Title:  Method of regulating pressure with an intraocular implant

United States Patent:  6,468,283

Issued:  October 22, 2002

Inventors:  Richter; Jacob (Ramat Hasharon, IL); Pinchasik; Gregory (Ramat Hasharon, IL); Yaron; Ira (Har Adar, IL)

Assignee:  Optonol, Ltd. (Neve Ilan, IL)

Appl. No.:  383472

Filed:  August 26, 1999

An ophthalmic implant for treatment of glaucoma, a delivery device for implanting such an implant, and a method of implanting such an implant. The implant includes a tube having an inlet end, an outlet end, and a tube passage therebetween, and a disk connected to the tube at the outlet end of the tube. The tube passage has a cross-sectional area sufficiently small to inhibit the flow of aqueous humor through the tube passage. The implant provides a bleb of aqueous humor under the conjunctiva so that the bleb and the elasticity of the conjunctiva assist in regulating the flow of aqueous humor through the tube as a function of the IOP. The tube at its inlet end has a beveled surface facing away from the iris and one or more circumferential holes. One or more retention projections are provided for anchoring and may be extended outwardly when the implant is implanted in the eyeball. The disk has an outer rim and one or more inner uprights. The implant is implanted by use of a delivery device comprising a handle and a rodlike instrument, with a tip for insertion into the tube passage of the implant and a retention mechanism for retaining the implant. During implantation, the implant is inserted through a slit in a portion of the conjunctiva which normally lies at a distance away from the intended implantation site.

SUMMARY OF THE INVENTION

It is an object of the invention to provide an improved ophthalmic implant which may be implanted into the eyeball for the treatment of glaucoma, a delivery device for implanting such an implant, and an improved method of implanting such an implant into the eyeball.

In one embodiment of an improved implant in accordance with the invention, an intraocular implant is provided to be implanted in the eyeball. The implant includes a tube having an inlet end, an outlet end, and a tube passage therebetween for permitting aqueous humor to flow out of the eyeball, and a disk connected to the tube at the outlet end of the tube. The tube passage may have a cross-sectional area sufficiently small to inhibit the flow of aqueous humor through the tube passage. The cross-sectional area may be sufficiently small to prevent flow when the IOP is below a threshold amount.

The disk, which is designed to be located underneath the conjunctiva, may have an outer rim for forming a reservoir having an enlarged cross-sectional area relative to the cross-sectional area of the tube passage. When aqueous humor flows through the tube passage, a bleb of aqueous humor forms under the conjunctiva so that the bleb and the elasticity of the conjunctiva assist in regulating the flow of aqueous humor through the tube as a function of the IOP.

To prevent clogging of the implant, the tube at its inlet end may be provided with a beveled surface which faces away from the iris when the implant is inserted. Additionally, one or more circumferential holes may be provided along the tube for allowing aqueous humor to flow into the tube passage even if the axial inlet opening is blocked.

To prevent clogging at the outlet end, the disk may have an outer rim as described above which raises the conjunctiva away from the axial outlet of the tube passage to allow outflow. One or more inner uprights (which may be in the form of an inner rim) may also be provided on the disk for this purpose. Clogging is further avoided by implanting the implant under the conjunctiva at a distance away from an insertion slit in the conjunctiva, such that healing of the slit does not cause scar tissue to form in the area of the axial outlet opening of the implant.

Implantation may be facilitated by further features of the implant. For example, the implant may have one or more retention projections (for example, in the form of a spur, flange, or plate). The retention projection may be rigid, or it may be made of an elastic material such that it is able to be flexed inward against the tube during penetration through the sclera. Alternatively, the retention projection may be designed to lie initially relatively flat against the tube for easier penetration through the sclera and to prevent tearing of the sclera, with a mechanism for extending the retention projection outwardly when the implant is implanted in the eyeball. For example, the retention projection may be extended outwardly by a separate expansion tool or may be constructed of a shape memory material, such as PMMA of nitinol, so that it is extended outwardly when subjected to the heat of the eyeball. One or more retention projections according to the invention are sufficient to reliably anchor the implant in the eyeball without the need for sutures, saving time and costs.

Implantation may also be facilitated by the provision of one or more markers on the implant visible through the cornea upon passing through the sclera. For example, a circumferential hole as described above may serve as a marker; alternatively, the marker may be some other suitable visible mechanism, such as a scratch or colored mark on the tube. The visibility of the marker lets the doctor know that the marker has passed through the sclera, indicating that the implant is in place.

Implantation of an implant may be performed by use of a delivery device in accordance with the invention, comprising a handle and a rodlike instrument, for example a needle or probe, for carrying the implant for insertion into the eyeball. The delivery device has a tip for insertion into the tube passage of the implant and a suitable retention mechanism for preventing the implant from moving up the delivery device during implantation. The retention mechanism may also be constructed to prevent the implant from rotating during implantation to insure proper orientation of the implant in the eyeball. The delivery device may additionally have a suitable expansion tool for extending one or more retention projections of the implant outwardly once the projection or projections have penetrated through the sclera.

In one embodiment of an improved method of implanting an implant according to the invention, a small slit is cut in a portion of the conjunctiva which normally lies at a distance away from the intended implantation site. As the implant itself is very small, the slit also may be very small, for example about 2 mm in length or less. The small size of the slit as well as its positioning at a distance away from the implantation site, for example about 10 mm, helps prevent contamination of the sclerostomy site and reduces the risk of infection.

The implant is placed through the slit, directed to the implantation site, and inserted into the sclera at the implantation site. The sclera may be pierced either by a needle-like tip of the tube of the implant formed by a beveled surface at the inlet end of the tube as described above or by the tip of a needle of the delivery device which carries the implant. Thus, the implant may be inserted directly into the eyeball without the need for any separate piercing step, resulting in cost and time savings.

An intraocular implant, delivery device, and method of implantation according to the invention provide the advantages of a full thickness fistula, while avoiding the limitations of the standard trabeculectomy. An implant according to the invention may be very small and implantable without surgery. No surgery room or hospitalization is necessary, thereby reducing costs. Implantation is minimally invasive, simple and quick, requiring only local anesthesia. Retrobulbar anaesthesia is not necessary, and thus iatrogenic damage to the optic nerve is avoided. There is no need to perform an iridectomy, and thus aqueous flow is maintained, lens nourishment is unaffected, and the likelihood of cataracts developing as a result of the procedure is reduced.

Claim 1 of 19 Claims

What is claimed is:

1. A method of regulating an intraocular pressure of an eyeball comprising the steps of:

(i) providing an intraocular implant comprising:

(a) a tube for implanting into the eyeball, said tube comprising an inlet end, an outlet end, and a tube passage extending between the inlet end and the outlet end for permitting aqueous humor to flow out of the eyeball, and

(b) a subconjunctival flange connected to the tube at the outlet end of the tube for placing on a surface of the sclera under the conjunctiva;

(ii) cutting a slit in a portion of the conjunctiva of the eyeball which normally lies at a distance away from an implantation site;

(iii) placing the implant through the slit in the conjunctiva;

(iv) directing the implant between the sclera and the conjunctiva to the implantation site; and

(v) inserting the implant through the sclera at the implantation site, including implanting the tube into the sclera and placing the subconjunctival flange on a surface of the sclera under the conjunctiva.
 

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