Surgical Implant Device

Abstract

Disclosed implant device includes a valve and conduit means for controlling the intra-occular pressure build up in a diseased eye.

Description

This invention relates generally to surgical devices and more particularly to a surgical device to be implanted in an eye for controlling intra-occular pressure, as, for example, in a glaucoma diseased eye wherein there is an increased pressure built up within the eye from the accumulation of fluid.

Normally, fluid called aqueous humor, which constantly forms and enters portions of the eye globe known as the anterior and posterior chambers, are balanced by those fluids which leave the eye by drainage through the canal of Schlemm. In glaucoma, for example, more fluid is secreted than is discharged, which results in an increase in intra-occular pressure, causing pain, interference with vision, and eventual blindness. In acute and chronic cases of glaucoma, this fluid imbalance is usually due to a blockage of the canal of Schlemm from a change in the character of the filtering or drainage tissues or a collapse of the angle of the anterior chamber.

Many surgical procedures for treating acute and chronic glaucoma and involving incisions and device implants have been proposed or tried, all of which has met with rather varied and inconsistent results. One such device includes, for example, an elongated tubular section curved to the same radius as an eye and an attached right angled section including a bore and adapted for insertion into a hole surgically drilled in an eye so as to provide for the drainage of fluid through the device into the retrobulbar space behind the eye.

Particular problems and disadvantages apparent in this and other prior art devices are the general lack of any provisions in the devices to safeguard against excessive drainage of fluid which could bring about a collapse of the anterior chamber causing a possible loss of sight or the eye itself. The drilling of a hole, for example, for receiving the right angled section for the above-described device may in itself cause an excessive loss of fluid. Also, devices of the type including an extended bore or continuous open channel for fluid drainage also provide a means for the outside entry of harmful bacteria into the anterior chamber, with a possible resulting infection of the eye.

It is an object of the present invention to provide an implant device which is simple in construction, free of the aforementioned disadvantages and effective in controlling excessive intra-occular pressure.

It is another object of the present invention to provide a device which when surgically implanted in a glaucomatic eye operates in a manner to relieve an excessive intra-occular pressure.

It is another object of the present invention to provide a device which when implanted in a glaucoma diseased eye serves as a drain for excess fluid built up in the anterior and posterior chambers.

Briefly described, the implant device of the present invention includes an elongated shank member have a passageway axially extending therethrough and mounting a valve therein to normally provide for closure of the passageway, the valve opening in response to a predetermined pressure differential within the passageway. A flange is provided on one end of the shank member to anchor the implant device. Means are also provided on the shank member for insuring retention of the device in the eye.

The novel features which are considered to be characteristic of the invention are set forth with particularity in the appended claims. The invention itself, however, both as to its organization and method of operation as well as additional objects and advantages thereof, will best be understood from the following description when read in connection with the accompanying drawing in which:

FIG. 1 is a vertical section of a human eye showing the device of the present invention implanted therein;

FIG. 2 is a perspective view of the implant device of the invention;

FIG. 3 is a top view of the device of FIG. 2;

FIG. 4 is an enlarged front sectional view taken along the lines 4--4 of FIG. 3;

FIG. 5 is an enlarged section of the valve area shown in FIG. 4; and

FIG. 6 is a modified front sectional view of the flange and upper shank portion of the device.

Referring now to the drawing, and to FIG. 1 thereof, there is illustrated a human eyeball which includes the lens 10, posterior chamber 12, anterior chamber 14, iris 16, sclera 18, canal of Schlemm 20, cornea 22, and the conjunctiva 24 of the eye. As shown in the Figure, the device 26 of the present invention when implanted in the eye preferably extends through the cornea 22 and into the anterior chamber 14 of the eye.

With reference particularly now to FIGS. 2, 3, 4 and 5 in the drawing, a preferred embodiment of an implant device in accordance with the present invention comprises an elongated body or shank portion 28 generally cylindrical in shape, slightly tapered, and having a bore or passageway 30 extending axially therethrough. One end 32 of the shank portion 28 is capped by an integrally formed circular flange 34 with the passageway opening therethrough. The other end of the passageway opens through the bottom portion 36 of the shank 28 which has an obliquely slanted end face 38 to facilitate implantation of the device 26 into an eye as will hereinafter be described.

As shown particularly in FIG. 4, the flange portion 34 is preferably slanted or obliquely positioned relative to the longitudinal axis of the shank portion and has its top and bottom surfaces 40 and 42 arcuately contoured so as to conform generally to the cornea or other portion of the eyeball surface into which the device is to be implanted. The flange portion 34 being seated thereon thus serves to prevent the implant device from being submerged into the eye after insertion.

In spaced array along the periphery of the flange portion 34 are a plurality of apertures 44. Spaced downwardly from the flange portion 34 and extending up and outwardly from the outside surface of the shank portion 28 are a pair of integrally formed projections or barbs 46 which may serve as a means for retaining the device in the eye after implantation. It is important that the barbs 46 be spaced sufficiently beneath the underside of the flange so as to accommodate therebetween the wall thickness of the cornea or other portion of the eyeball receiving the implant device, or alternately be spaced so as to lock within the stroma or mid point of the cornea.

