JPS6237369B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for manufacturing bifocal contact lenses.

Bifocal contact lenses for both near and far vision generally have a crescent-shaped near point portion 2 in the lower half of a circular far point portion 1, as shown in FIGS. The surface of portion 2, that is, the lens surface for near point, is recessed in the surface of far point portion 1, that is, the lens surface for far point, and intersects with the lens surface for far point at the chord position of the crescent. The conventional method for manufacturing such bifocal contact lenses is to first prepare a disk-shaped lens material 3, as shown in FIG.
is rotated around an axis eccentric from its central axis, and the cutting tool 4 is brought into contact with the lens material surface to cut a far point lens surface 5 on the entire surface of the lens material surface. Then, as shown in FIG. 4, the lens material 3 provided with the far point lens surface 5 is rotated around an axis eccentric from its central axis and cut into half of the far point lens surface. A near-point lens surface 7 is cut into a crescent shape in one half of the far-point lens surface 5 by abutting the tool 6, and the crescent-shaped near-point lens surface 7 is polished. However, the near point lens surface 7 is
Since it is a crescent-shaped lens surface with a recess formed in one half of the far-point lens surface 5, it is extremely difficult to polish it, and therefore, the near-point lens surface 7 cannot be finished with high precision. The chord position of the crescent-shaped near point lens surface 7, that is, the intersection line between the near point lens surface 7 and the far point lens surface 5 cannot be made sharp. Note that if the above-mentioned intersecting lines are not sharp, the image seen through the vicinity of the intersecting lines will be doubled, blurred, or distorted, resulting in an unstable state.

In view of this conventional situation, an object of the present invention is to provide a method for manufacturing a bifocal contact lens in which the near-point lens surface can be easily polished.

The present inventor believes that the reason why it is extremely difficult to polish the near point lens surface in the above conventional manufacturing method is that the near point lens surface has a crescent shape that is difficult to polish, and is located in a half of the far point lens surface. Focusing on this issue, they considered creating a shape that would make the near-point lens surface easier to polish. As a result, the near-point lens surface has a crescent shape placed on one half of the far-point lens surface in the final product, but the near-point lens surface is not limited to that shape in semi-finished products in the process of manufacturing. The processing order of the far point lens surface is reversed from that in the conventional manufacturing method, and first, as illustrated in FIG. 5, the near point lens surface 16 is cut into a circular shape that is easy to polish on the lens material 8 surface. Then, as illustrated in FIG. 6, the surface of the lens material 8 is cut together with a part of the circular near-point lens surface 16 formed on that surface to form the far-point lens surface 2.
9, and at the same time, the idea was to leave a crescent-shaped near-point lens surface 16 in one half of the far-point lens surface 29.

That is, the present invention first cuts a near-point lens surface into a circular shape on a lens material surface, polishes the circular near-point lens surface, and then forms a circular lens material surface on that surface. Cut together with a part of the near point lens surface to form a far point lens surface,
This is a method for manufacturing a bifocal contact lens characterized in that a crescent-shaped near point lens surface remains in a part of the far point lens surface.

In the manufacturing method of the present invention, the near point lens surface has a circular shape during polishing, so it is easier to polish the near point lens surface than in the conventional manufacturing method, which has a crescent shape. Therefore, the near point lens surface can be finished with high precision, and the intersection line of both the near point and far point lens surfaces can be finished sharply.

Next, examples of the present invention will be described.

