Coating processes – Medical or dental purpose product; parts; subcombinations;... – Implantable permanent prosthesis
Reexamination Certificate
2001-10-01
2003-08-26
Beck, Shrive P. (Department: 1762)
Coating processes
Medical or dental purpose product; parts; subcombinations;...
Implantable permanent prosthesis
C427S002100, C427S002310, C427S162000, C427S164000, C427S421100, C427S561000, C427S562000, C427S569000, C427S580000, C427S533000, C427S535000, C427S536000
Reexamination Certificate
active
06610350
ABSTRACT:
This application is based on Japanese Patent Application Nos. 2000-306155 filed Oct. 5, 2000, and 2001-239599 filed Aug. 7, 2001, the contents of which are incorporated hereinto by reference.
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a method of modifying or treating a surface of an ophthalmic lens. More particularly, the present invention is concerned with a method of modifying the ophthalmic lens surface by irradiating the ophthalmic lens surface with plasma generated at an atmospheric pressure, for thereby improving the properties of the ophthalmic lens surface such as wettability or hydrophilicity.
2. Discussion of Related Art
For assuring a lens user of excellent wear comfort of an ophthalmic lens such as a contact lens while eliminating a feeling of discomfort during wear of the ophthalmic lens, various techniques are proposed to modify a surface of the ophthalmic lens, for thereby improving wettability of the surface of the ophthalmic lens to attain a high degree of compatibility of the lens surface with the tear fluid of the eye, and the cornea surface of the eye.
Japanese Patent No. 2846343 discloses a method of giving wettability to a surface of an oxygen permeable hard contact lens, by subjecting the contact lens to a high-frequency glow discharge treatment at a reduced pressure in an atmosphere which does not include oxygen. JP-A-3-220519 discloses a method of improving wettability of a contact lens, by first subjecting a contact lens material to a discharge treatment at a normal or reduced pressure to generate free radicals on the surface of the contact lens material, and then effecting graft polymerization of N,N-dimethylacrylamide on the surface of the contact lens material on which the free radicals are generated.
The former method described above wherein the high-frequency glow discharge treatment is effected at a reduced pressure in an atmosphere not including oxygen, however, requires steps of replacing the ambient air in a container accommodating the contact lens, with the atmosphere which does not include oxygen, and evacuating the container after the contact lens has been accommodated therein. Accordingly, the disclosed method cannot utilize the ambient air for modifying the contact lens surface, and has a low degree of working efficiency, undesirably pushing up the cost of the surface modification of the contact lens. In the latter method, the contact lens material is initially subjected to the discharge treatment, and subsequently to the graft polymerization, so that the process steps for modifying the surface of the contact lens material are more complicated than those in the former method. Further, the cost of manufacture of the contact lens is inevitably increased.
It is known that the discharge treatment (plasma treatment) described above assures a sterilizing effect as well as improved wettability. JP-A-8-156920 discloses a method of sterilizing a subject formed of a synthetic or a natural high-molecular material by a glow discharge treatment at an atmospheric pressure while the subject is interposed between the electrodes which are opposed to each other. This method attains effective sterilization with respect to bacteria and spores.
Even if the above-described sterilizing method is applied to the ophthalmic lens for simultaneously modifying and sterilizing the ophthalmic lens surface, it requires a cumbersome step of iteratively disposing the subjects (contact lenses) to be treated in a limited space defined by and between the electrodes for effecting the discharge treatment on the subjects, making it difficult to modify, in a short period of time, the surfaces of the contact lenses which are mass-produced. Further, the above-described sterilizing method may cause insufficient modification of the contact lens surfaces since the treatment is effected in the atmosphere between the electrodes. Moreover, the contact lens surfaces may not be uniformly modified due to a variation of the density of the plasma gas to which the contact lenses are exposed.
SUMMARY OF THE INVENTION
The present invention was developed in the light of the background art situations described above. It is therefore an object of the present invention to provide a method of modifying a surface of an ophthalmic lens by contacting the surface of the ophthalmic lens with plasma generated at an atmospheric pressure, wherein the ophthalmic lens surface can be uniformly modified with high degrees of working efficiency and economy without damaging the ophthalmic lens.
The object indicated above may be achieved according to a first aspect of the present invention, which provides a method of modifying a surface of an ophthalmic lens, including the steps of: generating plasma at an atmospheric pressure; and contacting the ophthalmic lens with the plasma for modifying the surface of the ophthalmic lens.
In the present method indicated above wherein the plasma is generated at an atmospheric pressure and the ophthalmic lens is brought into contact with the plasma, the surface of the ophthalmic lens can be modified so as to improve its wettability or hydrophilicity without evacuating the container in which the ophthalmic lens is accommodated, for thereby significantly improving the working efficiency while decreasing a time and a cost required for modifying the ophthalmic lens surface. Further, the present method does not require any equipment (e.g., gas conduit and working gas) for replacing the ambient air in the container with a suitable atmosphere resulting in reduction of an equipment cost.
In one preferred form of the above-indicated first aspect of the present invention, the step of contacting the ophthalmic lens with the plasma comprises a step of blowing the plasma onto the ophthalmic lens through at least one opening of a plasma control member which is spaced apart from the surface of the ophthalmic lens.
In one advantageous mode of the above preferred form of the first aspect of the invention, the plasma control member has a matrix of a multiplicity of openings. Preferably, the plasma control member is a network which has a matrix of a multiplicity of openings each having a size of 0.3~15 mm. The network is preferably a wire framework consisting of a plurality of wires each having a diameter of 0.1~3 mm. Preferably, the plasma control member is a planar member which has a matrix of a multiplicity of perforations formed through a thickness thereof. The planar member preferably has an opening ratio of 15~70%, and is a sheet member which has perforations formed by punching and which has a thickness in a range of 0.1~3 mm.
The object indicated above may be achieved according to a second aspect of the invention, which provides a method of modifying a surface of an ophthalmic lens, including the steps of: generating plasma at an atmospheric pressure between electrodes of a plasma generating device; and blowing the plasma from the plasma generating device by introducing a gas between the electrodes, so as to irradiate the ophthalmic lens located outside the plasma generating device with the plasma blown out from the plasma generating device for modifying the surface of the ophthalmic lens.
In the present method described above, the ophthalmic lens to be treated is disposed outside the electrodes of the plasma generating device, and the plasma generated at an atmospheric pressure between the electrodes is forced to be blown onto the ophthalmic lens by introducing a gas between the electrodes. This arrangement eliminates the conventionally required cumbersome step of iteratively disposing a predetermined number of ophthalmic lenses within a limited space between the electrodes, resulting in a speedy treatment of the ophthalmic lens. Accordingly, the present method assures high efficiency and economy in modifying the ophthalmic lens surface.
The present method wherein the plasma generated between the electrodes is blown onto the ophthalmic lens by the gas introduced between the electrodes is unlikely to suffer from variation in the density of plas
Gotou Yuuji
Nakada Kazuhiko
Suzuki Hiroaki
Beck Shrive P.
Burr & Brown
Kolb Michener Jennifer
Menicon Co. Ltd.
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