JP2740822B2 - Contact lens and manufacturing method thereof - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a contact lens and a method for manufacturing the same.

[0002]

2. Description of the Related Art Conventionally, as a material for a contact lens, a material mainly composed of polymethyl methacrylate (PMMA) having excellent optical properties, mechanical strength and mechanical workability has been used. In recent years, the importance of oxygen supply through contact lenses has been emphasized in order to properly maintain the metabolism of the cornea, and oxygen-permeable polymers such as polymers containing silicon and fluorine atoms have become increasingly important.
It has been used in place of MMA. Examples of the silicon-containing polymer include a silicone rubber, and a polymer containing acrylate, methacrylate, styryl, or the like having a siloxane bond as one component. on the other hand,
Examples of the fluorine-containing polymer include a polymer containing acrylate or methacrylate having a perfluoro group in a side chain as one component. However, contact lenses made of these polymer materials generally have strong water repellency, and have a strong foreign-body sensation when worn due to poor surface hydrophilicity.
In addition, a drawback has been pointed out that the secretions are liable to adhere to the film, so that it is easily clouded. Various surface treatments have been studied to improve the hydrophilicity, that is, the wettability of such a polymer material. For example, Japanese Patent Publication No. 58-39450,
JP-A-57-35443, JP-A-58-174412
Each of the publications discloses a method of bonding a polymerizable component having a hydrophilic functional group to a contact lens by post-treatment. Also, Japanese Patent Publication No. 55-49288,
Each publication of -216222 discloses a method for improving the hydrophilicity of the contact lens surface by plasma surface treatment or plasma polymerization. However, in the method of bonding a hydrophilic functional group to a contact lens by a post-treatment method, there are drawbacks that the material that can be made hydrophilic is limited, and that the oxygen permeability of the material is reduced.
In addition, the hydrophilic treatment is also difficult, and there is a high risk of damaging the lens surface during this treatment operation, which is not preferable. In addition, the method of introducing a hydrophilic group into the surface of a contact lens by plasma treatment or plasma polymerization has the disadvantage that the durability of the hydrophilic group is poor and the hydrophilicity is significantly reduced after a long time. To solve these problems,
The authors have proposed a crystalline, water-insoluble silk fibroin membrane.
Tried to apply as a contact lens material
(JP-A-63-246169). However, this silk
Contact lenses made of broin film are biocompatible
Excellent with good oxygen permeability and can be obtained with conventional synthetic polymer materials
Although it has characteristics that cannot be obtained,
According to their studies, optical characteristics such as optical distortion and lens
It turned out that there was some problem in workability, for example, polishing.
Was.

[0003]

[0008] The present invention, oxygen permeability, optical properties, mechanical strength, together with excellent Oite the polishing properties, excellent wearing feel, further stain-resistant, and excellent biocompatibility It is an object to provide a contact lens and a method for manufacturing the same.

[0004]

Means for Solving the Problems The inventors of the present invention have conducted intensive studies to solve the above-mentioned problems, and as a result, have obtained a transparent block obtained from silk fibroin, which is a natural polymer derived from insects. It has been found that the above problem can be solved by using the material for a tonto lens, and the present invention has been completed. That is, according to the present invention, the transparent broth of silk fibroin
Provided is a contact lens comprising a lock body . Also,
According to the present invention, a silk fibroin block containing 5 to 30% by weight of silk fibroin and containing substantially no electrolyte impurities is put into a container, and the water content of the aqueous solution is removed by evaporation to prepare a silk fibroin block. A method for manufacturing a contact lens, comprising cutting and polishing a block body into a contact lens shape is provided.

[0005] In the present invention, silk fibroin is used as a contact lens material. As the silk fibroin, various types of conventionally known silk fibroins are used. For example, silk fibroin derived from non-silkworm, natural silkworm, and Eri silkworm can be used in addition to silk fibroin derived from silkworm. Also,
The silk fibroin may be a regenerated silk fibroin prepared by once dissolving a silk fibroin obtained by purifying a cocoon thread or a raw silk, or a liquid fibroin in a silk gland taken out from a silkworm body.

