ）、周辺パワー＝＋２．０６（Ｄ）、ｃ＝１．０（ｍｍ）、ｐ₁＝３．０（ｍｍ）、ｐ₂＝３．５（ｍｍ）とし、P-Power＝＋３．００（Ｄ）、Max-Add＝−１．５０（Ｄ）として求めた場合の曲線である。
【００１８】
このレンズでは、レンズ中心部に近用部が形成され、レンズ周辺部に遠用部が形成されている。このように、この実施形態では、上述の第１の実施の形態において、上記（１）式のMax-Addにマイナス符号部をつけることで、遠用部と近用部の配置を逆転させた例である。
【００１９】
図５は本発明の第４の実施形態によるレンズの度数分布状態を示す。この度数分布も上述の第１の実施の形態の場合と同様にして係数を決定した（１）式による分布である。図５の度数分布曲線は、（１）式、（２）式及び（３）式において、Ｂnf＝１．２５、Ｗave＝５、中心パワー＝−３．０Ｄ、周辺パワー＝−１．５Ｄ、ｃ＝０．５ｍｍ、ｐ₁＝３．０ｍｍ、ｐ₂＝４．０ｍｍとし、P-Power＝−３．０５Ｄ、Max-Add＝＋１．９７Ｄとして求めた場合の曲線である。
【００２０】
このレンズはレンズ中心部に遠用部が形成され、レンズ周辺部に近用部が形成されたもので、遠近ではあるが、特に近用での視界を広く確保してる。レンズ中心部に近用部、周辺部に遠用部が配置されるレンズの場合は、上記の場合と逆に、中心パワーを近用度数に、周辺パワーを近用度数に設定する。
【００２１】
なお、（１）式の各係数であるP-Power、Max-Add、Ｂnf、Ｗaveの値を下記の範囲内に設定すれば、遠近レンズや遠用と中用から近用にかけた部分を重視した度数分布となったレンズのいずれのレンズでも良好な視界が得られることが確認されている。
−２５Ｄ≦P-Power≦＋２５Ｄ
−５Ｄ≦Max-Add≦＋５Ｄ
０．５ｍｍ≦Bnf≦３ｍｍ
２≦Ｗave≦１０
【００２２】
次に、種々の処方について、本発明にかかるコンタクトレンズを実際に作製し、装用感をテストした結果を以下に示す。図６は４人の被験者について本発明にかかるコンタクトレンズを装用する前の裸眼又は従来の単焦点コンタクトレンズ（ＣＬ）を装用したときの見え方等を調べた結果を表ー１として示した図である。また、図７は図６の表の４人の被験者について本発明にかかるコンタクトレンズを装用した後の見え方等を調べた結果を示す表ー２として示した図である。さらに、図８は図７の表の４人の被験者が装用した本発明にかかるコンタクトレンズの度数分布を表す（１）式の係数を表ー３として示した図である。
【００２３】
なお、図６〜図８において、「１−Ｒ」は、第１の被験者の右眼、「１−Ｌ」は左眼であり、以下、第２〜第４の被験者も同様である。また、各被験者が装用したレンズは、図７の表ー２にその対応関係を示したとおり、「１−Ｒ」は「Ｎｏ．１」のレンズ、「１−Ｌ」は「Ｎｏ．２」のレンズというように、それぞれ対応する。
【００２４】
図９〜図１２はそれぞれ「Ｎｏ．２」、「Ｎｏ．４」、「Ｎｏ．６」、「Ｎｏ．８」のレンズの度数分布を示す図である。また、図１３〜図１６はそれぞれ「Ｎｏ．２」、「Ｎｏ．４」、「Ｎｏ．６」、「Ｎｏ．８」のレンズの度数分布を立体的に示す図である。
【００２５】
上述の結果から明らかなように、本発明のマルチフォーカルレンズによれば、従来の単焦点レンズに比較して近方及び遠方視力に優れ、かつ、度数の振動を滑らかに変化させることと遠用と中用から近用にかけた部分を重視した度数分布にすることにより、眼の疲れ、痛み、かすみ、羞明、充血、流涙、肩凝り、悪心といった眼精疲労の軽減がみられた。
【００２６】
【発明の効果】
以上説明したように、本発明のマルチフォーカルレンズは、レンズ光学部に遠方を見るための遠用部と近方を見るための近用部が配置される累進多焦点のコンタクトレンズや眼内レンズにおいて、そのレンズの度数分布を正接曲線にしたがって定めることにより、安定した遠用度数領域、中用度数領域及び近用度数領域を確保することができるとともに、その度数を振動を伴わずに滑らかに変化させることができ、これにより、遠用と近用の両方にコントラストロスの少ない明瞭な視界を得ることができる。また、その正接曲線による度数分布の表現は、前述したように、単一の式で比較的簡単に行うことができる。
できる。
【図面の簡単な説明】
【図１】本発明によるマルチフォーカルレンズの第１の実施形態を示す正面図である。
【図２】図１のＡ−Ａ位置におけるレンズの度数分布状態を示すグラフである。
【図３】本発明の第２の実施形態によるレンズの度数分布状態を示すグラフである。
【図４】本発明の第３の実施形態によるレンズの度数分布状態を示すグラフである。
【図５】本発明の第４の実施形態によるレンズの度数分布状態を示すグラフである。
【図６】４人の被験者について本発明にかかるコンタクトレンズを装用する前の裸眼又は従来のコンタクトレンズ（ＣＬ）を装用したときの見え方等を調べた結果を表ー１として示した図である。
【図７】図６の表の４人の被験者について本発明にかかるコンタクトレンズを装用した後の見え方等を調べた結果を示す表ー２として示した図である。
【図８】図７の表の４人の被験者が装用した本発明にかかるコンタクトレンズの度数分布を表す（１）式の係数を表ー３として示した図である。
【図９】「Ｎｏ．２」のレンズの度数分布を示す図である。
【図１０】「Ｎｏ．４」のレンズの度数分布を示す図である。
【図１１】「Ｎｏ．６」のレンズの度数分布を示す図である。
【図１２】「Ｎｏ．８」のレンズの度数分布を示す図である。
【図１３】「Ｎｏ．２」のレンズの度数分布を立体的に示す図である。
【図１４】「Ｎｏ．４」のレンズの度数分布を立体的に示す図である。
【図１５】「Ｎｏ．６」のレンズの度数分布を立体的に示す図である。
【図１６】「Ｎｏ．８」のレンズの度数分布を立体的に示す図である。
【符号の説明】
１ マルチフォーカルレンズのレンズ光学部
２ レンズ光学中心
３ 周辺のフランジ部[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a multifocal lens used as a contact lens, an intraocular lens, and the like, and more particularly, to an effective one when applied to a bilateral presbyopia contact lens or an intraocular lens.
[0002]
[Prior art]
In the multifocal lens, the lens power is distributed so that a distance portion for viewing the distance and a near portion for viewing the near are arranged in one lens optical unit. In the conventional case, the frequency distribution is a low-order function such as a linear function or a quadratic function, or a high-order function as disclosed in, for example, Japanese Patent Application Laid-Open No. 2-240625 and Japanese Patent Application Laid-Open No. 5-181096. It was defined by a polynomial.
[0003]
[Problems to be solved by the invention]
However, low-order functions such as a linear function and a quadratic function have a large rate of change or a rough change state. When the power distribution of the lens is determined by this function, the power of the lens fluctuates greatly and stable distance use is possible. The frequency area and the near-use frequency area cannot be secured. As a result, there arises a problem that stable visual acuity cannot be secured in the distance portion and the near portion.
[0004]
Although a high-order polynomial can secure a stable distance power region and near-power frequency region, a minute vibration is accompanied by a change in the power due to a vibration phenomenon appearing in the high-order polynomial. This results in problems such as increased contrast and loss of field of view.
The present invention has been made in view of the above problems, and its object is to secure a distance power range and a near power range in which the power distribution of the lens is stable and to prevent the power from being accompanied by vibration. An object of the present invention is to provide a multifocal lens that can be changed smoothly and can obtain a clear field of view for both distance and near vision.
[0006]
[Means for Solving the Problems]
As means for solving the above problems, the first means is:
The lens optical unit is provided with a distance portion for viewing the distance, a near portion for viewing the near portion, and a middle portion where the power gradually changes in the region between the distance portion and the near portion. A multi-focal lens such as a contact lens or an intraocular lens, wherein the power distribution of the lens follows a tangent curve.
The second means is
The lens optical unit is provided with a distance portion for viewing the distance, a near portion for viewing the near portion, and a middle portion where the power gradually changes in the region between the distance portion and the near portion. Further, the multifocal lens is a multifocal lens such as a contact lens or an intraocular lens, wherein the power distribution of the lens conforms to the following equation (1).
[Equation 3]

However, the meaning of each symbol in equation (1) is as follows.
PowerDist: Power distribution (unit: D (diopter))
P-Power: Power at the center of the lens optics (unit: D)
Max-Add: Power difference between the lens optics center point and the outermost point (unit: D)
Bnf: Distance from the center of the lens optical unit to the boundary between the lens distance power and near power (unit: mm)
Wave: Power change coefficient (swell degree)
x: Distance from the center of the lens optical unit (unit: mm)
The third means is
The multifocal lens according to the second means, wherein the values of the P-Power, Max-Add, Bnf, and Wave are in the following ranges.
−25D ≦ P-Power ≦ + 25D
-5D ≦ Max-Add ≦ + 5D
0.5mm ≦ Bnf ≦ 3mm
2 ≦ Wave ≦ 10
The fourth means is
The multi-focal lens according to the second or third means, wherein the values of Max-Add, Bnf, and Wave are in the following ranges.
5.00D ≦ | Max-Add |
1.0mm ≦ Bnf ≦ 1.5mm
4 ≦ Wave ≦ 6
The fifth means is
The multi-focal lens according to the second or third means, wherein the values of Max-Add, Bnf, and Wave are in the following ranges.
0.25D ≦ | Max-Add | ≦ 1.75D
1.5mm ≦ Bnf ≦ 2mm
3 ≦ Wave ≦ 4
The sixth means is
In the above formula (1) and the following formulas (2) and (3), values of Bnf, Wave, center power, peripheral power, c, p ₁ and p ₂ are determined based on the prescription, and formula (2) And (3), P-Power and Max-Add values satisfying these expressions are obtained, and PowerDist of expression (1) is determined as a function of x. This is a multifocal lens according to the means.
[Expression 4]

However, in the formula (2) and the formula (3), the center power is an average power in the distance portion or the near portion set in a region within a circle having a radius c / 2 (mm) from the lens optical center, the peripheral power is the average power at the circle and the radius p _2/2 circle the near portion or the distance portion is set in a region surrounded by the (mm) of the radius from the optical center p _1/2 (mm) . The range of c is 0.5 mm ≦ c ≦ 3.5 mm, and the ranges of p ₁ and p ₂ are 2.5 mm ≦ p ₁ and p ₂ ≦ 8 mm, respectively.
[0007]
In the first and second means, the lens power distribution is determined by a tangent curve such as the expression (1), so that a stable distance power region and a near power region can be secured. The frequency can be changed smoothly without vibration. In addition, by setting each coefficient within the range of the third means, it is possible to obtain a lens that can provide a clear field of view with little loss of contrast in distance use, medium use, and near use.
Further, by setting the coefficient of the formula (1) within the range of the fourth means, a lens that can obtain a good field of view in the distance and near use can be obtained, and by setting the coefficient within the range of the fifth means, It is possible to obtain a lens that can provide a good field of view in the part from the distance and the middle to the near.
Further, the sixth means makes it possible to determine the coefficient of the formula (1) relatively easily from the prescription value, so that the optimum frequency distribution can be obtained efficiently.
[0008]
DETAILED DESCRIPTION OF THE INVENTION
FIG. 1 is an explanatory diagram of a multifocal lens according to a first embodiment of the present invention. The lens shown in FIG. 1 is configured as a contact lens. Reference numeral 1 denotes a lens optical part, 2 denotes an optical part center, and 3 denotes a peripheral flange part. The lens optical unit 1 is formed in a shape to be rotated around the optical unit center 2.
[0009]
FIG. 2 shows the power distribution state of the lens at the position AA in FIG.
In the figure, the horizontal axis represents the distance x (mm) from the optical unit center 2 and the vertical axis represents the frequency PowerDist (D). This frequency distribution is the same in any radial direction other than the AA position because the lens optical unit 1 is formed in a rotationally symmetric shape with the optical unit center 2 as the center.
[0010]
Here, the power distribution of the lens shown in the figure is determined according to the above-described equation (1). In this case, each coefficient of the equation (1) is determined as follows. That is, in the above formulas (1), (2), and (3), Bnf, Wave, center power, peripheral power, c, p ₁ , and p ₂ are the prescriptions for the eye of the lens wearer. It is determined by the distance power or near power determined from the above. Therefore, the values of P-Power and Max-Add satisfying these equations are obtained from the equations (2) and (3), and the PowerDist of the equation (1) can be expressed as a function of only x.
[0011]
The frequency distribution curve of FIG. 2 is obtained by using Bnf = 1.25, Wave = 5, center power = -2.97 (D), and peripheral power = −1 in the equations (1), (2), and (3). .88 (D), c = 1.00 (mm), p ₁ = 3.00 (mm), p ₂ = 3.5 (mm), P-Power = −3.00 (D), Max- This curve is obtained when Add = + 1.50 (D). Note that c, p ₁ and p ₂ can also be defined as follows.
c (φ mm): Center power region (if the progressive multifocal of “central distance-periphery”, c distance portion region)
p ₁ (φmm): inner diameter of the peripheral power area (in the case of progressive multifocal for “central distance-periphery”, the inner diameter of the near area)
p ₂ (φmm): Outer diameter of the peripheral power area (if the progressive multifocal of “center distance use-periphery use” is the outer diameter of the near use area)
[0012]
In this lens, the distance portion is disposed at the center and the near portion is disposed at the peripheral portion. As can be seen from the figure, a stable distance power region and a near power region are secured. The frequency changes smoothly without vibration. As a result, it is possible to obtain a clear field of view with little loss of contrast for both distance use and near use.
In addition, although the said embodiment is a contact lens, the same effect can be acquired also about an intraocular lens etc.
[0013]
In order to construct a so-called perspective lens as in the first embodiment, by setting the Max-Add, Bnf, and Wave values within the following ranges, a lens capable of obtaining a good field of view is obtained. Obtainable.
5.00D ≦ | Max-Add |
1.0mm ≦ Bnf ≦ 1.5mm
4 ≦ Wave ≦ 6
[0014]
FIG. 3 shows a power distribution state of a lens according to the second embodiment of the present invention. This frequency distribution is also a distribution according to equation (1) in which the coefficients are determined in the same manner as in the first embodiment. The frequency distribution curve in FIG. 3 is obtained by using Bnf = 2.00, Wave = 3, center power = −2.98 (D), and peripheral power = −2 in the equations (1), (2), and (3). .71 (D), c = 1.0 (mm), p ₁ = 3.0 (mm), p ₂ = 4.0 (mm), P-Power = −3.00 (D), Max- It is a curve at the time of calculating | requiring as Add = + 1.00 (D).
[0015]
In this lens, the distance portion at the center of the lens is wide and the addition power is low. As a result, in this lens, the near portion is also used as the middle portion (for the intermediate distance), and has a power distribution that emphasizes the distance and the portion from the middle portion to the near portion. Therefore, although it has not yet reached presbyopia and there is no particular shortage of adjusting power in near work, it reduces the burden of adjusting power from intermediate positions to near-use for sports, desk work, OA work, etc. It reduces various symptoms, mainly eye fatigue, through business operations. In addition, since the optical surface for far distances is relatively large, it is considered that nighttime light blurs and the like seen in a progressive multifocal lens for both perspectives are unlikely to occur.
Also in the case of the lens of this embodiment, a stable distance power region and a near power region are secured as in the above embodiment, and the power smoothly changes without vibration.
[0016]
As in the second embodiment, in order to construct a lens having a power distribution that places importance on the part from the distance and the middle to the near, the values of Max-Add, Bnf, and Wave are set as follows: By determining within the range, it is possible to obtain a lens with a good field of view.
0.25D ≦ | Max-Add | ≦ 1.75D
1.5mm ≦ Bnf ≦ 2mm
3 ≦ Wave ≦ 4
[0017]
FIG. 4 shows a power distribution state of a lens according to the third embodiment of the present invention. This frequency distribution is also a distribution according to equation (1) in which the coefficients are determined in the same manner as in the first embodiment. The frequency distribution curve of FIG. 4 is obtained by using Bnf = 1.25, Wave = 3, center power = + 2.95 (D), and peripheral power = + 2.06 in the equations (1), (2), and (3). (D), c = 1.0 (mm), p ₁ = 3.0 (mm), p ₂ = 3.5 (mm), P-Power = + 3.00 (D), Max-Add = − It is a curve at the time of calculating | requiring as 1.50 (D).
[0018]
In this lens, a near portion is formed at the center of the lens, and a far portion is formed at the periphery of the lens. Thus, in this embodiment, the arrangement of the distance portion and the near portion is reversed by attaching a minus sign portion to Max-Add in the above formula (1) in the above-described first embodiment. It is an example.
[0019]
FIG. 5 shows a power distribution state of a lens according to the fourth embodiment of the present invention. This frequency distribution is also a distribution according to equation (1) in which the coefficients are determined in the same manner as in the first embodiment. The frequency distribution curve of FIG. 5 is expressed by the following equations (1), (2), and (3): Bnf = 1.25, Wave = 5, center power = −3.0D, peripheral power = −1.5D, It is a curve when c = 0.5 mm, p ₁ = 3.0 mm, p ₂ = 4.0 mm, and P-Power = −3.05D and Max-Add = + 1.97D.
[0020]
This lens has a distance portion formed at the center of the lens and a near portion formed at the periphery of the lens, and although it is far and near, it has a wide field of view especially for near vision. In the case of a lens in which the near portion is disposed at the center of the lens and the far portion is disposed at the periphery, the center power is set to the near power and the peripheral power is set to the near power contrary to the above case.
[0021]
If the values of P-Power, Max-Add, Bnf, and Wave, which are the coefficients in equation (1), are set within the following ranges, focus on the perspective lens and the part from distance to medium to near use. It has been confirmed that a good field of view can be obtained with any lens having a frequency distribution.
−25D ≦ P-Power ≦ + 25D
-5D ≦ Max-Add ≦ + 5D
0.5mm ≦ Bnf ≦ 3mm
2 ≦ Wave ≦ 10
[0022]
Next, the results of actually producing contact lenses according to the present invention and testing the feeling of wearing for various formulations are shown below. FIG. 6 is a table 1 showing the results of examining the appearance, etc. when wearing the naked eye or the conventional single-focus contact lens (CL) before wearing the contact lens according to the present invention for four subjects. It is. FIG. 7 is a view shown as Table 2 showing the results of examining the appearance of the four subjects shown in FIG. 6 after wearing the contact lens according to the present invention. Further, FIG. 8 is a table showing the coefficients of the formula (1) representing the frequency distribution of the contact lens according to the present invention worn by the four subjects in the table of FIG.
[0023]
6 to 8, “1-R” is the right eye of the first subject, “1-L” is the left eye, and the same applies to the second to fourth subjects. In addition, as shown in Table-2 of FIG. 7, the lenses worn by each subject are “No. 1” lenses and “1-L” are “No. 2” as shown in Table-2. This corresponds to each lens.
[0024]
9 to 12 are diagrams showing the frequency distribution of the lenses of “No. 2”, “No. 4”, “No. 6”, and “No. 8”, respectively. 13 to 16 are three-dimensional diagrams showing the power distribution of the lenses of “No. 2”, “No. 4”, “No. 6”, and “No. 8”, respectively.
[0025]
As is clear from the above results, according to the multifocal lens of the present invention, it is superior in near and far vision as compared with the conventional single focus lens, and the vibration of the power is smoothly changed and the distance is reduced. By making the frequency distribution with emphasis on the part from middle to near use, reduction of eye strain such as eye fatigue, pain, haze, lightness, redness, tearing, stiff shoulders, nausea, etc. was observed.
[0026]
【The invention's effect】
As described above, the multifocal lens of the present invention is a progressive multifocal contact lens or intraocular lens in which a distance portion for viewing the distance and a near portion for viewing the near are arranged in the lens optical unit. Therefore, by determining the power distribution of the lens according to the tangent curve, it is possible to secure a stable distance power area, medium power area, and near power area, and smooth the power without vibration. This makes it possible to obtain a clear field of view with little contrast loss for both distance and near vision. In addition, as described above, the expression of the frequency distribution by the tangent curve can be relatively easily performed by a single expression.
it can.
[Brief description of the drawings]
FIG. 1 is a front view showing a first embodiment of a multifocal lens according to the present invention.