In accordance with the invention, a valve means 48 is provided and seated within the shank passageway 30 so as to normally provide for a closure of the passageway, and for opening in response to a predetermined pressure differential within the passageway and on opposing portions of the valve means.

More particularly, and as shown in FIG. 5, a preferred valve means includes a pair of opposing flexible web or reed-like members 50 and 52 formed integral with and extending out from the inside wall surfaces bounding the passageway 30 and normally abutting one another so as to close off the passageway and inhibit any flow therethrough. Preferably the valve is formed in the shank portion at a point intermediate the ends thereof. The abutting engagement of the reed members 50 and 52 is such that the valve functions in a one-way manner by allowing for the upward deflection of the reed members 50 and 52 in response to the presence of a predetermined increase in pressure exerted on the bottom surfaces 54 and 56 (as viewed in the Figures) of the reed members relative to the pressure exerted on the top surfaces 58 and 60 of the reed members.

It will be appreciated that in fabricating the device of the invention, the material chosen must be inert and nontoxic. Also it is desirable that the material be somewhat resilient so as to allow for an integral formation within the internal passageway of a one-way valve. One material that has proved satisfactory for this purpose is manufactured by the DuPont Company, under the trade name "Teflon". The double reed valve may be fabricated, for example, by machining the shank portion bore from both ends to provide a diaphragm like membrane between the bored end portions. The membrane is then pierced to create a double reed type valve. Piercing of the membrane is from the bottom end of the bore such that the reed valve operates to open only toward the top or flange end of the shank, thereby functioning as a one-way type valve. The valve is thus dependent on the memory retention or resiliency of the material of which it is formed, in addition to the back pressure exerted on the flange side of the valve, to return to its seat or closed position.

It should be noted that the pressure differential or program setting to which the valve openly responds is determined by the thickness of the membrane forming the reed members, the general characteristics and resiliency of the material used in fabricating the device as well as the size of the bore opening or passageway.

Advantages in the use of a double reed type valve are the relative ease with which the response threshold point of the valve can be controlled, i.e., the point at which the valve responds to a pressure difference. Also the greater the pressure difference, the more the valve flaps or reed members will deflect to open the passageway and allow for fluid discharge, the valve opening being directly proportional to the applied pressure differential.

It will be also be apparent that other types of valve means, as, for example, a ball valve, single reed valve or a spring valve may be used in the construction of the device of the present invention.

Insertion and operation of the implant device into an eye will now be described.

As shown in FIG. 1, the device of the present invention may be implanted into and through the cornea 22 and into communication with the anterior chamber 14, the implantation preferably being made in the upper portion of the cornea just beneath the canal of Schlemm 20.

As was heretofore noted, the shank portion of the implant device is preferably provided with a tapered outside contour as shown in the Figures so as to facilitate easy insertion, either directly or through a prepared tract into the eye. When insertion of the implant device is to be in the cornea, for example, a hyperdermic needle-like instrument is preferably used to first pierce the cornea to provide a tract for receiving the device. The cornea is a desirable area of the eye for receiving the device since the inherent pliable nature of the cornea will permit the easy implantation of the device and also enhance a sealing around the shank portion of the device after it is received in the eye. Also, in piercing the cornea to provide the receiving tract for the implant device, there is substantially no tissue or fluid loss.

It will be understood that the device can be inserted directly into the cornea without the aid of a tract. Also, other areas of the eyeball may be used for implantation of the device of the present invention.

Upon implantation, the device flange portion 34 will seat on the cornea or other area of the eye receiving the device, while the barb projections 46 lock against the underside of the receiving tissue for retaining the device in the eye. Alternately, the barb projections may be spaced so as to lock within the stroma of the cornea, or mid area of the receiving tissue.

As was heretofore noted, the flange portion 34 of the implant device may be provided with a plurality of apertures 44 spaced around the periphery thereof. These flange apertures 44 may serve two functions. When the device is implanted in the cornea portion of the eye, the apertures allow the eye tears to wash and provide for the normal irrigation of the cornea area under the flange. Where the implant is in another area of the eye, as, for example, through the sclera, the flange apertures may be used to anchor the device in the eye with the aid of sutures.

Initially the pressure of the top surfaces 58 and 60 of the valve, i.e., the discharge end of the valve, which is exposed to the outside of the eye after implantation of the device, is at or about the atmospheric pressure. Normally, the pressure inside the eye globe, and more particularly in the anterior and posterior chambers thereof is understood to be between 15 and 25 millimeters (mm.) of mercury above the atmospheric pressure. With the occurrence of an abnormal intra-occular build up of pressure inside the eye and again particularly in the anterior chamber which after insertion of the device is effectively in communication with the bottom surfaces 54 and 56 of the reed members, i.e., the intake end of the valve, a point is reached, i.e., the threshold or program setting of the valve, wherein the valve will open to allow the passage of fluid from the anterior chamber through the shank bore of passageway to the outside of the eye wherein it mingles with existing eye tears and is disposed of in the normal manner. The increased intra-occular pressure built up is in this way controlled. The pressure point at which the valve may be programmed to open may, for example, be between 20 and 25 mm. of mercury.