To manufacture the contact lens of the present invention, first, an aqueous solution of silk fibroin containing 5 to 30% by weight of silk fibroin and containing substantially no electrolyte impurities is prepared. Preparation of such an aqueous solution of silk fibroin can be performed by a conventionally known method, one example of which is shown below. The cocoon thread and raw silk are immersed in a mixed solution of 0.2% by weight malyal soap and 0.05% by weight of sodium carbonate.
The silk sericin on the fiber surface is removed by scouring at 1 ° C. for 1 hour. The silk fibroin fiber produced in this way is concentrated calcium chloride aqueous solution, calcium nitrate aqueous solution,
Since it is dissolved in a neutral salt aqueous solution such as a lithium bromide aqueous solution or a lithium thiocyanate aqueous solution, a silk fibroin aqueous solution can be prepared using these. That is, silk fibroin fibers are dissolved in these neutral salt aqueous solutions to give silk fibroin aqueous solutions, which are then dialyzed with a cellulose dialysis membrane, and lithium ions, calcium ions, thiocyanate ions, and bromide ions contained in the aqueous solutions. ion,
Alternatively, chloride ions and the like are removed from the aqueous solution. As a result, a silk fibroin aqueous solution substantially free of electrolyte impurities can be obtained. A coloring agent or an ultraviolet absorber can be added to this aqueous solution as needed. The aqueous solution of silk fibroin thus prepared is spread on a polyethylene membrane and dried by blowing air to concentrate the aqueous solution of silk fibroin. This is left to stand in a refrigerator for one day and further concentrated to obtain an aqueous solution of silk fibroin having a silk fibroin concentration of 5 to 30% by weight, preferably 7 to 20% by weight. 1 In the present invention, the silk fibroin aqueous solution of 5 to 30% by weight obtained as described above is then placed in a polyethylene container, and further dried,
Obtain silk fibroin block. Drying of the aqueous solution of silk fibroin filled in a polyethylene container takes 5 to 90 days.
C., preferably 20 to 50 ° C., and by drying, a transparent silk fibroin block having a shape corresponding to the shape of the container can be obtained. The container for filling the aqueous solution of silk fibroin is not limited to the one made of polyethylene, but may be another resin or glass. In the present invention, a contact lens is obtained by cutting and polishing the thus obtained transparent silk fibroin block into a contact lens shape by a conventional method. This contact lens is
At the time of use, it absorbs 8 to 15% by weight of water, and is used in this water absorbing state.

[0007]

Next, the present invention will be described in detail with reference to examples, but the present invention is not limited to these examples. Example 1 6 g of scoured silk fibroin fiber was divided into 3 portions of 2 g each for 8.5 g of lithium bromide (LiBr.H ₂ O) having a molar concentration of 8.5 mol.
The solution is added to 20 ml of the aqueous solution and dissolved at 55 ° C. with stirring. After about 30 minutes, the completely dissolved solution is put into a cellulose dialysis membrane and dialyzed against tap water for 3 days to remove lithium ions and bromide ions. Next, substitute pure water for 5 ° C.
Dialysis is performed for another 2 days under the conditions described above. The silk fibroin aqueous solution containing no electrolyte impurities thus obtained is spread on a polyethylene membrane, dried by blowing air, and concentrated. further,
Leave to stand in a refrigerator at 5 ° C. for one day in an open state to dry and concentrate.
20 ml of the aqueous solution of about 9.5% by weight of silk fibroin thus obtained is placed in a polyethylene container having a diameter of 30 mm and a height of 50 mm, and dried in a constant temperature room at 25 ° C. for 2 days in an open state. By this operation, a transparent silk fibroin block having a diameter of 25 mm and a height of 8 mm is obtained. From this solid material, a contact lens was produced by a usual cutting and polishing method. This was immersed in a preservation solution for 2 days to obtain a contact lens having absorbed about 12% by weight of water.

Example 2 Lithium thiocyanate (LiSCN · 2H ₂ O) 3 was prepared by dividing 6 g of refined silk fibroin fiber into 3 times each 2 g.
4g) Add about 3 ml at 45 ° C to an aqueous solution consisting of 10 ml of water.
Dissolution treatment was performed for 0 minutes. Hereinafter, the same operation as in Example 1 was performed,
A transparent silk fibroin block was obtained, and a contact lens was prepared by a cutting and polishing method. This was immersed in a preservation solution for 2 days to obtain a contact lens having absorbed about 13% by weight of water.

Example 3 6 g of refined silk fibroin fiber was divided into 3 portions of 2 g each, and calcium chloride (CaCl ₂ .2H ₂₎ immediately after boiling was divided.
O): Ethanol: water = 1: 2: 8 (mo1%) is added to 50 g of an aqueous solution, and dissolution treatment is performed while gradually cooling. Thereafter, the same operation as in Example 1 was performed to obtain a transparent silk fibroin block, and a contact lens was produced by a cutting and polishing method. This was immersed in a preservation solution for 2 days.
A contact lens absorbing 5% by weight of water was obtained.

