JPH03109522A - Progressive multifocus lens - Google Patents

Abstract

PURPOSE:To obtain the progressive multifocus lens optimum for using in an active condition by specifying the length of the main meridian included in an intermediate part region to >=18mm and specifying the max. gradient of a change in the refractive power on the main meridian in the intermediate region. CONSTITUTION:The projecting face side refracting face of, for example, the progressive multifocus lens has the far vision part region 1, the intermediate part region 2, the near vision part region 3 and the main meridian M. The change in the refracting power on the main meridian M is so set that the refracting power upper than the point A is 6.0D (dioptry), the refracting power below the point B is 8.0D and the refracting power increases nearly linearly from the point A to the point B exclusive of the parts near the respective points. Namely, the refracting power D1 of the far vision part region is 6.0D and the refracting power D2 of the near vision part region is 8.0D. The distance between the point A and the point B, i.e. the length L of the progressive zone is 20mm(>=18mm). The max. gradient of the change in the refracting power on the main meridian M is 0.10D/mm. The progressive focus lens is particularly suitable for applications to sports, such as golfing, and going out for the purpose of driving of cars, shopping, etc.

Description

[Detailed description of the invention] The present invention relates to the shape of a refractive surface of a progressive multifocal lens.

The purpose of the present invention is to
Another object of the present invention is to provide a progressive multifocal lens that is optimal for use in active situations such as when playing sports.

Progressive multifocal lenses were developed to correct the decline in the accommodative function of the crystalline lens of the eye in the elderly.Currently, various types of lenses are commercialized, but all have the same basic configuration. It's the same. In other words, a progressive multifocal lens has an area for seeing distant objects and an area for seeing near objects at the top and bottom of the lens, and there is a continuous area between the two areas. It has a refractive power that changes over time, and has an area for seeing objects at intermediate distances.
It is called the intermediate region, and is divided into left and right parts by the principal meridian that runs in the vertical direction. A lens has two refractive surfaces, a convex surface and a concave surface, and the refractive surface having each of the above regions is usually formed so that there is no visible boundary line on the convex surface side, and in this case, the concave surface side is a spherical or toric surface, Corrects farsightedness, nearsightedness, and astigmatism. FIG. 1 shows the convex refractive surface of the material lens 10 of such a conventional progressive multifocal lens, and shows the arrangement of each region. 1.2.3 are the continuous use region, intermediate region, and near vision region, respectively, and M is the principal meridian. In Figure 1, point A is the geometric center of this lens,
It is also optically centered. Therefore, in boat fishing, point A is called the center of distance vision, and point B is called the center of near vision. FIG. 2 shows changes in refractive power along the principal meridian M. Above point A, that is, within the distance region, the refractive power on the principal meridian M is constant (day tree), and below point B,
That is, within the near vision area, D2 (day tree) is constant. From point A to point B, the refractive power gradually increases from Dl to D2. The difference between the refractive powers D1 and D2 is
It is called the addition power and is usually between 0.5 diopters and 3.
The distance between point A and point B in the 0 diagram, which is within the range of 5 diopters, is called the length of the intermediate portion or the length of the progressive zone. In order to make these parts with different refractive powers into one smooth curved surface, a progressive multifocal lens has to be made into an aspherical surface, which results in astigmatism occurring at the lens periphery. Further, since the magnification of the image changes at each part of the refractive surface, image distortion also occurs. These are shown in FIGS. 3 and 4.

FIG. 3 is an isoastigmatism diagram showing the distribution of astigmatism.

In the figure, the narrower the hatching pitch, the greater the astigmatism, which means that the image becomes blurred. Generally, it is said that people perceive astigmatism and feel discomfort when it is 0.5 diopters (hereinafter abbreviated as D) or more, but if you do not stare at things that much, 0.5 to 1.0D can also be used. In the figure,
The non-hatched area has astigmatism 1. This is an area below OD.

The principal meridian M is usually an origin curve. The origin curve is a series of points having the same principal radius of curvature, that is, a series of minute spherical surfaces, and astigmatism is zero on this line.

