U.S. patent number RE33,039 [Application Number 06/839,695] was granted by the patent office on 1989-08-29 for lens implant for insertion in the human eye.
Invention is credited to Eric J. Arnott.
United States Patent |
RE33,039 |
Arnott |
August 29, 1989 |
Lens implant for insertion in the human eye
Abstract
A lens implant for insertion in the posterior chamber of human
eye following an extra-capsular removal of the natural lens of the
eye comprises a lens 1 of polymethyl methacrylate with two similar
integral holding loops 2, which are flexible and resilient. Each
loop 2 has a relatively stiff radial portion 3 followed by more
flexible portions 5, 6 and 7 of varying curvatures. The free end 8
of each loop lies radially outwardly from the portion 5 of the
other loop and the loops are so shaped that when the ends 8 are
squeezed inwards into contact with the portion 5, the two loops 2
together form a substantially circular ring surrounding the lens
concentrically. This facilitates insertion of the lens through an
incision into the eye and, after insertion, the loops spring
outwards again and engage either the anterior capsular flaps
remaining after removal of the natural lens or the ciliary sulcus
to hold the lens in position in the eye.
Inventors: |
Arnott; Eric J. (London Win
9FD, GB2) |
Family
ID: |
10533467 |
Appl.
No.: |
06/839,695 |
Filed: |
March 13, 1986 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
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Reissue of: |
528337 |
Aug 31, 1983 |
04476591 |
Oct 16, 1984 |
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Foreign Application Priority Data
Current U.S.
Class: |
623/6.42 |
Current CPC
Class: |
A61F
2/16 (20130101); A61F 2/161 (20150401); A61F
2002/1683 (20130101) |
Current International
Class: |
A61F
2/16 (20060101); A61F 002/16 () |
Field of
Search: |
;623/6 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
Other References
American IOL International, Intraocular Lenses, (Advertisement).
.
American IOL International, 15542 Graham St., Huntington Beach, CA
92647, Style 130 & 130A Posterior Chamber Lenses, Dec. 29,
1981. .
American Medical Optics Model PC-80, Posterior Chamber (Knolle).
.
Intraocular Lenses, (Advertisement), 4 pp., Sep. 1982, American
Hospital Supply Corp., 1402 East Alton Ave., Irvine, CA 92714.
.
The Simcoe Posterior Chamber Lens, Feb. 1980, 4 pp. .
CILCO, advertising brochure, The Single-Piece Perspex Posterior
Chamber Lens, Mar. 1981, 2 pp. .
"Guide to Small-incision IOLS" by Dianne Herrin, Ocular Surgery
News, Nov. 15, 1988, vol. 6, No. 22, pp. 14 and 15. (RE
80.038)..
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Primary Examiner: Frinks; Ronald L.
Attorney, Agent or Firm: Brumbaugh, Graves, Donohue &
Raymond
Claims
I claim:
1. A lens implant for insertion in the posterior chamber of a human
eye after an extra-capsular extraction, said implant comprising a
lens .[.of polymethyl methacrylate.]. and first and second similar
holding loops formed integrally with and projecting from the
periphery of said lens, each of said loops lying substantially in
the plane of said lens and being open-ended with one end of said
loop integral with said lens and the other end of said loop free,
said ends of said loops which are integral with said lens being
substantially diametrically opposite each other around the
periphery of said lens, and each of said loops, starting from said
end which is integral with said lens, including a first portion
extending substantially radially outwards from said lens, a sharp
bend extending from said first portion, a second portion extending
from said bend, said second portion being of a curvature such that
.[.is.]. .Iadd.it .Iaddend.follows, but is spaced radially outwards
from, said periphery of said lens, a third portion which extends
from, and is of less curvature than, said second portion, and a
fourth portion which extends from said third portion and is of a
curvature substantially similar to that of said second portion, the
end of said fourth portion remote from said third portion being
free and lying radially outwards of .[.said second portion of.].
the other of said loops, whereby said two loops together surround
said lens, and said first portion of each of said loops being
relatively stiff and the other portions of said loops being more
flexible and resilient so that, in use, when said implant is to be
inserted through an incision into a human eye, said fourth portion
of each of said loops can be pressed inwards into contact with
.[.the second portion of.]. the other of said loops, and both said
loops bend in such a way that together they form a substantially
circular ring surrounding said lens, and, after insertion, said
loops spring open .[.again, but.]. .Iadd.and .Iaddend.the
configuration of an encircling ring is maintained and said ring
tends to adhere to the underlying posterior lens capsule of said
eye.
2. A lens implant as claimed in claim 1, in which said loops lie in
a flat plane, said plane containing the periphery of said lens.