Example 4 Silkworm cocoon fiber was immersed in an aqueous solution of 0.1% by weight of sodium peroxide at 50 times the fiber weight and treated at 98 ° C. for 1 hour to remove silk sericin. The silk fibroin fiber obtained by removing the silk sericin was added to an 8 M aqueous solution of lithium thiocyanate (LiSCN · H ₂ O),
Dissolve in 35 minutes at 35 ° C. Thereafter, the same operation as in Example 1 was performed to obtain a transparent silk fibroin block, and a contact lens was produced by a cutting and polishing method. This was immersed in a preservation solution for 2 days to obtain a contact lens having absorbed about 11% by weight of water.

For these contact lens samples,
Its appearance, properties, hardness (Vickers hardness), oxygen permeability coefficient [10 ⁻¹¹ ml (O ₂ ) cm / cm ² · sec · m
m / lg], stain resistance and biocompatibility. Table 1 shows the results. Table 1 shows the evaluation results of contact lenses made of polymethyl methacrylate as Comparative Example 1 for comparison . In addition, the biocompatibility was evaluated on the basis of the following five stages of the wearing feeling when the contact lens sample was worn for one week. (Evaluation criteria for biocompatibility): a: very good (no foreign-body sensation) b: good (no foreign-body sensation) c: normal (somewhat foreign-body sensation) d: foreign-body sensation e: Strong feeling of foreign substances. Stain resistance was evaluated as follows. Egg white lysozyme 0.1 g) Mucin 0.1 g and albumin 0.1
g was dissolved in 100 ml of pure water, and the pH was adjusted to 7.2 with an aqueous solution of disodium hydrogen phosphate (anhydrous) and an aqueous solution of sodium dihydrogen phosphate (anhydrous). This is referred to as a contaminated liquid (A). One lens is added to 1 ml of this contaminated liquid (A) for 60-70.
After immersion at 15 ° C. for 15 minutes, it is dried at room temperature. After repeating this operation five times, the lens washed with purified water and dried while gently rubbing with a finger is visually observed.

[0012]

[Table 1]

The contact lens obtained in Example 1 above
And the method described in JP-A-63-246169.
The following shows the optical distortion and polishing properties of the contact lens (Comparative Example 2)
Was evaluated based on the following criteria. Table 2 shows the results. [Optical distortion] Determine whether distortion or interference fringes are observed in the appearance of polarized light.
It is evaluated using a strain tester for contact lenses. ++: No distortion or interference fringe is observed in the appearance of polarized light
No. +: Some distortion and interference fringes were observed in the appearance of polarized light
You. [Polishability] The surface state of the lens after polishing is visually observed. ：: There is almost no roughness on the lens surface. Δ: The lens surface is slightly rough.

[Table 2]

[0014]

The contact lens of the present invention is safe because it is made of pure silk fibroin, which is a biopolymer derived from insects with low bioreactivity, and is safe from the evaluation results shown in Table 1. It has excellent oxygen permeability and water wettability, is excellent in stain resistance, and has an excellent biocompatibility that cannot be obtained with conventional synthetic polymer materials. Also, it can be seen from the evaluation results shown in Table 2.
As described above, a contact formed from a conventional silk fibroin membrane
Less optical distortion than torens and excellent polishing workability
It is of great practical value. And the present invention
According to the above, without special production process, simply concentrate
Put the silk fibroin solution into a polyethylene container
By drying separately, it is rich in processability and has no optical distortion.
A clear block can be obtained and this is cut and polished
As a result, a contact lens that is highly practical can be obtained.

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Yoshinori Kikuta 5- 25-11 Segasaki, Urawa City, Saitama Prefecture (72) Inventor Miwa Murayama 1371 Otaniguchi, Urawa City, Saitama Prefecture Examiner Satoko Hirai (56) References JP 63-246169 (JP, A) JP-A-2-233128 (JP, A)

Claims (2)

(57) [Claims] 1. A contact lens comprising a transparent block of silk fibroin. 2. A silk fibroin block containing 5 to 30% by weight of silk fibroin and containing substantially no electrolyte impurities is placed in a container, and the water content of the aqueous solution is removed by evaporation to produce a silk fibroin block. A method for producing a contact lens, comprising cutting and polishing a body into a contact lens shape.