Surgery – Miscellaneous – Methods
Reexamination Certificate
2001-04-10
2004-06-08
McDermott, Corrine (Department: 3738)
Surgery
Miscellaneous
Methods
C604S521000
Reexamination Certificate
active
06745776
ABSTRACT:
BACKGROUND OF THE INVENTION
Hyaluronic acid is a natural, high molecular weight, highly viscous polymer consisting of alternating acetylglycosamine and glucuronic acid units. This acid is found in the trabecular meshwork in the vitreous humor of the eye, as well as in other locations in the body. The polymeric structure of hyaluronic acid is broken down by the enzyme hyaluronidase which cleaves the glycosidic bonds.
Hyaluronic acid, a mucopolysaccharide, has been used in eye surgery for over twenty years. High molecular weight hyaluronic acid is used primarily as a spacer during cataract and intraocular lens surgical procedures. It is also used in other ocular surgical procedures such as glaucoma, vitreous and retina surgery and in corneal transplantation. Hyaluronic acid solutions are pseudoplastic and the cellular protective qualities of hyaluronic acid are primarily related to the fact that it keeps tissue apart and therefore prevents contact trauma.
A common side effect occurring in postoperative cataract patients is a significant early, and occasionally prolonged, rise in intraocular pressure. Such a condition is sometimes serious, especially in patients with glaucomatous optic disc changes. Although the pressure increase tends to be more severe when visco-elastic agents such as hyaluronic acid are injected into the eye during surgery, the intraocular pressure can become elevated postoperatively even when such agents are not utilized. Furthermore, such a pressure increase can occur even when no additional medications are used during the surgical procedure. In some cases, it is advantageous to leave a viscoelastic agent in the eye, which often necessitates giving patients large doses of carbonic anhydrase inhibitors. These inhibitors lower the intraocular pressure by decreasing the formation of aqueous humor, a fluid that is normally secreted in the eye, by the ciliary body. Current methods for relieving postoperative pressure increases in the eye include various types of eyedrops such as beta-adrenergic blocking agents, sympathomimetic agents, miotics, alpha II selective agents, carbonic anhydrase inhibitors and prostaglandin agents. Tables listing some of these agents appeared in the
Physician's Desk Reference for Ophthalmology
2000.
Such methods for relieving the intraocular pressure are often undesirable because of the side effects of many of these drugs. For example, carbonic anhydrase inhibitors can cause lethargy and, in some instances, disorientation. Beta-blocker medications are contraindicated in patients with breathing problems or slow heart rates. Sympathomimetic drugs can cause an increase in blood pressure. Parasympathomimetic drugs can be associated with retinal detachments in eyes with peripheral retinal and retinovascular diseases. The above medications all work to lower intraocular pressure by either decreasing aqueous humor formation or increasing the amount of aqueous humor outflow (removal) from the anterior chamber. In some instances, if significant amounts of hyaluronic acid or a similar product are left in the eye and medications are not effective in lowering the intraocular pressure, it may be necessary to surgically aspirate them. However, aspirating the remaining hyaluronic acid from a patient's anterior chamber subjects the patient to an additional operative procedure.
There remains a need in the art to improve eye surgery by reducing postoperative intraocular over-pressure without side effects, while maintaining the effectiveness of the visco-elastic agent, such as hyaluronic acid, during the course of the operation.
BRIEF SUMMARY OF THE INVENTION
According to the present invention, a method for reducing postoperative pressure in an eye comprises anesthetizing the eye, administering to the eye substantially concurrently amounts of hyaluronic acid and hyaluronidase, performing an operative procedure on the eye, and leaving all or some of the hyaluronic acid and hyaluronidase in the eye after the procedure. The hyaluronidase is administered in an amount effective to reduce the intraocular pressure to substantially pre-operative levels by breaking down the hyaluronic acid without decreasing its effectiveness during surgery nor causing side effects in the patient.
DETAILED DESCRIPTION OF THE INVENTION
According to the present invention, a method is provided for reducing the intraocular pressure buildup which often occurs following eye surgery, especially anterior segment surgery, such as cataract and corneal transplant surgery and, in some instances, glaucoma surgery. A preferred embodiment of this invention comprises anesthetizing the eye, administering to the eye substantially concurrently amounts of hyaluronic acid and hyaluronidase, performing an operative procedure on the eye, and leaving some or all of the hyaluronic acid and hyaluronidase combination in the eye after the procedure. As will be described further below, both hyaluronic acid and hyaluronidase are administered to the eye rather than administering only hyaluronic acid. In one embodiment of this invention, the hyaluronic acid and the hyaluronidase may be mixed prior to administration. It is preferred if they are mixed no longer than up to about 30 minutes prior to administration, and more preferred if they are mixed no longer than about 5 minutes to about 10 minutes prior to administration.
In a preferred embodiment, the hyaluronic acid and the hyaluronidase may be mixed substantially contemporaneously with the administration. One way to administer the two components in such a way is via a double-barreled syringe or other mixing syringe, such that mixing occurs in predetermined concentrations in the syringe or in the needle immediately prior to or during injection. Such a method eliminates the need to measure the two components, mix them, and subsequently inject the mixture.
Syringes and devices designed for the simultaneous injection of different fluids are known in the art. For example, there are syringes in which different components are loaded into separate chambers and which can be injected separately or mixed upon injection (U.S. Pat. No. 5,599,312 of Higashikawa). In some syringes of this type, the barrel is used as a mixing chamber for multiple components which are then dispensed through the needle as a mixture (U.S. Pat. No. 5,643,206 of Fischer). It is also possible to load multiple syringes, each containing a single component, into a specially designed dispenser which is configured to inject the contents of the syringes simultaneously through a needle (U.S. Pat. No. 5,876,380 of Manganini, et al.). Other useable syringes and devices will be evident to those skilled in the art.
A preferred method of administering the hyaluronic acid and hyaluronidase is by injection during anterior segment or posterior segment surgical procedures, although other methods of administration known in the art are possible as well. It is preferred if the hyaluronic acid and the hyaluronidase are administered by injection into the anterior chamber during anterior segment ocular surgical procedures to allow the hyaluronic acid to act as a spacer during the start of the surgical procedure. In some cases of corneal transplantation, the hyaluronic acid and hyaluronidase combination may be placed on the surface of the intraocular structures prior to suturing the corneal transplant in place. This combination may also be used in posterior segment surgery, such as retina or vitreous surgery.
Hyaluronic acid is a natural, high molecular weight, viscous polymer consisting of alternating &bgr; 1-3 glucuronic and &bgr; 1-4 glucosaminidic bonds (See
The Merck Index
, monograph 4675, pages 751-752, 11
th
Ed., 1989). A preferred form of hyaluronic acid is Healon™, commercially available from Pharmacia and Upjohn Labs, Inc. Healon™ is a high molecular weight fraction of sodium hyaluronate, a polysaccharide made up of disaccharide units linked by glycosidic bonds, in a physiological buffer. The average molecular weight of sodium hyaluronate is 4 million daltons (ranging between 2 and 5 million). H
Akin Gump Strauss Hauer & Feld L.L.P.
Barrett Thomas C.
McDermott Corrine
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