3. A lens implant as claimed in claim 1, in which each of said
loops is of rectangular cross-section and of constant thickness
perpendicular to said plane, said first portion of each of said
loops being of greater width in said plane than said second, third
and fourth portions to provide said relative stiffness of said
first portion.
4. A lens implant as claimed in claim 3, in which the width of said
first portion of each of said loops tapers from said periphery of
said lens towards said second portion.
5. A lens implant as claimed in claim 3 or claim 4, in which the
width of the second portion of each of said loops tapers from said
first portion to said third portion, and said third portion and a
major part of said fourth portion are of constant width.
6. A lens implant as claimed in claim 1, in which the width of said
fourth portion of each of said loops is increased at said free end
thereof to form a wider free end part of said fourth portion and
both said wider end part of said fourth portion and said first
portion include means defining positioning holes therethrough, said
holes extending perpendicular to said plane. .Iadd.
7. A lens implant as claimed in claim 1, wherein the implant is
made of polymethyl methacrylate..Iaddend. .Iadd.8. A lens implant
as claimed in claim 1, wherein the fourth portion of each loop lies
radially outward from the second portion of the other loop such
that, in use, when the implant is to be inserted through an
incision into a human eye, said fourth portion of each loop can be
pressed inward into contact with the second portion of the other
loop..Iaddend.
Description
This invention relates to lens implants for insertion in the human
eye from which the natural lens has been removed with an
extra-capsular extraction.
Such lens implants consist of a lens made of polymethyl
methyacrylate (PMMA) having holding portions projecting from its
periphery to hold the lens in position in the eye between the
posterior capsule and the iris after the implant has been inserted
through an incision at the junction of the cornea and the sclera.
The holding portions are usually in the form of closed loops or
curved arms, which have one end free and are usually also known as
loops, lying in the plane of the lens. The loops are flexible and
resilient and in existing lens implants are of various shapes.
In most existing lens implants, the closed loops or curved arms are
made of Prolene, which is a polypropylene and are fixed to the
periphery of the lens. It has been found however that over a long
period of time the Prolene is subject to some bio-degradation and
if degradation takes place, there is a risk that the lens may
become displaced in the eye unless sufficient fibrous growth has
occured around it to hold it in place.
To overcome this problem attempts have been made to make the lens
with integral holding portions of PMMA which is not subject to
degradation. These integrally formed holding portions have been in
the form of tabs which lie in the plane of the lens and project
radially from its peripheryl. As these tabs are not able to bend in
the plane of the lens in the same way as is possible with the loops
or curved arms, they cannot spring outwards into contact with the
internal surface of the eye after they have been inserted and for
this reason they are not so successful as the loops or arms in
holding the lens accurately in position in the eye. Further, also
owing to the lack of flexibility in a radial direction in the plane
of the lens, they tend to cause greater difficulities in the
insertion of the implant through the incision in the eye than occur
with implants having holding portions in the form of flexible loops
or arms.
The aim of the present invention is to provide a lens implant for
insertion in the posterior chamber of a human eye after an
extra-capsular extraction, the implant comprising a lens with
holding portions of PMMA so that the problem of degradation is
overcome, and in which the holding portions are so formed that
insertion into the eye is facilitated while the maintenance of the
positioning of the implant in the eye is improved.
To this end, according to this invention, such a lens implant,
which comprises a lens of PMMA with two similar holding loops or
arms projecting from the periphery of the lens, each loop or arm
lying substantially in the plane of the lens and being open-ended
with one end fixed to the lens and the other end free, is
characterised in that the loops or arms are of PMMA and each has
one end formed integrally with the lens, the loops or arms being
substantially diametrically opposite each other around the
periphery of the lens, and each loop or arm, starting from the end
which is integral with the lens, has a first portion extending
substantially radially outwards from the lens, then extending
around a sharp bend into a second portion of a curvature such that
it follows, but is spaced radially outwards from, the periphery of
the lens, a third portion which extends from, and is of less
curvature than, the second portion, and a fourth portion which
extends from the third portion and is of a greater curvature,
substantially similar to that of the second portion, the end of the
fourth portion being free and lying radially outwards of the second
portion of the other loop or arm, so that the two loops or arms
together surround the lens, and the first portion of each loop or
arm being relatively stiff and the other portions being more
flexible and resilient so that, in use, when the implant is to be
inserted through an incision into the eye, the fourth portion of
each loop or arm can be pressed inwards into contact with the
second portion of the other loop or arm, and the two loops or arms
bend in such a way that together they form a substantially circular
ring surrounding the lens, and, after insertion, the loops or arms
spring open again but the configuration of an encircling ring is
maintained and the ring tends to adhere to the underlying posterior
lens capsule although a part of it may encroach on to the ciliary
sulcus. The encircling ring may act as a barrier protection against
the ingrowth of secondary lens fibres from the fornix of the human
lens. This will tend to prevent secondary clouding of the posterior
capsule which normally occurs some months after the cataract
extraction.
