JP2752761B2 - Intraocular lens - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention aims to restore visual acuity by placing the lens into the anterior chamber or posterior chamber of an eye that has become aphakic after a lens extraction operation due to cataract or the like. The present invention relates to an intraocular lens (artificial lens) capable of performing the following.

[Conventional technology]

As a method of restoring visual acuity (refraction correction) of a patient who has aphakic eye after cataract extraction surgery due to cataract or the like, use of eyeglasses, wearing of contact lenses, and implantation of intraocular lenses are performed.

However, although eyesight correction can provide visual acuity after surgery, patients suffer from narrowing of the visual field (enlargement of the retinal image) and jack-in-the-box phenomena. , For a period of time. In particular, in the case of a monocular aphakic eye, a binocular vision function cannot be obtained due to unequal image viewing. It is effective to wear a contact lens for such unequal image vision, and at present, a high moisture content soft contact lens and the like have been developed and can be worn continuously, and this problem is being solved. At present, there are few people who actually wear it even after prescribing after surgery because of the difficulty of handling.

[Problems to be solved by the invention]

Thus, correction with eyeglasses and contact lenses is not a preferred method. In contrast, artificial lens transplantation is a method that has already been performed for 30 years,
An artificial lens, a so-called intraocular lens, has a small retinal image enlargement, does not have a narrowed visual field or an annular scotoma, and can provide a binocular vision function. ), There are many advantages because there is no time required for getting used to, and once transplanted, there is no handling. In recent years, with the development of microscopes and ultrasonic scalpels, transplantation surgery techniques have been improved, and the shape and material of intraocular lenses have been further improved.The above-mentioned intraocular lenses will be used as a method of correcting vision in aphakic eyes in the future. The most important one.

As described above, the intraocular lens is very excellent in correcting vision, but since the intraocular lens is an intraocular foreign body, eye complications are a problem, causing corneal endothelial damage and eventually decompensation and blindness. In some cases, it leads to Therefore, it is required that the material of the intraocular lens has no biotoxicity, is excellent in biocompatibility, and is not subject to modification, deterioration and the like from the living body side.

By the way, natural light also includes wavelengths in the ultraviolet, visible, and infrared regions, and transmission of a large amount of ultraviolet light into the eye may cause damage to the retina. Since the lens of the eye also plays a role of protecting the retina by preferentially absorbing the ultraviolet rays, transmission of the ultraviolet rays is a serious problem in the aphakic eye as described above. For this reason, it is desired that the material of the intraocular lens absorb ultraviolet rays in the 200 to 380 nm region and be transparent to visible light in the 380 to 780 nm region. Further, if the above-mentioned intraocular lens itself is heavy, a burden is imposed on the eye. Therefore, it is desired that the material of the intraocular lens is essentially low in specific gravity and high in refractive index so that the lens thickness can be reduced.

Currently, the most used intraocular lens is polymethyl methacrylate (PMMA). This PMMA has excellent optical properties, is resistant to acids, alkalis, and organic solvents, and is resistant to aging.

However, the above PMMA has a glass transition temperature (Tg) of 10
Autoclave sterilization using steam cannot be performed due to low thermal stability of 5 ° C. That is, since autoclave sterilization is usually performed under the conditions of 121 ° C., 1.2 atm, and about 1 hour, PMMA is softened and deformed under these conditions, making it unusable. Therefore, an intraocular lens made of PMMA is sterilized by a sterilization method using ethylene oxide gas, etc., but gas remains in the lens, and when this is put into the eye, the mucous membrane inflames. May be caused. For this reason, in the gas sterilization method, degassing is an essential step, and it takes about two weeks, which increases the cost and is more expensive than the steam autoclave method. .
Also, because PMMA transmits significant UV light, UV light can cause retinal damage, as discussed above. For this reason, as described in Japanese Patent Application Laid-Open No. 60-232149, the above problem has been solved by adding an ultraviolet absorber. However, the addition of the ultraviolet absorber in this manner also deteriorates the transmittance of visible light, or the ultraviolet absorber gradually leaches out of the lens, which may adversely affect the living body. Not really. Further, since the above-mentioned PMMA has a refractive index of about 1.49 smaller than that of glass, the lens becomes thick, and the lens may adhere to the pupil and cause complications.

