GB1577825A - Intraocular lens - Google Patents

Description

(54) INTRAOCULAR LENS (71) We, AMERICAN OPTICAL COR PORATION, a corporation organized under the laws of the State of Delaware, United States of America, of 14 Mechanic Street, Southbridge, Massachusetts, United States of America, do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement: This invention is concerned with intraocular lenses, more particularly such lenses having wire secured thereto for fixing the lenses in place.

In the manufacture of wire, a lubricant is usually used to prevent sticking and galling in the dies and it is customary to use a relatively soft metal cladding as the lubricant in cases where liquid lubricants are known to be unreliable. Such is the case with titanium wire which, because of its low density and biocompatability, is ideally suited for fixing artificial intraocular lenses (pseudophakoi) in place. The use of liquid or chemical lubricants does not overcome the tendency for titanium to stick and gall in drawing dies.

Claddings used heretofore to lubricate titanium have been base metals such as nickel and copper which require complete removal from the finished wire before use in the body. Not being biocompatible and accordingly potentially toxic or infective, the nickel or copper claddings are stripped with acid which involves tedious, time consuming and costly operations requiring careful monitoring for assurance of complete removal of the base metal.

We have now found that noble metals are effective lubricants for use in the drawing of titanium wire and are biocompatible so that claddings of them to not have to be removed from the finished wire before intraocular use.

According to the present invention, therefore, there is provided an intraocular lens having wire secured thereto for fixing the lens, in place, the wire consisting of a core of titanium having a noble metal cladding thereon.

The wire is preferably made by tightly fitting a tube of noble metal upon a titanium rod and drawing the resulting composite into wire.

The thickness of the noble metal cladding is preferably kept as low as possible, that is the cladding preferably forms not more than 5% of the cross-sectional area of the wire, so that the advantage of the low density of titanium is not appreciably adversely affected by the added cladding.

In the following description, reference will be made to the accompanying drawings, in which: Figure 1 is an illustration of an exemplary artificial intraocular lens (pseudophakos) in accordance with the invention, and Figure 2 is a greatly enlarged crosssectional view taken on line 2-2 of Figure 1.

Figure 1 of the drawings illustrates a typical pseudophakos 10 comprised of a lens 12 having loops of wire 14 secured thereto for use in fixing the pseudophakos in place within the eye of an aphakic.

For the purpose of minimizing the weight of the pseudophakos 10, the lens 12 is preferably formed of a lightweight polymer, such as polymethyl methacrylate, and wires 14 are formed of a durable shape-retaining lightweight material. This material, according to the present invention, is titanium, which is noted for its exceptionally low density, having a noble metal cladding.

While pseudophakos 10 is of the type traditionally used for iridocapsular implantation, it should be understood that it has been selected only for purposes of illustrating the applicability of the present invention to intraocular use. The illustration is not intended to restrict the invention to any particular type or construction of pseudophakos and/or other prosthesis. Those interested in further details of intraocular prostheses may refer to U.S. Patents Nos.

3,971,073; 3,996,626; 4,012,823; and 4,014,049; there being various other types and forms of prosthetic device which may benefit from the present invention.

According to the invention the traditional base metal cladding of nickel or copper which has been used to lubricate titanium for drawing into wire is replaced by a thin cladding of a noble metal or noble metal alloy which is biologically inert, i.e. noninfective and non-receptable when implanted under the traditional sterile conditions of surgery.

The cladding and wire drawing operation may be performed with conventional apparatus and/or procedure well known to those skilled in the art and requiring no description herein. Those interested in details of suitable wire drawing systems may refer to Metals Handbook, (1948), pages 357 to 360; 1101 and 1102.

Referring more particularly to Figure 2, it can be seen that wire 14 comprises a core or main body 16 of titanium having cladding 18 which, in a preferred form of the invention, occupies less than 5% of the cross- sectional area of the wire 14. Thus, the weight of the cladding 18 is negligible and the advantage of low density afforded by the titanium 16 is substantially unaffected by the cladding 18.

In a preferred embodiment of the wire 14, the cladding 18 consists of pure platinum or a platinum alloy, such as 90% platinum and 10% iridium, or pure gold or any of the number of noble metals known to metallurgists as being in the platinum or gold families and/or alloys thereof.

Wire 14 is suitably made by providing a titanium rod of approximately 6 mm to 13 mm diameter with a tight fitting tube of platinum or platinum alloy or other noble metal of such wall thickness that approximately 5% of the cross-sectional area of the composite comprises the tube. The assembly is then rolled to a reduced diameter of approximately 3 mm and drawn in the normal manner to a size of from 0.025 mm to 0.25 mm diameter. A wire size conventionally used in pseudophakoi is 0.127 mm diameter.