FIG. 4 shows the distortion of an image when a square grid is viewed through a lens. In the image of a square lattice, due to the change in magnification, as shown in the figure, the vertical lines bulge downwards centering on the one passing through the principal meridian (41 in the figure), and the horizontal lines also curve toward the periphery. This image distortion is not only perceived as image distortion, but also occurs when the visible object moves relative to the user's line of sight, such as when the user follows a moving object with their eyes or moves their neck. The shaking of the statue caused a great deal of discomfort. Cases in which we see moving objects in this way are called dynamic vision, whereas cases in which there is almost no movement of the line of sight and objects, such as when reading a book or gazing at a point, are called static vision. As is clear from the above explanation, static vision is primarily affected by astigmatism. In other words, the smaller the astigmatism as a whole, the smaller the region of small astigmatism (
For example, the wider the area (area of 1.0D or less), the more comfortable vision can be obtained. On the other hand, dynamic vision is mainly affected by image distortion. In other words, the smaller the image distortion,
Provides comfortable vision. The relationship between static vision and dynamic vision is not independent; if you widen the area with small astigmatism to obtain good static vision, the image magnification will increase around that area, that is, on the side of the lens. Because the change becomes rapid, the image distortion becomes thicker (which impairs dynamic vision; conversely, improving dynamic vision narrows the areas with small astigmatism in the operating and near vision areas). They have a contradictory relationship, as they harm static vision.

Furthermore, more generally, it can be said that improving one characteristic will adversely affect another characteristic. Therefore, when designing progressive multifocal lenses, it has been said that it is important to consider the balance between static vision and dynamic vision. There are many different designs of progressive multifocal lenses, and this is due to the different emphasis placed on both static and dynamic vision. With emphasis on this, the operation area is entirely spherical, and the near vision area also has a wide spherical part in the center. Therefore, although static vision is good, dynamic vision is impaired due to large image distortions in the intermediate region and the lateral portions of the near region. Another lens emphasizes dynamic vision and has an aspheric surface based on the tilted distance area and the near vision area in order to reduce image distortion overall. Therefore,
The small area of astigmatism is narrowed and static vision is impaired. However, despite these differences, there is a common basic concept in the design of conventional progressive multifocal lenses. The aim is to create a single progressive multifocal lens eyeglass that can be used in all situations, that is, to design a universal progressive multifocal lens.

Therefore, in some cases it can be very inconvenient. For example, when playing sports (such as golf), when going out for shopping, or when driving a car. As mentioned above, the desired characteristics of a progressive multifocal lens used in such situations cannot be obtained from a general-purpose lens designed simply for static vision or dynamic vision. Until now, there have been no progressive multifocal lenses that are suitable for use in the above situations. However, although some types of low-addition lenses were partially suitable (which is natural since they can reduce aberrations),
Some of the lenses with medium or higher add power, which require a progressive multifocal lens, are suitable (but not all). By slightly changing the conventional way of thinking, we emphasize both static and dynamic vision in the operational and intermediate regions, and emphasize both static and dynamic vision to some extent in the near vision region. We will explain this in detail. First, in the area of continuous use, even when you turn your eyes to the side with your face facing forward, there will be no blurring or blurring of the image. It is desirable that there is almost no distortion or shaking.It is even better if this is true not only directly to the side, but also to the sides slightly diagonally below the horizontal (the diagonally below part can be considered as the middle area of the lens, but it is preferable (There is no difference in the characteristics of the distance.) When swinging golf, a wide distance field of view with little vibration is essential, and when driving a car, the wider the field of view without blurring or distortion, the better.

Next, regarding the middle area, it is desirable that the range where the image can be seen without blurring is wide, and that image distortion and shaking are small in the side areas. This middle area plays a particularly important role when reading the display on the instrument panel, the prices of items in a shop window, and labels when shopping. Finally, regarding the near vision area,
The width of the area where the image can be seen without blurring should be kept to the minimum necessary. Of course, it is better to have a wider width, but this should be sacrificed in order to improve the characteristics of the distance and intermediate regions. This is because the near vision area does not play such a major role when used for golfing, driving, shopping, etc. and is rarely used for long periods of time. For example, in the case of golf, as long as you can keep score, you can achieve the general purpose.

