Contact lens

Details Contact lens Contact lens

1991-05-29

1993-03-16

Schofer, Joseph L.

Synthetic resins or natural rubbers -- part of the class 520 ser

Synthetic resins

Polymers from only ethylenic monomers or processes of...

526279, 526245, C08F 1820, C08F 2024, C08F 3008

Patent

active

051945428

DESCRIPTION:

BRIEF SUMMARY
TECHNICAL FIELD

This invention relates to a contact lens, and more specifically, it relates to a rigid contact lens, i.e. a so-called "hard contact lens" having oxygen permeability.


TECHNICAL BACKGROUND

At the present time, contact lenses generally used are largely classified into hard contact lenses and soft contact lenses.
As a hard contact lens, an oxygen-permeable hard contact lens is recently proposed which is formed of a copolymer containing, as main components, a silicone-containing (meth)acrylate ["(meth)acrylate" in the present specification stands for both of acrylate and methacrylate] and a fluorine-containing (meth)acrylate. A contact lens of this type is disclosed in Japanese Patent Unexamined Publication No. 63-159820. The contact lens disclosed in this Unexamined Publication is formed of a copolymer containing, as main components, at least one fluoromethacrylate of the following general formula, ##STR1## wherein R.sub.f is --CH(CF.sub.3).sub.2, --CH.sub.2 CH(CF.sub.3).sub.2 or --(CH.sub.2).sub.2 C.sub.n F.sub.2n+1 (n=2-10), and siloxanyl methacrylate. With this contact lens, a sufficient effect on oxygen permeability is obtained.
However, the contact lens disclosed in the above Japanese Patent Unexamined Publication 63-159820 has not been fully satisfactory with regard to hardness. And, the contact lens disclosed in the above Unexamined Publication cannot be said to have sufficient water wettability, although a hydrophilic monomer is used to improve the water wettability. Further, this contact lens has a possibility that when the amount of the hydrophilic monomer is increased to improve the water wettability, the compatibility among this monomer and other monomer(s) decreases, and the resultant polymer therefore undergoes phase separation to become opaque.
As a method of improving the water wettability, it is also proposed to impart a lens surface with hydrophilic nature. Since, however, a hydrophilic nature-imparting layer is very thin, the layer is liable to peel or disappear, and it is often required to treat the lens surface again.
This invention has been made to provide a novel oxygen-permeable contact lens which overcomes the above problems, and it is an object of this invention to provide an oxygen-permeable hard contact lens which has not only suitable oxygen permeability required to actually fit it on but also hardness to fully endure fracture or damage in the ordinary handling and further, which is excellent in water wettability and a sense of fitting it on.


DISCLOSURE OF THE INVENTION

This invention has been made in order to achieve the above object, and the contact lens of this invention is formed of a copolymer obtained by copolymerizing a monomer mixture containing, as essential components, a fluorine-containing monomer of the general formula (I), ##STR2## wherein X is H or CH.sub.3, Y is --CH.sub.2 --CH.sub.2 O--, --CH.sub.2 CH.sub.2 CH.sub.2 O, ##STR3## and n is 1, 2 or 3, siloxanyl (meth)acrylate, alkyl (meth)acrylate, a hydrophilic monomer and a crosslinking agent.


PREFERRED EMBODIMENTS OF THE INVENTION

The fluorine-containing monomer used in this invention is represented by the following general formula (I). ##STR4## wherein X is H or CH.sub.3, Y is --CH.sub.2 --CH.sub.2 O--, --CH.sub.2 CH.sub.2 CH.sub.2 O--, ##STR5## and n is 1, 2 or 3.
Examples of the fluorine-containing monomer of the general formula (I) are as follows. ##STR6##
The fluorine-containing monomers of the above group improve oxygen permeability of a contact lens due to a perfluorooctyl group contained, facilitate dispersibility of siloxanyl (meth)acrylate (to be referred to as "Si(M)A" hereinafter) due to its excellent compatibility therewitt, and further, contribute to development of higher oxygen permeability. The oxygen atom adjacent to the ethylene group bonded to the perfluorooctyl group plays a part in imparting hydrophilic nature and providing a good fitting sense. Further, since the ethylene group bonded to the perfluorooctyl group exhibits resistance to hydrolysis caused by water and othe

REFERENCES:
patent: 4566981 (1986-01-01), Howells
patent: 4829137 (1989-05-01), Stoyan

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