As described above, although PMMA has many advantages, it also has many disadvantages. Therefore, various materials having a high refractive index that can be sterilized in an autoclave, can absorb ultraviolet rays, and have been studied.
For example, glass has a high refractive index and can absorb ultraviolet light, but it is difficult to process and has a large specific gravity (2.5), so the lens itself becomes heavy and the burden on the eyes increases. There is a problem with use. Natural or synthetic crystals such as sapphire, ruby, corundum, silicon, and diamond also have the ability to absorb ultraviolet light, but, like glass, are difficult to process and have a high specific gravity. Appropriate. For this reason, interest in synthetic resins replacing PMMA has recently been growing, and polysulfone, polyarylate, polyetherimide, and the like are being studied. The polysulfone has a high refractive index, also has an ultraviolet absorbing property, has a softening point of 175 ° C., and can be sterilized in an autoclave. Can not. Polyarylate also has a high refractive index and ultraviolet absorption, and can be sterilized in an autoclave. However, similarly to the above polysulfone, there is a problem in workability, and there is a problem in practical use. In addition, polyetherimide has good processability in addition to high refractive index, ultraviolet absorption, and autoclave sterilization, but is colored yellow or tan, and has a too low visible light transmission amount. It cannot be used as an inner lens.

As described above, although PMMA has the above-mentioned drawbacks, no alternative material has been found. The fact is that it is used as an intraocular lens material by the addition of an ultraviolet absorber which may have an adverse effect on the environment.

Therefore, it can be easily processed into a thin lens shape by machining or molding, and has a specific gravity of 1.7
Below, preferably 1.5 or less, the refractive index is 1.5 or more, preferably 1.6 or more, further chemically stable, and has biocompatibility, absorbs dangerous ultraviolet rays to the retina, In addition, there is a strong demand for the development of an intraocular lens material having heat resistance that enables autoclave steam sterilization.

The present invention has been made in view of such circumstances,
Its purpose is to provide an intraocular lens that is excellent in biocompatibility and ultraviolet absorption, has a small specific gravity as described above, has a high refractive index, is chemically stable, and has heat resistance that enables autoclave steam sterilization. And

[Means for solving the problem]

In order to achieve the above object, an intraocular lens according to the present invention includes a lens portion and a fixing portion for fixing the lens portion in an eye, wherein the lens portion is a repeating unit represented by the following general formula (I). The configuration is such that it is made of colorless and transparent polyimide whose main component is a unit.

[Effect] That is, the present inventors have studied a series of resins in order to obtain an intraocular lens superior to the above-mentioned PMMA, and as a result, the aromatic polyimide completely absorbs ultraviolet light, and It has a high refractive index (1.6 or more) and has sufficient heat resistance to perform autoclave steam sterilization.
It has been found that it has better characteristics than MA.
However, since the aromatic polyimide is colored yellow or brown, not only ultraviolet rays but also visible rays are absorbed to a considerable extent. Thus, the present inventors have conducted research on the development of an aromatic polyimide that does not absorb visible light, and as a result, when an aromatic polyimide containing a repeating unit represented by the above general formula (I) as a main component is used, an ultraviolet ray is not obtained. And absorbs most of the visible light to obtain a substantially transparent intraocular lens, which, like conventional aromatic polyimides, has the properties required for an intraocular lens. And found that it was also excellent in biocompatibility, and reached the present invention.

That is, the intraocular lens of the present invention has a lens portion that is biocompatible, chemically inert, does not undergo modification or deterioration from the living body side, has a refractive index of 1.6 or more, and has a refractive index of 200 to 38.
A colorless and transparent polyimide that completely absorbs ultraviolet light in the 0 nm region, is substantially transparent to visible light in the 380 to 780 nm region, and has heat resistance enough to withstand autoclave sterilization [in the general formula (I)] The main component is a repeating unit represented].

The intraocular lens according to the present invention includes a lens unit and a fixing unit for fixing the lens unit in the eye. This fixing portion is integrated with the lens portion or separate from the lens portion. The lens portion or both of the lens portion and the fixed portion integrated with each other are made of a colorless and transparent polyimide having a repeating unit represented by the general formula (I) as a main component. Here, in the present invention,
The term “principal component” is intended to include the case where the whole is composed only of the principal component. Such a colorless and transparent polyimide is, for example, represented by the following general formula (II) 2,2-bis (3,4-dicarboxyphenyl) hexafluoropropane dianhydride represented by the following general formula (II
It is obtained by reaction with an aromatic diamino compound represented by I).