None of the conventional progressive multifocal lenses have the above-mentioned favorable characteristics.

This will be explained with reference to FIG. 3 and the like. First, it is necessary to consider how to process the progressive multifocal lens 10, which is in the form of a circular material lens as shown in FIG. 3, into eyeglasses. One is where to set the fitting point. The fitting point is the point where the eyeglass wearer
This is the position where the line of sight passes over the lens when looking into the distance in a normal (relaxed) posture, and is sometimes called the eye point. Generally, point A on the principal meridian M and 2 points above it
The point is set somewhere between ~3 mm. In FIG. 3, fitting point F is set on point A. Another method is to take into account convergence (when looking at something close up, the line of sight comes closer to the inside than when looking far away), and make the distance between points B of the left and right lenses shorter than the distance between points A of the left and right lenses. It is the right thing to do. Generally, a lens that is bilaterally symmetrical about the principal meridian M as shown in FIG. 3 is used by rotating the lens by about 10 degrees. That is, in FIG. 3, H' is the horizontal line when worn, and 11 is the shape of the eyeglass lens after processing. Now, regarding the characteristics of conventional progressive multifocal lenses,
Since there is a large difference depending on the addition power, the case where the addition power is 2.0D will be explained. Note that the progressive multifocal lenses currently in practical use are based on measurement results using a lens meter with an aperture diameter of 5 mm. First, the characteristics of the distance region are astigmatism 1. It is evaluated by the position of the isoastigmatism line of OD. In a bilaterally symmetrical lens as shown in FIG. 3, the isoastigmatism line is generally 0 to 10 degrees above the horizontal line H. However, when actually processing the glasses, the lenses are rotated by about 10 degrees to take convergence into account, so the lenses are rotated 10 to 20 degrees above the horizontal line H' when worn. (This is the case for the door side (left side of Figure 3).) In this case, the image becomes blurred when viewed horizontally and laterally, making it difficult to use.It also prevents the line of astigmatism 1.0D from rising due to rotation of the lens. For this purpose, there is also a progressive multifocal lens that bends the principal meridian M to make it asymmetrical, as shown in Figure 5.
Even in this type, the line of astigmatism 1.0D is generally located 0 to 10 degrees above the horizontal line when worn. Although it has been improved somewhat, it is still difficult to use. Another disadvantage of this type of lens is that astigmatism, image distortion, and shaking become large from the lower distance region to the upper intermediate region on the door side (left side in FIG. 5). Note that this drawback also exists in lenses that are bilaterally symmetrical and place emphasis on static visual field (for example, lenses that have a spherical surface above the horizontal line H). Next, the characteristics of the intermediate region are astigmatism 1. Evaluation is based on the minimum width S of the area within OD.

In conventional progressive multifocal lenses, this minimum width S is 3 to 8 m.
m, and many of them are particularly 5 to 6 mm. If we consider the width of S to make it easier to use, let's take the example of looking at an object at arm's length (for example, looking at the instrument panel when driving a car). 20
It is convenient to be able to see a width of ~30 cm; converting this to the width of an S is about 8 to 12 mm, and all conventional ones are too narrow.

-Iillll, the minimum width S is approximately determined by the length of the progressive zone and the refractive power change gradient on the principal meridian, and the longer L and the gentler the gradient, the wider S becomes. Therefore, it can be said that all conventional lenses have short progressive zone lengths. This is because all conventional lenses aim to be general-purpose lenses. That is, if the length of the progressive zone is long, it is necessary to turn the line of sight significantly downward when using the near vision area. This makes near vision difficult, so the length of the progressive zone could not be made very long as a general-purpose lens.

The length of the progressive zone of conventional lenses is 10 to 16 mm, but 16 mm is sometimes said to be too long. From the perspective of the maximum gradient of refractive power change, it is 0.20 to 0.1.
3D/mm.