When the pressure difference on both sides of the valve membrane, i.e., the top and bottom surfaces of the reed members, decreases to a preset level substantially equal to the aforementioned program setting, the valve closes. The rate and degree of valve opening is a function of the amount of the intra-occular pressure and consequently the pressures exerted on the bottom surfaces of the valve reed members. The valve serves to regulate the flow of fluid through the shank passageway in direct proportion to the degree of excessive intra-occular pressure built up in the eye. Since the intra-occular pressure will be changing as the valve allows for the discharge of fluid, the valve reeds will tend to substantially open and close or flutter in operation. Since the cornea does not have blood vessels or a blood supply, by this fluttering action of the valve, the circulation of the aqueous is enhanced against the posterior part of the cornea. This is desirable since the aqueous normally provides a means of carrying nourishment to the cornea and also for the disposal of waste matter.

It should be noted that another advantage inherent in the implant device of the present invention is its minute size. A device in accordance with the invention has been constructed with an operating valve as above-described and with a shank length of approxiamtely 2.5 mm., a bore diameter of approximately 0.5 mm., and a flange portion 2 mm. in diameter.

It will be appreciated that the relatively small size of the device will minimize friction between an eyelid and the device when implanted. Also, during implantation of the device and because of its size, there will be substantially no tissue of fluid loss.

Turning now to FIG. 6, there is illustrated a fragmentary sectional view showing a modified embodiment of the flange and retaining means portons of the implant device of the present invention.

More particularly, the upper end of the shank portion 28 is necked down as shown so as to provide a step or shelf 62 which functions to help retain the implant device in an eye in a manner similar to that of the heretofore described barb projections shown in FIG. 4. The top surface 40 of the flange portion 34 is provided with an integrally formed annular rib or ridge member 64. With the device implanted in an area of the eye other than the cornea, and more particularly the sclera, the ridge 64 will serve to discourage the formation of cicatrix or scar tissue over the flange opening of the passageway.

It will thus be seen that the device herein described may be easily implanted in a human eye, provides a minimum of discomfort to the recipient, and functions in a simple, eyt effective manner to control an intra-occular pressure build up. It will also be clear that variations in the details of consruction which are specifically illustrated and described may be resorted to without departing from the scope of the invention.

Claims

What is claimed is:

1. A surgical implant device for implantation in an eye comprising:

an elongated shank member generally tubular in shape and having a flange surrounding one end thereof, said shank member being provided with a passageway opening in said one end through said flange and axially extending through said shank and out the other end thereof;

valve means seated within said passageway and normally positioned to provide for closure thereof, said valve means opening in response to a predetermined pressure differential within said passageway and on opposing sides of the valve; and

means integrally formed on and disposed along said shank member axially spaced from said flange for the retention of said device in an eye;

said flange being in an inclined position relative to the axis of said shank member and the side of said flange from which the shank extends being arcuately contoured to conform generally to the surface of a human eye.

2. A device as defined in claim 1 wherein said retention means includes a plurality of spaced projections formed on the outside surface of said shank member and angled upwardly toward said flange portion.

3. A device as defined in claim 1 wherein a first portion of said shank member depends from said flange portion and is necked down to form a step with the remaining portion thereof, the remaining portion of said shank member thereafter tapering toward said botton end.

4. A device as defined in claim 1 wherein said flange includes a ridge member integrally formed on the surface thereof opposite said shank and concentric with the opening therein,

5. A device as defined in claim 1 wherein said valve means includes a pair of opposing reed members integrally formed within said passageway and extending thereacross so as to normally close off said passageway.

6. A device as defined in claim 5 wherein said flange includes a plurality of openings spaced around the periphery thereof.

7. A surgical device for implantation in an eye comprising:

a flange portion having top and bottom surfaces and a central aperture therein;

an elongated body portion integral with said flange portion and depending from the bottom surface thereof, said body portion having an internal passageway continuous with said flange opening and extending lengthwise through said body portion to an axially in-line opening at the other end thereof;

pressure sensitive valve means seated within said passageway and normally positioned to provide for closure of said passageway, said valve means opening in response to a predetermined pressure differential within said passageway and on opposing sides of the valve;

said flange portion being generally circular in shape and overlying said body portion in an inclined position relative to the longitudinal axis of said body portion, said flange including a plurality of apertures spaced along the periphery thereof; and

means integrally formed on and displaced along said body portion beneath said flange portion for the retention of said device in an eye, said retention means including a plurality of spaced projections formed along the outside surface of said body portion and angled upwardly toward said flange portion.