Specific examples of the aromatic diamino compound include those represented by the following structural formula.

4,4'-diaminodiphenyl sulfone 3,3'-Diaminodiphenylsulfone The above aromatic diamino compounds may be used alone or in combination.

As described above, the above-mentioned 2,2-bis (3,4-dicarboxyphenyl) hexafluoropropane dianhydride and the above-mentioned aromatic diamino compound are reacted in combination to be represented by the general formula (I) for the first time. And a colorless and transparent polyimide containing repeating units as main components.

In this case, the higher the content of the repeating unit represented by the above general formula (I), which is the main component of the colorless and transparent polyimide, the higher the colorless transparency of the obtained polyimide.

However, if the content of the repeating unit represented by the general formula (I) is at least 80 mol%, at least the ultraviolet absorption and visible light transmission required in the present invention will be ensured. Other aromatic tetracarboxylic dianhydrides other than 2-bis (3,4-dicarboxyphenyl) hexafluoropropane dianhydride and other diamino compounds other than the above aromatic diamino compounds can be used. That is, the above general formula (I)
Is preferably 80 mol% or more, and most preferably 95 mol% or more.

The other aromatic tetracarboxylic dianhydrides include pyromellitic dianhydride, 3,3 ', 4,4'-biphenyltetracarboxylic dianhydride, 3,3', 4,4'-benzoic anhydride Phenonetetracarboxylic dianhydride, 4,4'-oxydiphthalic dianhydride, bis (3,4-dicarboxyphenyl) sulfone dianhydride, 2,3,6,7-naphthalenetetracarboxylic dianhydride Products, 1,2,5,6-naphthalenetetracarboxylic dianhydride, 1,4,5,8-naphthalenetetracarboxylic dianhydride and the like, and these can be used alone or in combination.

Other diamino compounds include 4,4'-diaminodiphenyl ether, 4,4'-diaminodiphenylmethane, 3,3'-diaminobenzophenone, 4,4'-diaminodiphenylpropane, p -Phenylenediamine,
4,4'-diaminodiphenylthioether, 2,2-bis (4-aminophenyl) propane, 2,2-bis [4-
(4-Aminophenoxy) phenylhexafluoropropane and the like can be mentioned, and they can be used alone or in combination.

The colorless and transparent polyimide used as the material of the intraocular lens of the present invention is, for example, a polyamide obtained by polymerizing the aromatic tetracarboxylic dianhydride and the aromatic diamino compound in an organic polar solvent at a temperature of 80 ° C. or less. An acid is synthesized, a shaped body having a desired shape is formed using the polyamic acid solution, and the shaped body is heated in air or an inert gas at a temperature of 50 to 350 ° C. and a pressure of normal pressure or reduced pressure. It is obtained by evaporating and removing the organic polar solvent below and simultaneously dehydrating and cyclizing the polyamic acid to form a polyimide. The polyamic acid can also be obtained by a chemical imidization method, such as using a benzene solution of pyridine and acetic anhydride to remove the solvent and imidize to obtain a polyimide.

In the above method, it is also possible to isolate the polyamic acid by reprecipitation, and then to subject it to dehydration and ring closure with heating or a chemical imidizing agent to obtain a polyimide. further,
The solution obtained after the synthesis of the polyamic acid is directly heated to 100 ° C. or higher for imidization, and polyimide can be obtained as a precipitate from the solution. In this case, it is necessary to wash by filtration, but this also gives substantially the same colorless and transparent polyimide.

Amide organic polar solvents such as N, N-dimethylformamide and N, N-dimethylacetamide are suitable as the organic polar solvent. In particular, those having a boiling point of 170 ° C. or lower such as N, N-dimethylacetamide are preferable. These organic polar solvents may be used alone or as a mixture of two or more. However, it is preferable to avoid using N-methyl-2-pyrrolidone as the organic polar solvent. N-methyl-2-pyrrolidone is
The immobilized body of the polyamic acid solution is heated, and partially decomposed by heating at the time of dehydration and ring closure to form a polyimide, and the decomposed product remains so as to exhibit a dark brown color, which causes the resulting polyimide to be colored yellow-brown. This is because there is a tendency.
As the organic polar solvent, each of the solvents exemplified above, such as N, N-dimethylacetamide, has a low boiling point, so that it is volatilized before being decomposed by the above-mentioned heating, and N-methyl-2
-No coloring to polyimide such as pyrrolidone.

However, after N-methyl-2-pyrrolidone is used as a polymerization solvent and the polyamic acid is synthesized, the polyamic acid solution is poured into a poor solvent for the polyamic acid, for example, water, to reprecipitate the polyamic acid, and the non-polymerization solvent In the case of imidizing in the presence or in the case of imidizing after re-dissolving in another preferable solvent, the above-mentioned adverse effects of N-methyl-2-pyrrolidone can be eliminated.

In addition, when using the suitable organic polar solvent exemplified above, ethanol, toluene, benzene,
Use poor or good solvents such as xylene, dioxane, tetrahydrofuran, and nitrobenzene that do not impair transparency.
One type or two or more types may be appropriately mixed and used as long as the solubility is not impaired. However, when these solvents are used in a large amount, the solubility of the resulting polyamic acid is adversely affected. Thus, it is appropriate to limit the amount used to less than 50% by weight of the total solvent, most preferably to no more than 30% by weight.

As described above, when producing a colorless and transparent polyimide, the intrinsic viscosity (logarithmic viscosity) of the polyamic acid solution is 0.3 to
It is preferably in the range of 5.0. More preferred is 0.4-
2.0. The intrinsic viscosity is a value measured at a concentration of 0.5 g / 100 ml in N, N-dimethylacetamide. If the intrinsic viscosity is too low, the mechanical strength of the obtained intraocular lens becomes low, which is not preferable. On the other hand, if the intrinsic viscosity is too high, the operation of shaping the polyamic acid solution into an appropriate shape or the operation of isolating the polyamic acid becomes difficult, which is not preferable. Further, the concentration of the polyamic acid solution is preferably set to 5 to 30% by weight, preferably 15 to 25% by weight from the viewpoint of workability and the like.

The intrinsic viscosity is calculated by the following equation, and the viscosity in the equation is measured by a capillary viscometer.

Examples of a method for producing an intraocular lens using the colorless and transparent polyimide obtained as described above include the following method.

In the first method, first, the polyamic acid solution is cast on a mirror-finished glass plate, stainless plate, or the like so as to have a constant thickness, and gradually heated at a temperature of 100 to 350 ° C. to close the dehydration ring. Then, the polyamide acid is imidized to obtain a polyimide film. In this case, the removal of the organic polar solvent in the film formation from the polyamic acid solution and the heating for the imidization of the polyamic acid may be performed continuously, and these steps may be performed under reduced pressure or in an inert gas atmosphere. You may use it. Another method of forming a polyimide film is to cast the above polyamic acid solution on a glass plate or the like, and heat and dry at 100 to 150 ° C. for 30 to 120 minutes to form a film. This is a method in which the film is immersed in a benzene solution of acetic acid and the like, and the solvent is removed and an imidization reaction is carried out to convert the film into a polyimide film. This method can also be used to obtain a polyimide film. Next, the required number of sheets of the polyimide film thus obtained was stacked so as to form a plate-like molded body having a constant thickness, and the temperature was lowered.
Hot-pressing is performed at 200 to 400 ° C and 0.5 to 10 t / cm ² for 0.1 to 10 hours. Thereby, a transparent molded article of polyimide is obtained. This is polished into an intraocular lens using a polishing apparatus to obtain an intraocular lens.

In the second method, first, a polyamic acid solution is poured into a poor solvent such as water or methanol to reprecipitate and recover the polyamic acid, and then heated at a temperature of 100 to 350 ° C. to dehydrate and ring-close to imidize. Then, pulverization is performed to obtain anhydrous transparent polyimide powder. Next, using this powdery polyimide, as described above, at a temperature of 200 to 400 ° C. and a pressure of 0.5 to 10 t / c.
Hot pressing at m ² for 0.1-10 hours. Thereby, a transparent polyimide molded body is obtained. Then, this is a method of polishing into an intraocular lens in the same manner as described above.

In the second method, as another method for obtaining a powdery and colorless transparent polyimide, the polyamic acid is converted into the polyimide by heating the polyamic acid solution to 100 to 200 ° C. while stirring, and further as a precipitate. There is a method of precipitating out of the system, and in this case, it is possible to provide for hot pressing only by cleaning and drying.