The wire thus formed may then be cut to length, shaped by bending and secured to the lens of the pseudophakos without further processing, i.e. without stripping of the cladding. The noble metal cladding having performed its function as a soft metal lubricant permitting drawing of the titanium without sticking or galling is allowed to remain intact. It is biocompatible and its contribution to the weight of the titanium wire is negligible.

WHAT WE CLAIM IS:- 1. An intraocular lens having wire secured thereto for fixing the lens in place, the wire consisting of a core of titanium having a noble metal cladding thereon.

2. A lens according to claim 1, in which the cladding forms not more than 5% of the cross sectional area of the wire.

3. A lens according to claim 1 or 2, in which the noble metal is platinum or a platinum alloy.

4. A lens according to claim 3, in which the platinum alloy is an alloy of approximately 90% platinum and approximately 10% iridium.

5. A lens according to claim 1 or 2, in which the noble metal is gold.

6. A lens according to any of claims 1 to 5, in which the wire is made by tightly fitting a tube of the noble metal upon a titanium rod and drawing the resulting composite into wire.

7. A lens according to claim 6, in which the composite is rolled to a reduced crosssectional area prior to drawing.

8. A lens according to claim 6 or 7, in which the wire is drawn to a diameter of 0.025 to 0.25 mm.

9. A lens according to claim 1, substantially as described herein with reference to the accompanying drawings.

**WARNING** end of DESC field may overlap start of CLMS **.

Claims (9)

**WARNING** start of CLMS field may overlap end of DESC **. 4,014,049; there being various other types and forms of prosthetic device which may benefit from the present invention. According to the invention the traditional base metal cladding of nickel or copper which has been used to lubricate titanium for drawing into wire is replaced by a thin cladding of a noble metal or noble metal alloy which is biologically inert, i.e. noninfective and non-receptable when implanted under the traditional sterile conditions of surgery. The cladding and wire drawing operation may be performed with conventional apparatus and/or procedure well known to those skilled in the art and requiring no description herein. Those interested in details of suitable wire drawing systems may refer to Metals Handbook, (1948), pages 357 to 360; 1101 and 1102. Referring more particularly to Figure 2, it can be seen that wire 14 comprises a core or main body 16 of titanium having cladding 18 which, in a preferred form of the invention, occupies less than 5% of the cross- sectional area of the wire 14. Thus, the weight of the cladding 18 is negligible and the advantage of low density afforded by the titanium 16 is substantially unaffected by the cladding 18. In a preferred embodiment of the wire 14, the cladding 18 consists of pure platinum or a platinum alloy, such as 90% platinum and 10% iridium, or pure gold or any of the number of noble metals known to metallurgists as being in the platinum or gold families and/or alloys thereof. Wire 14 is suitably made by providing a titanium rod of approximately 6 mm to 13 mm diameter with a tight fitting tube of platinum or platinum alloy or other noble metal of such wall thickness that approximately 5% of the cross-sectional area of the composite comprises the tube. The assembly is then rolled to a reduced diameter of approximately 3 mm and drawn in the normal manner to a size of from 0.025 mm to 0.25 mm diameter. A wire size conventionally used in pseudophakoi is 0.127 mm diameter. The wire thus formed may then be cut to length, shaped by bending and secured to the lens of the pseudophakos without further processing, i.e. without stripping of the cladding. The noble metal cladding having performed its function as a soft metal lubricant permitting drawing of the titanium without sticking or galling is allowed to remain intact. It is biocompatible and its contribution to the weight of the titanium wire is negligible. WHAT WE CLAIM IS:-

1. An intraocular lens having wire secured thereto for fixing the lens in place, the wire consisting of a core of titanium having a noble metal cladding thereon.

2. A lens according to claim 1, in which the cladding forms not more than 5% of the cross sectional area of the wire.

3. A lens according to claim 1 or 2, in which the noble metal is platinum or a platinum alloy.

4. A lens according to claim 3, in which the platinum alloy is an alloy of approximately 90% platinum and approximately 10% iridium.

5. A lens according to claim 1 or 2, in which the noble metal is gold.

6. A lens according to any of claims 1 to 5, in which the wire is made by tightly fitting a tube of the noble metal upon a titanium rod and drawing the resulting composite into wire.

7. A lens according to claim 6, in which the composite is rolled to a reduced crosssectional area prior to drawing.

8. A lens according to claim 6 or 7, in which the wire is drawn to a diameter of 0.025 to 0.25 mm.

9. A lens according to claim 1, substantially as described herein with reference to the accompanying drawings.