Note: Descriptions are shown in the official language in which they were submitted.
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M~ETI~OD AND INTRA-SCLERA >rMPLANT FO)EZ
T,I~tEATMENT OF GLAUCOMA, A1~D PRESB'YOPrA
Background of Invention
1. )Field of Invention
This application claims the benefit of U.S. provisional Application No.
60/310,027 filed
08/03/01.
The disclosed device relates to a scleral implant. More particularly it
relates to a device
which is implanted in the sclera of the eye for the treatment of excess
intraocular pressure which
~frequently accompanies ~'rlaucoma and for the treatment of presbyopia or loss
of accommodation
of the eye.
Glaucoma is an a a disease wherein the patient gradually loses sight. Such
vision loss is
caused by damage to the ptic nerve which acts like an electric cable and
communicates images
from the eye to the brain_~ High intraocular pressure frequently accompanies
Glaucoma and is
one of the zx~ain causes of the nerve damage causing this vision loss. la is
thought that increased
intraocular pressure is cased when the eye's drainage canals become clogged
over time_ The
ir~traocular pressure rises to levels causing damage because the correct
amount of fluid can't
drain out of the eye in th ~aormal fashion. If this excess intraocular
pressure is not detected and
treated, it can cause a gradual loss of vision. Sucb a vision Loss in some
cases occurs over a
long period of time. However, in some cases of glaucoma the eye pressure
usually rises very
. fast. ~t is thought that this happens when the eye drainage canals are
blocked oar covered over,
like the clog in a sink when something is covering the drain.
. Drugs are freduez~tly used on cases where intraocular pressure slowly builds
and
frequently work well. Xnlpatients suffering a rapid rise in such pressure or a
long term rise that
has reached a dangerous lateau, severe eye damage and permanent loss of sight
can result.
Surgery has also been used more recently to treat intraocular pressure.
Clinical
investigators have noted in recent years that intraocular pressure is louvered
following radial
incisions in the anterior sl lera, known as an anterior ciliary sclerotom~y.
1'JnfortunatEly, for
patients undergoing such a procedure, the beneficial effects arc negated over
a period of tizx~e
Following the procedure as the incisions heal and scar_ Consequently the
potential for eyesight
loss arises as pressure ag~un builds follov~ing the surgery.
Another sight related problem affecting patients is that of Presbyopia which
is a vision
condition in which the crystalline lend Qf ~ pyj~di'~ gyp iQ5G5 iC5
~~r?((~?111Cy. Tr~IS 1055 0~
SUBSTITUTE SHEET (RULE 26)
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flexibility makes it difficult for a person to focus on close objects. While
Presbyopia may seem
to occur suddenly once the patient discovers the problem, it is generally
accepted that the cause
of the sight loss is actual loss of flexibility of the lens which takes place
over a number of years
and usually becomes noticeable in the early to mid-forties.
Treatment to help you compensate for presbyopia includes prescription reading
glasses,
bifocals, contact lenses, and laser surgery. However such corrective lenses
can be inconvenient
to the wearer and laser surgery to the lens of the eye carries with it the
inherent risk to the
eyesight itself if a mistake is made.
Still further, many diseases that attack the eye and eyesight require the long
term
administration of drugs to maintain eyesight. It is desirable to provide an
easily placed device
that would provide long term modulated direct communication of drugs into the
eye
concurrently with helping correct the internal pressure and possible vision
problems of the
patient.
Consequently, there is a continuing need for a medical treatment that would
require
simple surgical procedure that would have long-lasting effects to relieve
internal eye pressure
and for the correction of presbyopia to eliminate or reduce the need for
prescription lenses and
without risky surgery on the lens of the eye itself. Such a treatment would be
further enhanced
by the provision of a drug delivery system that can be modulated for dose and
time that would
aid in internal pressure relief as well as other eye ailments requiring
precision or long term
delivery of drugs.
2. PRIOR ART
Surgical procedures and implantable devices have recently been developed to
address the
presbyopia.
U. S. Patent No. 6,280,468 (Schachar) discloses a scleral prosthesis for
treatment of
presbyopia and other eye disorders. Schachar teaches the placement of a
prostheses in a plurality
of pockets slightly smaller than the implant, circumferentially around the
pupil, to exert an
outward pressure on the sclera thereby restoring the working distance of the
ciliary muscle
allowing the patient relief from presbyopia. However, Schachar is oriented
circumferentially
around the pupil or front of the eye and lacks an anchoring means to hold the
implants in proper
position in the sclera over the long term which can result in shifting of the
implant reducing or
eliminating its effectiveness. Further, the use of tunnels smaller than the
implant tends to cause
broken implants. Schachar also lacks a drug delivery means from the implant.