The shorter the length of the progressive zone and the steeper the gradient, the greater the astigmatism, image distortion, and shaking in the lateral portions of the intermediate region, making it difficult to use. Finally, the characteristics of the near vision area are astigmatism 1. The evaluation is based on the maximum width W of the area within OD. In conventional progressive multifocal lenses, this maximum width W is often around 20 mm, but some of them exceed 30 mm. If this maximum width W is increased, it will have an adverse effect not only on the lateral parts of the near region but also on the lateral parts of the intermediate region, increasing astigmatism and increasing image distortion and shaking. Further, the 1, 0D isoastigmatism line explained in connection with the continuous portion region is pushed upward. Further, this maximum width W is generally much wider than the minimum width S of the intermediate region. The ratio of the maximum width W to the minimum width S is 2 to 3 times as small as 7 to 8 times as large. This difference in width between the two causes a large distortion at the side portion 42 at point B shown in FIG. 4, which causes significant discomfort to the wearer.

Now, for the purpose we are considering here, it would be sufficient to be able to see the width of one page of a book (approximately 15 cm wide at a distance of about 30 cm). Then, since the maximum width W may be 15 mm or less, all conventional progressive multifocal lenses can be said to be quite wide.

The present invention improves the drawbacks of the conventional progressive multifocal lens described above, especially lenses with medium or higher addition power, and dramatically improves the visibility of the operation area and the intermediate area, It also thoroughly eliminates the image distortion and shaking that the wearer feels.

As a result, the progressive multifocal lens according to the present invention is particularly suitable for sports such as golf, driving a car, going out for shopping, and the like.

The present invention will be explained in detail below using examples.

First, an example in which the addition power is 2.0D will be described.

FIG. 6 shows the convex refractive surface of the progressive multifocal lens of the present invention, and 1.2.3 are the active region, the intermediate region, and the refractive surface, respectively.
Near region, M is the principal meridian. FIG. 7 shows the change in refractive power along the principal meridian M. The refractive power above point A is 6.
The refractive power below point OD and B is 8.0D, and increases almost linearly from point A to point B, except in the vicinity of each point. In other words, the refractive power in the operational area,
is 6. OD, the refractive power D2 in the near vision region is 8.0D. The distance between points A and B, that is, the length of the progressive zone, is 2
It is 0mm. The maximum slope of the refractive power change on the principal meridian M is O,lOD/mm.

FIG. 8(a) shows the refractive surface in the distance region and the principal meridian M.
The change in refractive power on the line of intersection with the plane perpendicular to is shown. however,
Since the lens of this embodiment has a symmetrical design, only one half of the lens is shown. The refractive power is constant at 6.0D up to a distance of 2 mm from the principal meridian M, then gradually increases to reach 6.5D at a distance of 625 mm from the principal meridian M, and then decreases. In this way, the maximum value is 6.5
By keeping it at D, that is, by keeping the difference with the refractive power on the principal meridian M to within 045D, it is possible to reduce the astigmatism in the distance region to 0.5D or less. There is. Furthermore, by adopting an aspherical surface as described above, compared to a case where a spherical surface is used for the entire distance vision region, the ease of use of the operation region is not impaired (, intermediate region and near vision region fl ( This makes it possible to improve the I11100 characteristics.In other words, the magnification in the lateral distance region increases and approaches the magnification in the intermediate or near region, thereby reducing distortion.

8b shows the change in refractive power on the line of intersection between the refractive surface in the near region and a plane perpendicular to the principal meridian M. FIG. Similar to a in the operation section area, there is a section where the refraction force is constant, but after that it increases and further decreases as the direction of measurement increases. Approximately 7.5mm1ii from the principal meridian M! The refractive power is 7.
0D, so that the width of the region with astigmatism within 1.00 is approximately 15 mm. After determining the refractive power change on the principal meridian M, the operational area, and the near area as described above, the intermediate area is
It was designed using the method shown in .

As a result, the distribution of astigmatism became as shown in FIG. 9. In the figure, for example, the line marked 1.0 is an isoastigmatism line of 1, OD. The minimum width S in the middle region of the region where the astigmatism is within 1.00 is approximately 10 mm, which is significantly wider than the conventional one. The maximum width W in the near vision region is about 15 mm, and the ratio of the maximum width W to the minimum width S is about 1.5 times.

Therefore, the 1.0D isoastigmatism line extends upward from the lower end of the refractive surface approximately parallel to the principal meridian M, and then extends toward the side of the refractive surface.