It has been found that by forming the lens with integral loops
having the configuration, which is commonly known as a D-shape even
though the straight part of the D is not present and the ends of
the curved part of the D are not connected to each other, and also
the relative stiffness of the different parts of the loops
described above, the implant as a whole can be inserted through the
incision in the eye and through the dilated iris into the posterior
chamber more easily than can be done with existing forms of lens
implant intended for insertion into the posterior chamber. After
insertion, the shapes and flexibility of the loops or arms are such
that the lens is held very securely in position regardless of
whether the radially outer parts of the loops contact the anterior
capsular flaps, which remain after removal of the anterior capsule,
or the ciliary sulcus in between the posterior capsule and the
iris.
The two loops or arms preferably lie in a flat plane which is the
plane containing the periphery of the lens, but they may
alternatively lie in the planes which are inclined to this plane by
a small angle of up to 10.degree. and it is this that is meant by
saying that the loops or arms lie substantially in the plane of the
lens.
Preferably each loop is of rectangular cross-section and of
constant thickness perpendeicular to the plane of the lens. The
first portion is then of greater width in this plane than the other
portions to provide its greater stiffness. The width of the first
portion tapers from the periphery of the lens to the beginning of
the second portion and preferably the width of the second portion
tapers from the first portion to the third portion. The third
portion and the major part of the fourth portion are then
preferably of constant width.
The width of the fourth portion of each loop is preferably
increased at its free end and both the wider free end part and the
first portion are preferably provided with positioning holes
extending through them perpendicular to the plane of the lens.
These positioning holes assist in moving the lens into the exact
required position after it has been inserted and, after insertion,
material of the eye tends to grow and penetrate through the holes
to anchor the lens implant more firmly in position.
The implant is preferably made, as is usual, of PMMA of CQ quality
and in one example the material is PMMA CQ 6, which is manufactured
by Imperial Chemical Industries Limited.
An example of a lens implant in accordance with the invention is
illustrated in the accompanying drawings in which:
FIG. 1 is a front elevation of the implant; and
FIG. 2 is a side elevation as seen from the left-hand side of FIG.
1.
The implant comprises a lens 1 and two holding loops 2 all of which
are formed integrally with each other of PMMA CQ 6 quality. Each of
the loops 2 has a first portion 3 which projects substantially
radially from the periphery of the lens 1 and is of substantial
width so that it is relatively stiff against bending in the plane
of the lens 1. The first portion 3 is connected around a sharp bend
4 to a second portion 5 which has a curvature such that it is
substantially concentric with the periphery of the lens 1. A third
portion 6, the curvature of which is substantially less than that
of the portion 5, extends from the portion 5 up to a fourth portion
7 which has the same curvature as the portion 5 so that the loop as
a whole is almost symmetrical about an axis lying in the plane of
the lens and perpendicular to the centre of the portion 6. The
portion 7 has its tip 8 widened and a positioning hole 9 is formed
in the widened tip 8. A second positioning hole 9 is formed in the
portion 3.
As can be seen most easily from FIG. 1, the portions 3 of the two
loops 2 are positioned diametrically opposite each other around the
periphery of the lens 1 and in consequence the loops 2, which are
the same as each other, are symmetrically disposed around the
lens.
The portions 5, 6 and 7 are flexible and resilient so that when the
loops 2 are bent in the plane of the lens with the portions 7 being
pushed towards the periphery of the lens, the tip 8 of one loop
will come into contact with the portion 5 of the other loop and the
two loops taken together form a ring, which is of generally
circular shape, extending around, but spaced from the periphery of
the lens 1. The loops are squeezed inwards into these positions to
enable the lens implant as a whole to be inserted into the
posterior chamber of the eye in front of the posterior capsule.
In this example, the lens 1, which is plano-convex as can be seen
from FIG. 2, has a diameter of 5.5 mm. Both the loops 2 have a
constant thickness of 0.14 mm perpendicular to the plane of the
lens. The portion 5 of each loop has a width of 0.22 mm adjacent
its junction with the portion 3 and the width tapers uniformly to
0.17 mm at the junction between the portions 5 and 6. The portions
6 and 7 have a constant width of 0.17 mm up to the widened tip 8.
The positioning holes 9 have a diameter of 0.4 mm. The maximum
overall dimension of the lens implant, that is the height as seen
in FIG. 1, is 13.5 mm and the minimum overall dimension, that is
the width as seen in FIG. 1, is 8.0 mm.
* * * * *