Still further,
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actual dismounting of the implant can occur which would require removal from
the eye
especially if it pierces the outside surface of the eye when shifting in
position. Additionally, the
circumferential placement of the implants is not as effective at encouraging
internal drainage and
reduction of intraocular pressure.
U.S. Patent No. 6,102,045 (Nordquist) discloses a method and apparatus for
lowering
intraocular pressure of the eye. However Nordquist is a filtering implant
which extends into the
anterior chamber of the eye through an opening in the limbus cornea. Nordquist
lacks the ability
to correct presbyopia that a sclera-mounted device provides and because of its
delicate
positioning and communication directly with the anterior chamber Nordquist is
harder to
position correctly. It also lacks the ability to infuse drugs to the eye and
the provision of direct
communication between the anterior chamber and the exterior regions of the eye
increases the
risk of infection to the anterior chamber.
U.S. Patent No. 6,079,417 (Fugo) discloses a method and device for reshaping
the cornea
to change its topography. However Fugo lacks the ability to increase the
drainage from the eye
interior to lower intraocular pressure. Fugo also is designed to mount
directly into the cornea
layer of the eye.
U. S. Patent No. 5,178,604 (Baerveldt) teach the use of an implant for
increasing eye
drainage and reduce pressure caused by glaucoma. However Baerveldt is simply a
tube which
communicates directly with the interior chamber of the eye and offers no aid
to rectifying
presbyopia.
As such, there is a continuing need for a reliable operative method and
prostheses that
will aid physicians in interrupting the relentless cycle that results in
vision loss and eye damage
to patients suffering from building intraocular pressure in the eye. Such a
device should be
insertable into the eye in a relatively easy procedure for a trained surgeon.
Such a device and
procedure should avoid the more delicate structures of the eye and should also
avoid
communicating internal eye structures directly with the exterior of the eye to
prevent infection.
Such a device would provide additional utility by through the optional ability
to provide a drug
delivery system from the implant directly to the eye. Still further, the
device implanted by this
method should be dimensioned with an anchor structure to insure that the
implant stays properly
positioned in perpetuity thereby alleviating the need for replacement or
removal caused by
dislocatable implants and maintaining a fixed correction of vision.
SUMMARY OF THE INVENTION
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The above problems, and others are overcome by the herein disclosed method and
intra-
sclera implant for the treatment of glaucoma and presbyopia. The method of
insertion of the
implants requires incisions be made radially in the anterior sclera. A
plurality of such incisions
are made radially and only into the sclera with the current best number of
incisions being four,
with one incision in each quadrant of the eye.
Once the incisions are made in the proper quadrants and extend properly toward
the rear
of the eye, one implant is positioned within the space of each of the
incisions. The scleral
incision is then closed by opposition or using suture or other means of
closure of the incision to
urge the scleral flap toward the surface of the eye from where it was detached
and reattach it to
the sclera.
The implant is currently best formed in a unitary construction and formed of a
material
that is inert when in contact with body tissue. Favored materials include one
or a combination
of materials from a group including hydroxiapartite, silicone,
polymethylmethacrylate, acrylic,
and tantalum.
The unitary body of the implant can optionally be serrated or have one or a
plurality of
apertures running through to contact scleral tissue and anchor it.
Additionally, the body of the
implant can also be impregnated with a drug which thereafter would be slowly
delivered into the
tissue of the eye or have an internal reservoir or coating of a slowly
disburseable drug that can be
modulated for dose and time frame to allow for long term delivery of
medication to the eye and
body of the patient, from the implant.
Accordingly, it is the object of this invention disclosed herein to provide a
reliable
method of surgery for the placement of implants in the sclera is easy to
accomplish for the
trained surgeon.
It is another object of this invention to provide an implant that is easily
insertable into the
scleral layer of the eye during a surgical procedure.
It is still another object of this invention to provide such an implant that
has an anchoring
system to insure that the implant maintains the position intended by the
surgeon implanting it.
Yet another object of this invention is the provision of a method and
apparatus for eye
surgery that may be used to treat presbyopia as well as rising intraocular
pressure.
Still further, it is an object of this invention to provide such an implant
with the option of
long term drug delivery directly from the implant to the eye.
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These and further objectives of this invention will be brought out in the
following part of
the specification, wherein detailed description is for the purpose of fully
disclosing the invention
without placing limitations thereon.
BRIEF DESCRIPTION OF THE DRAWING FIGURES
The accompanying drawings which are incorporated in and form a part of this
specification illustrate embodiments of the disclosed device and together with
the description,
serve to explain the principles of the invention.
Figure 1 depicts the placement of a plurality of implants radially in four
quadrants of the
eye and the steps of the method to do so.
Figure 2 shows the implant and its placement in the scleral layer of the eye.
Figure 3 depicts a preferred embodiment of the implant showing anchors and
optional
coating.
Figure 4 depicts another preferred embodiment of the device having an internal
reservoir
for holding a drug to be communicated to the exterior.