The manufacturing method in this example involves cutting a concave curved surface, which will become the inner or back surface of a bifocal contact lens, on one plate surface of a disk-shaped lens material mainly made of a hydrophilic monomer such as 2-hydroxyethyl methacrylate. As shown in FIG. 7, the lens material 8 with the concave curved surface 9 formed thereon is fixed by adhering the concave curved surface side to a disc-shaped adhesive jig 10. The lens material 8 is fixed to the main shaft 11 of the lens lathe with a chuck 12 and coaxially attached to the main shaft 11, and while the main shaft 11 is rotated, the cutting tool 13 of the lens lathe is rotated coaxially with the main shaft 11. The other plate surface of the lens material 8 is rotated in an arc having its center on the rotation axis of the lens material 8, and the other surface of the lens material 8 is roughly cut into a convex curved surface 14. Next, as shown in Figure 8,
The cutting tool 15 is brought into contact with the center of the convex curved surface 14 of the lens material again and rotated in a narrow arc shape having its center on the rotation axis of the lens material 8, as shown in FIGS. 8 and 9. A near-point lens surface 16, which becomes the near-point surface of the bifocal contact lens, is cut into a circular shape coaxial with the lens material 8 at the center of the convex curved surface 14 of the lens material. Furthermore, as shown in FIG.
10 and 11.
As shown in the figure, near point lens surface 1 of the lens material
A circular plate-shaped peripheral surface 18 is continuously cut around the periphery of the circular plate 6. Next, the adhesive jig 10 with the lens material 8 attached thereto is removed from the lens lathe, and as shown in FIG. The peripheral surface 1 of the lens material is attached coaxially to the main shaft 19, and the peripheral surface of the lower surface of the disc-shaped polishing jig 21 of the lens polishing machine is rotated coaxially with the main shaft 19.
8 with a polishing liquid interposed therebetween, and swings the polishing jig 21 along the peripheral surface 18 of the lens material to polish the peripheral surface 18 of the lens material. In addition, the polishing jig of the lens polishing disk is replaced with a smaller diameter one, and as shown in FIG. The polishing jig 22 is brought into contact with the near-point lens surface 16 of the lens material with a polishing liquid interposed therebetween, and the polishing jig 22 is oscillated along the near-point lens surface 16 of the lens material to polish the near-point lens surface 16 of the lens material. Next, the adhesive jig 10 to which the lens material 8 is attached is removed from the lens polishing machine, and as shown in FIG. The adhesion jig 10 is coated with a dental wax called "Curl Dental Impression Compound Type" by Shibron Digital Products Division of the United States, and has a lens material 8 with a filler 23 attached thereto. As shown in Figure 15,
The base 25 and the movable plate 26 are fixed to the movable plate surface of the eccentric chuck 24 which are arranged side by side so as to be eccentric, and the base surface of the eccentric chuck 24 is vacuum-adsorbed to the tip of the main shaft 27 of the lens lathe, and the lens material 8 is It is mounted eccentrically on the main shaft 27, and while the main shaft 27 is rotated, the cutting tool 28 of the lens lathe is rotated around the rotation axis of the main shaft 27. It contacts the center and rotates in an arc having its center on the main shaft 27 and the rotation axis, cutting off the filler 23, part of the near-point lens surface 16, and part of the peripheral surface 18, as shown in FIG. As shown in FIG. 16, the far point lens surface 29, which is the surface of the far point portion of the bifocal contact lens, is formed into a circular shape, and a filler 2 is applied to one half of the far point lens surface 29.
3, which leaves a crescent-shaped near-point lens surface 16. Next, the adhesive jig 10 with the lens material 8
The eccentric chuck 24 with the attached lens is removed from the lens lathe, and as shown in FIG. Install the main shaft 30
While rotating, the concave curved lower surface of the polishing jig 31 of the lens polishing machine is applied to the far point lens surface 29 and the filler 23 surface of the lens material, which swings around the rotation axis of the main shaft 30, with a polishing liquid interposed between them. The polishing jig 31 is oscillated along the far point lens surface 29 of the lens material to polish the far point lens surface 29 of the lens material. Next, the filler 23 adhering to the crescent-shaped near-point lens surface 16 is removed. Thereafter, a soft bifocal contact lens as shown in FIGS. 1 and 2 is manufactured through the process of processing the peripheral portion of the lens material 8 in the same manner as in the conventional manufacturing method.

In the manufacturing method of this example, the near point lens surface is
During polishing, it has a circular shape that is easy to polish, and when cutting and polishing the far point lens surface, it is coated with a filler or a protective agent, resulting in a highly accurate finish. In addition, the chord position of the crescent-shaped lens surface for near point, ie, the line of intersection of both lens surfaces for near point and far point, is sharply finished.

Furthermore, the surface that connects the crescent-shaped near-point lens surface to the far-point lens surface is cut and polished as a peripheral surface, so the connecting surface that contacts the blind eyelid is smooth, creating a lens that is comfortable to wear. A focal contact lens is obtained.

The manufacturing method of the example is shown in FIGS. 7 to 17 as described above.
Although it is as shown in the figure, it may be modified as exemplified below.

(1) The periapsis lens surface 16 and the peripheral surface 18, which were cut separately, are continuously cut at one time.

(2) Between the step of polishing the near-point lens surface 16 and the step of coating the near-point lens surface 16 and the peripheral surface 18 with the filler 23, a dye is applied to the near-point lens surface 16 to coat it. Add a dyeing process that uses ultraviolet lamp irradiation. As a result, a trial lens in which only the near point lens surface 16 is colored is obtained, and this trial lens is convenient for examining the relative position between the near point lens surface 16 and the pupil.

(3) Hard bifocal contact lenses are manufactured using lens materials based on hydrophobic monomers such as methyl methacrylate.

[Brief explanation of the drawing]

Figures 1 and 2 are a front view and a vertical cross-sectional view of a bifocal contact lens, and Figures 3 and 4 are the far point lens surface cutting process and the near point lens surface cutting process in the conventional manufacturing method. 5 and 6 are plan views schematically showing an example of the near point lens surface cutting step and the far point lens surface cutting step in the manufacturing method of the present invention, Figures 7 to 17
The figures are diagrams schematically illustrating each step or lens material in the manufacturing method of the embodiment of the present invention, in which FIG. 7 is a plan view of the rough cutting step, and FIG. 8 is a plan view of the near point lens surface cutting step. , FIG. 9 is a front view of the lens material in the same process, and FIG. 10 is a plan view of the peripheral surface cutting process.
Figure 11 is a front view of the lens material in the same process;
Figure 12 is a front view of the peripheral surface polishing process, Figure 13 is a front view of the near point lens surface polishing process, Figure 14 is a front view of the filler coating process, and Figure 15 is the far point lens surface cutting process. FIG. 16 is a front view of the lens material in the same process, and FIG. 17 is a front view of the far point lens surface polishing process. 8: Lens material, 16: Lens surface for near point, 2
9: Lens surface for far point.

Claims (1)

[Claims] 1 Cut a near-point lens surface into a circular shape on the lens material surface, polish the circular near-point lens surface, and use the lens material surface with the circular near-point lens surface formed as the near-point lens. A bifocal contact lens characterized in that a lens surface for far point is formed by cutting together with a part of the surface, and a crescent-shaped lens surface for near point remains in a half part of the lens surface for far point. manufacturing method.