In this way, when an intraocular lens is produced using a colorless and transparent polyimide film or polyimide powder, the obtained intraocular lens has an intrinsic viscosity (0.5 g / dl in 97% sulfuric acid) in terms of mechanical strength. , Measured at 30 ℃)
Is preferably set in the range of 0.3 to 4.0. Most preferred is 0.4 to 2.0.

The third method is similar to the first and second methods described above.
This is not a method using hot pressing, but a method for obtaining a polyimide molded body directly from polyamic acid. In the conventional drying method, foaming cannot be suppressed by such a method,
It is difficult to obtain a homogeneous polyimide molded body of 150 μm or more. However, by leaving the polyamic acid solution under reduced pressure for a long time and heating from inside using far infrared rays or microwaves, 500 μm
The above polyimide molded body can be obtained. In other words, by using such far-infrared rays and microwaves, a homogeneous polyimide molded article can be obtained directly from polyamic acid.

Manufacture of an intraocular lens from the polyimide molded body obtained by the above three methods can be performed by, for example, machining. In other words, the lens is made by polishing the curved surface in accordance with the power, then NC processing (numerical control processing) is performed on the hole for attaching the fixing part, and the fixing part is welded to this hole by spot heating. Can be. An example of an intraocular lens obtained as described above (an intraocular lens to be implanted in the posterior chamber of the human eye) is shown in FIG. 1 and FIG. In the figure, 1 is a lens portion, 2 is a position adjusting hole formed along the circumference at the peripheral edge of the lens portion 1, and 3 is the lens portion 1
Is a fixing part for fixing the in the eye.

The shape of the fixing portion 3 is various and can be changed as needed. As the material of the fixing portion 3, polypropylene, polyvinylidene fluoride or the like is often used. However, in the intraocular lens according to the present invention, these materials may be used, or other materials may be used. Further, a colorless and transparent polyimide of the same material as the lens portion may be used.

As described above, instead of providing the lens portion and the fixing portion separately and connecting them, the lens portion and the fixing portion may be formed by integrally molding the lens portion and the fixing portion. An intraocular lens 4 in which such a lens portion and a fixed portion are integrally formed.
Are shown in FIGS. 3 and 4. In this case, since there is no joint between the two, the occurrence of a situation in which the fixed portion is detached from the lens portion is avoided.

The intraocular lens obtained in this manner is quite different from the one produced using a conventional aromatic polyimide, and has extremely high transparency.

In the case of a film-shaped molded product having a thickness of 50 μm, the colorless and transparent polyimide used in the present invention has a visible light (500 nm) transmittance of 80% or more and a yellowness (yellowness index) of 30%. These are: When the lens portion of the intraocular lens of the present invention has a thickness of 1 mm, the total visible light transmittance (total light transmittance) is 60%.
% Or more.

The reason that the lens portion of the intraocular lens of the present invention completely absorbs ultraviolet light, transmits most of visible light, and is substantially transparent is that the transmittance is measured by measuring the ultraviolet-visible light spectrum. The point at which is zero (the so-called cut-off point) is just the boundary point between the ultraviolet region and the visible light region (380n
m), which is thought to be due to this cut-off occurring almost vertically. Among the aromatic polyimides other than the colorless and transparent polyimide used in the present invention, there are cutoffs having a cutoff of around 380 nm.However, the transmittance gradually decreases from the higher wavelength side, and therefore, the total light transmittance is remarkably increased. It is worse and therefore cannot be applied to the use of intraocular lenses.

〔The invention's effect〕

As described above, the intraocular lens of the present invention has a lens portion obtained by combining 2,2-bis (3,4-dicarboxyphenyl) hexafluoropropane dianhydride with the specific aromatic diamino compound. Because it is made using the obtained colorless and transparent polyimide, it can completely absorb ultraviolet rays in the 200 to 380 nm region, and transmits most of the visible light in the 380 to 780 nm region, and has substantial transparency. ing. Therefore, when implanted in the eye, harmful ultraviolet rays can be absorbed and cut to protect the retina and provide sufficient visual acuity. In addition, the colorless and transparent polyimide usually has a specific gravity as low as 1.3 to 1.4 and a refractive index of 1.6 to 1.7, which is larger than that of conventional PMMA. Up to 50% can be made thin (thus light). Therefore, when implanted in the eye, the burden on the eye is light, and the possibility of complications due to contact with the cornea is low, and the safety is extremely high. Moreover, since the lens portion of the intraocular lens of the present invention is made of colorless and transparent polyimide which is not different from conventional aromatic polyimide in terms of heat resistance, it can be easily sterilized using an autoclave steam sterilization method. And cost reduction can be achieved.