Figure 5 depicts another preferred embodiment of the device showing anchors
about the
exterior.
Figure 6 depicts another preferred embodiment of the device showing a round
body and
anchors extending from the surface.
DETAILED DESCRIPTION OF THE PREFERRED
EMBODIMENTS OF THE DISCLOSED DEVICE
Referring now to figures 1-6 depicting the preferred embodiments of the
disclosed device
10, figure 1 depicts the preferred location and steps in the operative method
for the placement of
the device 10 into the eye 12. The method for surgical insertion of the
implant device 10
requires incisions be made radially in the sclera 16 in relation to the cornea
22 and generally in
line with the center axis 14 of the eye 12 depicted as running along line 2-2
in figure 1.
In its basic structure the eye 12 consists of a globe having an outer coat, a
middle layer
and an inner layer. The outer coat is made up of a tough fibrous, white layer -
the sclera 16,
which communicates with the conjunctiva 18 which is a mucous membrane that
lines the inner
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surfaces of the eyelids and folds back to cover the front surface of the
eyeball, except for the
central clear portion of the outer eye which is the cornea 20. The middle
layer contains
pigment and forms the iris 22. The inner layer is the light seeing layer or
retina 24. The lens 26
is an oval disc which sits behind the iris 22. It is conventional belief that
the cornea 20 focuses
approximately two-thirds of the light entering the eye 12 and the lens 26
about one third. Lens
accommodation or focusing is by simple explanation accomplished by the ciliary
muscle 28
pulling upon zonules 30 communicating between the ciliary muscle 28 and the
lens 26.
As people age, many suffer from Presbyopia which is a vision condition in
which the
lens 26 loses some of its flexibility, or the zonules 30 become elongated
making it harder for the
ciliary muscle 28 to focus the lens 26 as needed. Through implanting the
device 10 using the
surgical method herein disclosed, it is thought that the rejoined sclera 16
tends to pull over the
device 10 and impart resulting tension to the ciliary muscle 28 giving it more
working distance
or travel and resulting ability to pull upon the lens 26 for better
accommodation as patients
receiving the device using the method of implantation have had improved vision
thereafter. It is
also thought that a decrease in the lens 26 equatorial diameter and a slight
stretching of the
zonules 30 increasing their working range also results from the scleral
tension developed by the
rejoining of the sclera 16 over the inserted device 10, all combine to
increase amplitude of
accommodation following the implantation surgery.
Intraocular pressure in the eye 12 is caused by a build up of fluid in the
anterior chamber
36 and posterior chamber 38 when that fluid which is naturally produced in the
eye 12, fails to
be communicated through the trabecular meshwork (similar to the grate on a
manhole) into the
Canal of Schlemm which is the sewer system duct of the eye getting rid of
excess fluid and the
waste products of the eye. It has been found that following the procedure
using the
aforementioned method of implantation of the device 10 in the eye of patients,
that the drainage
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of aqueous fluid from the eye increases resulting in a drop of intraocular
pressure. As best can
be understood, the apparent tightening of the sclera 16 after implantation of
the device in the
four quadrants of the eye 12, apparently has a tightening or tensioning effect
on the ciliary
muscle 28 and its connection to the lens 26 and concurrently helps to improve
the flow of fluid
through the trabecular meshwork in the same region to aid in evacuation of
fluid from the
anterior chamber 36 and posterior chamber 38. Of course other explanations may
be apparent to
those skilled in the art and such are anticipated however in the current best
mode patients do
experience a drop in fluid pressure in the eye subsequent to the implantation
of the device 10
using the method herein disclosed.
In exercising the surgical method for insertion of the implant device 10 the
surgeon
would begin with a small limited conjunctiva) peritomy as shown by the
conjunctiva) incisions
32 of figure 1. In the current best mode of the method a plurality of
conjunctiva) incisions 32 are
performed with four being the current best number, with one in each quadrant
of the eye 12
located in-between the muscles 48 attached to the exterior of the eye 12. The
conjunctiva)
incisions 32 expose the sclera 16 wherein next, in each conjunctiva) incision
32, a radial incision
34 is made radially or generally inline with the axis 14 of the eye 12 running
through the center
of the iris 22 and out the back of the eye 12. The radial incisions 34 it has
been found, are best
made posteriorly .S mm from the limbus and measuring substantially 3 mm in
length and
approximately 600 microns in depth. However it does depend upon the dimensions
of the device
implanted and the size of the radial incisions may change to accommodate
differently
dimensioned devices 10. Such an substantial inline orientation of the radial
incisions 34 to the
axis 14 or radial to the circle forming the iris 22, has been found to produce
the best results for
both accommodation and increased drainage of the eye 12.