FIG. 2 is a graph showing a lens power distribution state at the position AA in FIG. 1;
FIG. 3 is a graph showing a power distribution state of a lens according to a second embodiment of the present invention.
FIG. 4 is a graph showing a power distribution state of a lens according to a third embodiment of the present invention.
FIG. 5 is a graph showing a power distribution state of a lens according to a fourth embodiment of the present invention.
FIG. 6 is a diagram showing the results of examining the appearance of four subjects when wearing the naked eye before wearing the contact lens according to the present invention or the conventional contact lens (CL), etc., as Table 1; is there.
FIG. 7 is a table shown as Table 2 showing the results of examining the appearance and the like after wearing the contact lens according to the present invention for the four subjects in the table of FIG.
FIG. 8 is a diagram showing, as Table-3, the coefficients of the equation (1) representing the frequency distribution of the contact lens according to the present invention worn by the four subjects in the table of FIG.
9 is a diagram showing a power distribution of a lens of “No. 2”. FIG.
10 is a diagram illustrating a frequency distribution of a lens of “No. 4”. FIG.
11 is a diagram illustrating a frequency distribution of a lens of “No. 6”. FIG.
12 is a diagram illustrating a frequency distribution of a lens of “No. 8”. FIG.
FIG. 13 is a diagram three-dimensionally showing the power distribution of the lens of “No. 2”.
FIG. 14 is a diagram three-dimensionally showing the power distribution of the lens of “No. 4”.
FIG. 15 is a diagram three-dimensionally showing a power distribution of a lens of “No. 6”.
16 is a diagram three-dimensionally showing the power distribution of the lens of “No. 8”.
[Explanation of symbols]
1 Lens optical part of multifocal lens 2 Lens optical center 3 Surrounding flange part

Claims (5)

The lens optical unit is provided with a distance portion for viewing the distance, a near portion for viewing the near portion, and a middle portion where the power gradually changes in the region between the distance portion and the near portion. A multifocal lens design method for designing a multifocal lens such as a contact lens or an intraocular lens, wherein a power distribution of the lens is obtained by the following equation (1).

However, the meaning of each symbol in equation (1) is as follows.
PowerDist: Power distribution (unit: D (diopter))
P-Power: Power at the center of the lens optics (unit: D)
Max-Add: Power difference between the lens optical unit center point and the outermost peripheral point (unit: D) Bnf: Distance from the lens optical unit center to the boundary between the lens distance power and near power (unit: mm)
Wave: Coefficient of power change (degree of undulation) x: Distance from the center of the lens optical unit (unit: mm) 2. The multifocal lens design method according to claim 1, wherein the values of P-Power, Max-Add, Bnf, and Wave are in the following ranges.
−25D ≦ P-Power ≦ + 25D
-5D ≦ Max-Add ≦ + 5D
0.5mm ≦ Bnf ≦ 3mm
2 ≦ Wave ≦ 10 3. The multifocal lens design method according to claim 1, wherein the values of Max-Add, Bnf, and Wave are in the following ranges.
5.00D ≦ | Max-Add |
1.0mm ≦ Bnf ≦ 1.5mm
4 ≦ Wave ≦ 6 4. The multi-focal lens design method according to claim 2, wherein the values of Max-Add, Bnf, and Wave are in the following ranges.
0.25D ≦ | Max-Add | ≦ 1.75D
1.5mm ≦ Bnf ≦ 2mm
3 ≦ Wave ≦ 4 In the above formula (1) and the following formulas (2) and (3), values of Bnf, Wave, center power, peripheral power, c, p ₁ and p ₂ are determined based on the prescription, and formula (2) and from equation (3), these equations determine the value of the fully be P-Power and Max-Add, any one of the preceding claims, characterized in that to determine the PowerDist of (1) as a function of x The multifocal lens design method described in 1.

However, in the formula (2) and the formula (3), the center power is an average power in the distance portion or the near portion set in a region within a circle having a radius c / 2 (mm) from the lens optical center, the peripheral power is the average power at the circle and the radius p _2/2 circle the near portion or the distance portion is set in a region surrounded by the (mm) of the radius from the optical center p _1/2 (mm) . The range of c is 0.5 mm ≦ c ≦ 3.5 mm, and the ranges of p ₁ and p ₂ are 2.5 mm ≦ p ₁ and p ₂ ≦ 8 mm, respectively.

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