The intraocular lens of the present invention can be used as an anterior chamber supporting lens and a posterior chamber supporting lens, and in some cases, as an iris supporting lens, and includes all of them.

 Next, examples will be described together with comparative examples.

[Examples 1 to 5] Using N, N-dimethylacetamide as a solvent,
1 mol of each diamino compound shown in the table below was reacted with 1 mol of 2,2-bis (3,4-dicarboxyphenyl) hexafluoropropane dianhydride to obtain a polyamic acid solution. The concentration of the polyamic acid polymer in the polyamic acid solution was set to be 20% by weight. This solution was cast on a glass plate to form a film, which was heated at 120 ° C. for 6 hours in a hot air drier.
0 minutes, 180 ° C for 60 minutes, 250 ° C for 3 hours, and at 300 ° C
A polyimide film having a thickness of 50 μm was prepared by heating for 30 minutes for imidization. When the infrared absorption spectrum of the polyimide film thus obtained was measured, no absorption of amic acid was observed, and 1780 cm
^{At -1} , characteristic absorption of the imide group was observed.

The above polyimide film was punched with a punch having a diameter of 38 mm, and 20 sheets were piled on each other at a temperature of 300 ° C., a pressure of 1 t / cm ² , and a molding time of 30 hours.
A 1 mm-thick polyimide disk-shaped molded body was produced by hot-press molding under the conditions of minutes. In these molded products, the films were completely fused and integrated, and were homogeneous polyimide molded products.

The ultraviolet light of the polyimide molded body thus obtained is
The visible light spectrum was measured to determine the wavelength at the cut-off point. Further, the total light transmittance, specific gravity and refractive index were determined, and the results are shown in the table below. Further, a pressurized cooker test at 121 ° C. and 1.2 atm for 24 hours was conducted to examine changes in appearance, and the results are shown in the same table.

[Comparative Example 1] N-methyl-2 was used instead of N, N-dimethylacetamide.
-Pyrrolidone and 4,4'-diaminodiphenyl ether as the diamino compound. Otherwise, the procedure of Example 1 was repeated to prepare a polyimide film. In the infrared absorption spectrum of this film, no absorption of amic acid was observed, and absorption of an imide group was observed at 1780 cm ^-1 .

Using the polyimide film thus obtained,
By the same procedure as in Example 1, a 1 mm-thick polyimide molded body was produced. This molded product had a large coloring and it was impossible to determine whether or not it was completely fused and integrated. The wavelength, total light transmittance, specific gravity, and refractive index of the cut-off point of this sample were measured in the same manner as in Example 1, and the results are shown in the table below.

Example 6 The polyamic acid solution obtained in Example 1 was poured into water to reprecipitate the polyamic acid, sufficiently stirred to remove the solvent, recovered, washed with methanol, and then dried under reduced pressure. The polyamic acid powder thus obtained is placed in a hot air drier for 25 minutes.
The mixture was heated to 0 ° C. for imidization. Then, it was pulverized to a fine powder.

Using the polyimide powder obtained as described above,
Hot-press molding was performed at a temperature of 300 ° C., a pressure of 1 t / cm ² , and a molding time of 30 minutes to produce a 1 mm-thick polyimide molded body. In this molded product, the powders were completely fused and integrated, and a homogeneous and transparent polyimide molded product was obtained.

About the polyimide molded body thus obtained,
The wavelength of the cut-off point, the total light transmittance,
The specific gravity and refractive index were measured and are shown in the table below. In addition, a pressurized car test was conducted in the same manner as in Example 1, and the results are shown in the same table.

Comparative Example 2 Using the polyamic acid solution obtained in Comparative Example 1, a polyimide powder was produced in the same manner as in Example 6.

Using the polyimide powder thus obtained, a 1 mm-thick polyimide molded body was produced in the same procedure as in Example 6. This molded product had large coloring and the powders were not completely fused and integrated.

About the polyimide molded body thus obtained,
The wavelength of the cut-off point, the total light transmittance,
The specific gravity and refractive index were measured and are shown in the table below.

[Example 7] The polyamic acid solution obtained in Example 2 was placed in a dish, placed in a vacuum dryer, dried under reduced pressure at a temperature of 25 ° C for 24 hours, and then irradiated with far-infrared rays while maintaining the state under reduced pressure. Use 10
Heat treatment was performed at 0 ° C. for 48 hours, at 150 ° C. for 48 hours, and finally at 250 ° C. for 24 hours to produce a 0.8 mm thick polyimide molded body.
This molded product was a homogeneous and transparent polyimide molded product.

About the polyimide molded body thus obtained,
The wavelength of the cut-off point, the total light transmittance,
The specific gravity and refractive index were measured and are shown in the table below. In addition, a pressurized car test was conducted in the same manner as in Example 1, and the results are shown in the same table.

Comparative Example 3 Using the polyamic acid solution obtained in Comparative Example 1, a polyimide molded body having a thickness of 0.8 mm was produced in the same manner as in Example 7. This molded product was homogeneous, but was a highly colored polyimide molded product.

About the polyimide molded body thus obtained,
The wavelength of the cut-off point, the total light transmittance,
The specific gravity and refractive index were measured and are shown in the table below.

In the following table, 6FDA is 2,2-bis (3,4-carboxyphenyl) hexafluoropropane dianhydride,
BPDA is 3,3 ', 4,4'-biphenyltetracarboxylic dianhydride, BFDA is 3,3', 4,4'-benzophenonetetracarboxylic dianhydride, 4,4'-DDS 4,4'-diaminodiphenylsulfone and 3,3'-DDS indicate 3,3'-diaminodiphenylsulfone, and 4,4'-DDE indicates 4,4'-diaminodiphenylether.

From the results in the above table, the example product has a very high total light transmittance and a small specific gravity as compared with the comparative example product. Furthermore, in the example product, since the wavelength of the cut-off point is just near the boundary point (380 nm) between the ultraviolet region and the visible light region,
It can be seen that the material is capable of absorbing ultraviolet light and transmitting most of visible light.

Example 8 An intraocular lens for a rabbit eye was manufactured using the polyimide molded body obtained in Example 7 to produce the lens unit 1 shown in FIG. 1, and using the polyvinylidene fluoride for the fixing unit 3. . The thus obtained intraocular lens was implanted in the anterior chamber of the rabbit eye, and the effect was examined for half a year.

Example 9 Using the polyimide molded body obtained in Example 7, as shown in FIGS. 3 and 4, a lens portion 1a and a fixing portion 3a
Were integrally formed to produce an intraocular lens 4 for rabbit eyes. The thus obtained intraocular lens 4 was embedded in the anterior chamber of the rabbit eye, and the effect was examined for half a year.

As a result, no toxicity and no harmful effects were observed in both the product of Example 8 and the product of Example 9. And
When the lens was taken out again and the optical characteristics were measured, both were exactly the same as before embedding.

[Brief description of the drawings]

1 is a plan view of an intraocular lens to be implanted in a posterior chamber of a human eye, FIG. 2 is a side view of FIG. 1, and FIG. 3 is an intraocular lens in which a lens unit and a fixing unit are integrally formed. FIG. 4 is a side view of FIG. 1,1a… Lens part, 2… Position adjustment hole 3,3a… Fixed part, 4… Intraocular lens

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Kiichiro Matsushita 1-1-2 Shimohozumi, Ibaraki-shi, Osaka Nippon Denko Corporation (72) Inventor Kazuhiko Nakata 3-7-17 Biwajima, Nishi-ku, Nagoya-shi, Aichi Prefecture No. Menicon Biwajima Research Laboratory Co., Ltd.

Claims (2)

(57) [Claims] 1. A lens comprising: a lens portion; and a fixing portion for fixing the lens portion in an eye. The lens portion is made of a colorless and transparent polyimide having a repeating unit represented by the following general formula (I) as a main component. An intraocular lens characterized by comprising: 2. The lens unit and the fixing unit are integrated, and both are made of a colorless and transparent polyimide having a repeating unit represented by the above general formula (I) as a main component. The intraocular lens according to (1).