In this way, unlike in the conventional case, the width of the isoastigmatism line does not suddenly become narrower, so there is no large distortion at the side portion of point B, and the wearing comfort is improved.

That is, from the point of view of reducing the distortion at the side portion of point B, the ratio of the maximum width W to the minimum width S should be approximately 1. O(W:
=S), but considering the width required for the near vision area, it should be approximately 1.5 or less at most.

Note that the length of the progressive zone is long and the width of the area suitable for near vision is narrow, but since the near vision area is only used occasionally, it is recommended to push the glasses slightly upwards. This can be used depending on the situation, as the width of the progressive band is wide. 1. The isoastigmatism line of OD extends upward along the principal meridian M, and then moves laterally. In this example, the fitting point is set on point A, and the rotation of the lens for convergence is 8 degrees. Starting from point A, 1. When a straight line is drawn that is tangent to the isoastigmatism line of OD, it becomes a line that is inclined downward by about 20 degrees from the horizontal line H. Therefore,
Considering the horizontal line when worn as a reference, any refractive surface above a line inclined at approximately 12 degrees will have an astigmatism of 1. It is below OD. Here, if we draw a straight line tangent to the equal mean refractive power line of 6.5D from point A in the average refractive power distribution diagram of this example shown in Fig. 1O, we will find that it is about 21
This is a line that slopes downward. Therefore, initially, horizontal 19 H
Only the upper part was set as the operating area, but the average refractive power was 0.
Since it is the same as the 5DL, the area up to about 21 degrees below the horizontal line H can be used as a distance viewing area in terms of refractive power. Therefore, if we consider astigmatism and average refractive power in total, we can consider that the entire area above a line inclined approximately 12 degrees downward from the horizon when worn is an area suitable for distance vision. 6 In the present invention, which provides a wide distance field of view,
The refractive surface of the lens is divided into distance, intermediate, and near regions, but these names are for convenience; the upper part of the intermediate region is the region suitable for distance vision. The lower part of the intermediate region can also be considered as a region suitable for near vision.

Next, an example in which the addition power is 3.0D will be described.

The arrangement of each region, the refractive power change on the principal meridian M, and the refractive power change in the operation area and near vision area are shown in Figure 11, respectively.
It is shown in FIGS. 12 and 13. The difference when compared with the example in which the addition power is 2.0D is as shown in Fig. 11.
The boundary line between the active area and the intermediate area is closer to the distance area. Furthermore, as shown in FIG. 13b, the change in refractive power within the near vision region is determined, and the refractive power becomes 10 mm at a distance of about 5 mm from the principal meridian M (refractive power 9.0 D).
．． This is done so that it becomes 0D. Both of these mean that the area with small astigmatism becomes narrower in the operation area or the near-river area. This is to avoid the fact that if the area is kept the same, the distortion and shaking of the image will increase rapidly.In this way, as the addition power increases, the area where the astigmatism is small is narrowed. This is a method also used in -AQ, but in the present invention, it has been found that it is possible to make a progressive multifocal lens that is comprehensively easy to use by satisfying the following conditions. When the addition power is expressed as ADD, (1) When worn, the astigmatism is 1.0 above a line inclined downward by [5O-(ADDX20)] degrees from the horizontal line.
Below D. (If the sign is negative, it means that the line is inclined upward.) (2) Astigmatism in the near vision area1. The maximum width of the area within OD is [30÷ADD] mm or less.

This is the condition. Therefore, for (1), the addition is 2
．． If it is 0D, it is preferable that the astigmatism is 1.0D or less above the line 10 degrees below, and if the addition is 3.0D, the astigmatism above the line 10 degrees above is good.

Regarding (2), astigmatism 1. The maximum width of the area within OD is 15 mm or less if the addition is 2.0D, and if the addition is 3.
．． 0D indicates that it is preferably 10 mm or less. It goes without saying that the embodiment with an addition power of 2.0D also satisfies the above conditions. Now, the addition power 3. created in this way. FIG. 14 shows the distribution of astigmatism and FIG. 15 shows the distribution of average refractive power in the OD example. Similar to the addition power 2.0D, the horizontal line when worn is 8 with respect to the horizontal line H.
Assuming that the astigmatism is 1.0D or less, the area where the astigmatism is 1.0D or less is the entire area above a line inclined approximately 9 degrees upward from the horizontal line when worn, and the area where the average refractive power is within 6.0±0.5D. teeth,
Similarly, it is the entire surface above the line that is inclined downward by about 2 degrees. Furthermore, since the maximum width W of the region where the astigmatism is 1.0D or less in the near vision region is about 10 mm, both of them satisfy the above conditions. Astigmatism in the intermediate region 1.0
The minimum width S of the area below D is approximately 7 mm, and the ratio of the maximum width W to the minimum width S is approximately 1.4 times.

In these examples, the refraction force is assumed to be constant above point A (continuous use area) and below point B (near area) on the principal meridian; however, it does not necessarily have to be strictly constant; Even if there is a slight increase or decrease (about 0.5D) in the refractive power at point or point B, the same effect can be obtained.
For example, the refractive power change on the principal meridian may be as shown in FIG. 16 or FIG. 17. Figure 7 and 1
In the case of a lens that exhibits a change in refractive power as shown in Figure 2, point A, which is the lower end of the distance vision region, and point B, which is the upper end of the near vision region, are the points at which the refractive power begins to increase. The point where it ends is also the point where it ends.

The same applies to the lens shown in FIG. In the case of a lens as shown in FIG. 17, the positions where the gradient of increase in refractive power changes are point A and point B. That is, point A is where the gradual increase changes to a relatively rapid increase, and point B is the opposite point. In any of the above cases, the refractive powers at point A and point B are the refractive power 3 in the distance region and the refractive power D2 in the near region, respectively.

As described above in detail according to the embodiments, the present invention provides a wide distance field of view and a wide field of view in the lateral region by incorporating an aspherical surface to a degree that does not impair distance vision in the distance region. An intermediate region and a near vision region with reduced image distortion and vibration can be obtained. In addition, the length of the progressive zone is significantly longer than before, and the gradient of its refractive power change is gentler, ensuring a wide intermediate field of view and continuous field of view, and reducing image distortion and shaking in the lateral areas. . Furthermore, by setting the near field of view narrower than before, a field of view of the same width is secured from the intermediate area to the near area, significantly reducing image distortion and shaking in the lateral areas. . In this way, compared to conventional progressive multifocal lenses, a progressive multifocal lens has been realized that has a wide distance visual field and intermediate visual field, and has very small image distortion and shaking.Therefore, the lens according to the present invention This progressive multifocal lens is ideal for sports such as golf, driving a car, and going out for shopping.

Note that the present invention is not limited to the embodiments described above. For example, although the length of the progressive zone is 20 mm, it is possible to obtain a progressive multifocal lens that can achieve the object of the present invention even with a length of about 18 mm. I know that. At this time, if the refractive power is changed linearly, the addition power is 2.0D.
In this case, the minimum width S of the intermediate region is approximately 9 mm, which is a sufficient width, and the distortion and shaking of the image at the side portions are small. However, the length of the progressive zone is 1
Even if it is 8 mm, if the change in refractive power is like a sine curve, the gradient of the change in refractive power will become large around the center of the progressive zone, which is not preferable. In short, the length of the progressive zone is 18m.
It is sufficient if the lens has a gradient of refractive power greater than or equal to m and less than (addition power divided by length of progressive zone). In addition, in the embodiment, the refractive power on the principal meridian was considered to be almost constant in both the distance and near vision regions, but lenses such as those shown in FIGS. 18 and 19 are also used in this book. within the scope of the invention. In other words, the change in refractive power is almost constant within the distance vision region, but the gradient of increase in refractive power does not change much from the intermediate region to the near vision region, and from the point of view of the position where the gradient of increase in refractive power changes, is a lens in which point B cannot be clearly defined. In the case of such a lens, point B is a point on the principal meridian that has a refractive power approximately 0.5D lower than the refractive power of the lowest end of the fabric lens lO, and the area below this point is the near vision area. determined.

Although the near vision area becomes very narrow, the purpose of the present invention is to place emphasis on distance vision and intermediate vision, but not so much on near vision, so the near vision area may be as small as this.