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Once the radial incisions 34 are complete and correctly axially oriented and
positioned in
the aforementioned manner, an implant device 10 is positioned within the space
formed by the
radial incision 34. At this point the radial incision 34 may be closed using a
means of closure
such as a suture 44 which pulls the scleral flap 21 over the implant device 10
when so rejoined
exerting tension upon the sclera 16 and to communicating structures of the
sclera 16. Those
skilled in the art will recognize that other means of closure of such
incisions are available and
new means are continually being discovered and the use of such is anticipated.
A radial cavity
19 is formed when the scleral flap 21 is rejoined to the sclera which
surrounds the implant
device 10 was placed in the radial incision. It is also anticipated that the
implantation of the
implant device 10 radially oriented away from the cornea 20 might be done in
other fashions
such as drilling or injection or in the future, with a laser or means of
mechanization, and such is
anticipated. The important aspect of the device and method herein described is
that the implant
device 10 is placed radially oriented and surrounded by the sclera in a formed
cavity and the
current best mode of achieving a radial cavity 19 to hold the implant device
10 radially oriented
respective to the cornea 20 is by the surgical method herein described.
Following closure of the radial incisions 34, the conjunctival incisions 32
are closed
using cautery or other means of such closure. The method now being complete,
the implant
device 10 is properly placed to improve both the vision and fluid drainage of
the patient. The
implant device 10 may be removed in the reverse order.
The implant device 10 used in combination with the surgical method, in the
current best
mode, is formed of a material that is inert when in contact with body tissue.
The implant device
as noted, occupies the radial cavity 19 formed when the radial incision 34 is
closed in the
aforementioned method. A tightening or tensioning of the sclera 16 layer is
provided when the
radial incision 34 is closed and the scleral flap 21 is sutured or otherwise
rejoined with the sclera
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16 and stretched over the implant device 10 during closure. Favored materials
include one or a
combination of materials from a group including hydroxiapartite, silicone,
polymethylmethacrylate, acrylic, and tantalum. Those skilled in the art will
recognize that other
materials could be used and new materials are continually being developed for
implants and the
use of such is anticipated.
The implant device 10 has body portion 46 and a means to anchor the device in
radial
cavity 19 to substantially prevent movement, which in a current preferred
embodiment is
provided by anchors 48 protruding from the body portion 46. Other means to
anchor the device
when placed in the radial cavity could accomplished be through the use of a
serrated surface 50,
or curved projections 52, or detents 54 in the exterior surface of the body 46
or apertures 56
which would communicate through the body 46. Or, one or combinations of such
means to
prevent movement of the implant device 10 can be used together.
Optionally, should the delivery of drugs to the point of implantation be
desirable, which
with many illnesses such localized delivery is, the device 10 can be provided
with a means to
communicate drugs from a device resident supply of drugs, to the device to the
surrounding eye
tissue. This drug delivery system can be provided by one or a combination of
micro
encapsulated drug coatings or other polymer or prolonged dissolving coatings
58 on the exterior
of the device, or through a reservoir 60 inside the body 46 which would hold a
supply of the
drug of choice in either solid or liquid form and communicate the drugs
through channels 62 to
the surrounding tissue. Or the material from which the device 10 is produced
can be
impregnated with the appropriate drug and secrete the same over time. When a
reservoir 60 is
used, the dosage and delivery time can be modulated by adjusting the amount of
communication
achieved through the channels 62 or just as the coating can, by adjusting the
polymer or other
substance in which the drug is dissolved to yield dissolution that will
deliver the dose for amount
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of time desired for infusion. From the reservoir 60 the device would secrete
the drugs over a
determined period at the determined dose and then can be refilled through a
channel 62 by a
hypodermic needle 27 which would pierce the sclera 16 and refill the reservoir
60 through one of
the channels 62 or a similar passage designed for such a refill. Refill can
thus be accomplished
without the need for the implant device 10 to be removed or disturbed from its
secure mount
inside the radial cavity 19.
Figure 6 depicts the device 10 with a body 46 that is round or barrel shaped
rather than
the cube or rectangular shape of figures 3-5. The body 46 would work well in
either
configuration so long as one of the noted anchoring means projects from it to
anchor the device
in the radial cavity. While the curved projections 52 are shown on all sides,
it may be
beneficial in some cases to omit them from one side for smooth transition of
the scleral flap 21
over the implant device 10.
While all of the fundamental characteristics and features of the present
invention have
been described herein, with reference to particular embodiments thereof, a
latitude of
modification, various changes and substitutions are intended in the foregoing
disclosure and it
will be apparent that in some instance, some features of the invention will be
employed without
a corresponding use of other features without departing from the scope of the
invention as set
forth. It should be understood that such substitutions, modifications, and
variations may be
made by those skilled in the art without departing from the spirit or scope of
the invention.
Consequently, all such modifications and variations are included within the
scope of the
invention as defined by the following claims.
What is claimed is:
