Surgery – Instruments – Means for removing – inserting or aiding in the removal or...
Reexamination Certificate
1999-08-12
2002-03-12
Truong, Kevin (Department: 3731)
Surgery
Instruments
Means for removing, inserting or aiding in the removal or...
Reexamination Certificate
active
06355046
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an insertion device for inserting a deformable intraocular lens into the eye. Examples of such a deformable intraocular lens include a deformable intraocular lens that is inserted into the eye in place of the natural lens when the latter is physically extracted because of cataracts, and a vision correction lens that is inserted into the eye for the sole purpose of vision correction.
2. Description of the Related Art
Implantation of an intraocular lens for treating cataract has been widely performed since 1949, when Ridley implanted for the first time an artificial lens, i.e., intraocular lens into the human eye in place of an opaqued natural lens during cataract surgery.
The intraocular lens used first had an optical portion made of polymethyl methacrylate (PMMA). The implantation of the intraocular lens was accompanied by complications which occurred after the cataract surgery. Many ophthalmologists have shown interest in the complications and have studied them. As a result, most of the problems have been solved. However, since the optical portion is made of a hard material, an incision for implantation of such an intraocular lens must have a dimension somewhat greater than the diameter of the optical portion. Since an incision to be formed in the eyeball is large, in the degree of astigmatism after surgery increases due to suture of the incision.
A method of surgery has been pointed out as a cause of the above-mentioned complications. That is, the conventional surgery for extracting a natural lens because of cataract has been performed by using an ECCE (extracapsular cataract extraction) operation technique in which a lens is extracted without crushing it. Since this operation technique has required formation of an incision of about 10 mm, the operation caused astigmatism quite often. To solve this problem, a technique called pharmacoemulsification (PEA) using an ultrasonic emulsification/suction apparatus has been developed recently. In this method, an opaqued natural lens is crushed and emulsified using ultrasonic waves emitted from a cylindrical ultrasonic chip, and is sucked for extraction. When this method is used, the size of an incision formed in the eyeball can be decreased to a size sufficient for insertion of the cylindrical ultrasonic chip. A crushed lens can be extracted through an incision of about 3 to 4 mm. Therefore, this method makes it possible to perform the extraction operation by forming only a small incision, which mitigates the astigmatism after the operation. However, since the optical portion is made of a hard material, an incision for implantation of such an intraocular lens must have a dimension somewhat greater than the diameter of the optical portion, as mentioned above. In the case of a standard intraocular lens having an optical portion of 6.0 mm, an incision having a size equal to or greater than 6.5 mm must be formed. Therefore, even if an opaqued natural lens is extracted through a small incision using pharmacoemulsification, the incision must be widened so as to insert an intraocular lens. Accordingly, the problem of astigmatism occurring after surgery due to the large incision has not been solved.
In order to mitigate astigmatism after surgery, improved intraocular lenses have been developed which can decrease the size of incisions. Examples of such improved lenses include an intraocular lens having an oval optical portion which is inserted into an incision such that its smaller radius is oriented in the direction of the incision, and an intraocular lens with an optical portion having a reduced diameter. However, each of these intraocular lenses still has a hard optical portion. Therefore, employment of these intraocular lenses decreases the incision size only to about 5.5 mm (i.e., only by about 1 mm).
In order to solve the above-described fundamental problems, intraocular lenses themselves have been improved recently. Such an improved intraocular lens is disclosed in Japanese Patent Application Laid-Open (kokai) No. 58-146346. In the intraocular lens, at least an optical portion is made of a deformable elastic material having a predetermined memory characteristic. Alternatively, at least an optical portion is made of an elastic material having a predetermined memory characteristic, and supports are provided which are made of a material different from that of the optical portion and are adapted to support the optical portion within an eye. Moreover, as disclosed in Japanese Patent Application Laid-Open (Kokai) Nos. 58-146346, 4-212350, 5-103803, 5-103808, 5-103809, and 7-23990 improved insertion tools have been proposed. Using these tools, the optical portion of an intraocular lens is compressed, rolled, bent, stretched, or folded so as to reduce its exterior size, thereby making it possible to insert the intraocular lens through a small incision. These intraocular lenses and insertion tools therefor make it possible to perform surgery by forming only a small incision, thereby mitigating astigmatism after surgery.
FIGS. 32
to
35
show the conventional deformable intraocular lenses. The deformable intraocular lens shown in
FIG. 32
is composed of a circular optical portion
2
and two symmetrically disposed supports
3
. The circular optical portion
2
is made of an elastic material having predetermined memory characteristics. The supports
3
are made of a material different from that of the optical portion
2
, and the bases
3
a
of the supports
3
are embedded in the peripheral region of the optical portion
2
for fixing, while the wire-shaped tails
3
b
are curved. The optical portion
2
has on the periphery thereof projections
2
a
for reinforcing the positions where the base
3
a
of the supports
3
are embedded. The deformable intraocular lens
1
shown
FIG. 33
is configured in the same manner as is the deformable intraocular lens of
FIG. 32
except that the projections
2
a
are omitted. Each of the deformable intraocular lenses shown in
FIGS. 34 and 35
is composed of a circular optical portion
2
and a pair of thin plate-shaped support portions
4
that are integral with the optical portion
2
. The optical portion
2
, like the optical portion
2
shown in
FIG. 32
, is made of an elastic material having predetermined memory characteristics. The support portions
4
are projected from the periphery of the optical portions
2
in opposite directions.
An insertion device disclosed in, for example, Japanese Patent Application Laid-Open (kokai) No. 7-23991 is used for deformable intraocular lenses, as shown in
FIGS. 32
to
35
, each of which is composed of the optical portion
2
and the support portions
3
or
4
, of which at least the optical portion
2
has predetermined memory characteristics. The deformable intraocular lens
1
is folded in order to reduce its exterior size and is advanced along an insertion tube having, for example, a cylindrical shape, in order to be inserted into the eye through an incision formed in the eyeball.
FIGS.
26
(
a
),
26
(
b
) and
27
show the structure and operation of the conventional insertion device. First, an enclosing member
5
of the insertion device having a hinge portion
6
is opened. A deformable intraocular lens is placed on a lens receiving section
7
such that the lens engages grooves
9
a
and
9
b.
Subsequently, the enclosing member
5
is closed so as to reduce the exterior size of the deformable intraocular lens and hold it. The grooves
9
a
and
9
b
become shallower toward the insertion-tube side of the lens receiving section
7
. However, the grooves
9
a
and
9
b
extend up to the rear end of the lens receiving section
7
while maintaining constant depth. Since the grooves
9
a
and
9
b
converge at the front side with respect to the direction along which the lens is pushed out, the position where the lens is to be placed can be determined with reference to the converged portions. However, since the grooved structure continues unchanged to the rear end, no refe
Kikuchi Toshikazu
Kobayashi Ken-ichi
Masuda Takashi
Nakajima Toshiyuki
Canon Staar Co. Inc.
Ladas & Parry
Truong Kevin
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