In addition, although the example is a case of a lens with a bilaterally symmetrical design, a lens with a bilaterally asymmetrical design having a principal meridian as shown in FIG. 5 may also be used. It goes without saying that it should be extremely small, but it doesn't have to be a moon-saipoint curve. Furthermore, in the embodiment, the distance vision, intermediate vision, and near vision regions are arranged on the convex surface side, but these regions can also be arranged on the concave surface side.

[Brief explanation of drawings]

1 to 4 are diagrams showing the structure of the convex refractive surface of a conventional general progressive multifocal lens, changes in refractive power on the principal meridian, distribution of astigmatism, and distortion of a square lattice image, respectively. FIG. 5 is a diagram showing the distribution of astigmatism of another conventional progressive multifocal lens. Figures 6 to 10 show examples of the present invention, with Figure 6 showing the structure of the convex refractive surface, Figure 7 showing changes in refractive power on the principal meridian, and Figure 8 showing the operating section. Figure 9 shows the distribution of astigmatism, and Figure 10 shows the distribution of the average refractive power. Figure shown. 11 to 15 are diagrams showing other embodiments of the present invention. 16 and 17 are diagrams showing another example of the change in refractive power on the principal meridian of the progressive multifocal lens of the present invention. 18 and 19 are diagrams showing still another example of the structure of the convex refractive surface of the progressive multifocal lens of the present invention and the change in refractive power along the principal meridian. l...Operation area 2 ・ 3 ・ 10 ・ 1 l ・ M ・ A ・ B ・ L ・ S ・ W ・ ・ Intermediate area Near vision area Fabric lens (lens before edging) Eyeglass lens (rim Lens after sliding processing Principal meridian Distance center (refractive power DI) Near center (refractive power PA) Astigmatism in the intermediate region of the length of the progressive zone 1. Astigmatism in the near vision region with the minimum width within the OD 1. Maximum width of area within OD Horizontal line of lens When worn, from Horizontal line fitting point

Claims (2)

[Claims] (1) The lens has a principal meridian extending in the vertical direction approximately at the center of the refractive surface, with a distance region above the refractive surface, a near vision region below the refraction surface, the distance region and the distance vision region. Each has an intermediate region between the near vision regions, and the refractive power on the principal meridian is a substantially constant value at least in the distance vision region, and the refractive power of the distance vision region in the intermediate region is equal to the refractive power of the distance vision region. (D
_1 diopter) to the refractive power (D
In a progressive multifocal lens that gradually increases up to _2 diopters, the length of the principal meridian included in the intermediate region is 18 mm or more, and the refractive power on the principal meridian in the intermediate region is The maximum gradient of change is less than or equal to [ADD ÷ 18] diopters/mm, where ADD is the refractive power D in the distance region.
_1 and the refractive power D_2 of the near vision region, that is, ADD=D_2−D_1, and the maximum width W of the region within the astigmatism of 1.0 diopters in the near vision region.
is less than or equal to [30÷ADD] millimeters, where ADD is the difference between the refractive power D_1 of the distance vision region and the refractive power D_2 of the near vision region, that is, ADD=D_2−D
_1, and further ADD≧1.5, and the maximum width W is within 1.5 times the minimum width S in the region where the astigmatism is within 1.0 diopters in the intermediate region, that is, W≦1. A progressive multifocal lens characterized by .5×S. (2) The lens has a principal meridian extending longitudinally approximately at the center of the refractive surface, with a distance region above the refractive surface, a near vision region below the refraction surface, the distance region and the distance vision region. They each have an intermediate region between the near vision regions, and the refractive power on the principal meridian has a substantially constant value at least in the distance vision region, and in the intermediate region, the refractive power of the distance vision region ( D_
1 diopter) to the refractive power (D_
In a progressive multifocal lens that gradually increases up to 2 diopters, the refractive power on the line of intersection between the refractive surface in the distance region and a plane perpendicular to the principal meridian is at a distance of 0 to 10 mm from the principal meridian. It remains constant up to [D
A progressive multifocal lens characterized by reaching _1+0.5] diopters and then decreasing.