Surgery – Means for introducing or removing material from body for... – With means for cutting – scarifying – or vibrating tissue
Reexamination Certificate
2000-02-16
2003-01-14
Jacyna, J. Casimer (Department: 3751)
Surgery
Means for introducing or removing material from body for...
With means for cutting, scarifying, or vibrating tissue
C604S107000, C604S170030, C604S180000
Reexamination Certificate
active
06506176
ABSTRACT:
FIELD OF THE INVENTION
This invention relates generally to medical methods and devices, and more particularly to methods and devices for removing the lenses from the eyes of mammalian patients.
BACKGROUND OF THE INVENTION
A. Pathological and Age Related Changes of the Ophthalmic Lens
The lens of a human eye is a crystalline, transparent biconvex structure that serves to focus rays of light on the retina of the eye. The lens consists of a central portion or “nucleus” and a peripheral portion or “cortex” and is enclosed within a lens capsule. The lens capsule is a bag-like anatomical structure that surrounds the lens and is suspended by fine ligaments that are attached to the ciliary muscles. The ciliary muscles radially stretch and relax the capsule thereby flexing the lens in a manner that varies the optical characteristics of the lens to provide the desired focus for an image. This is commonly referred to as accommodation.
The lens cortex is a jelly-like portion of the lens and is located between the denser inner nucleus and the elastic outer capsule. The lens nucleus is an optically defined-zone which is denser in the central position of the lens. The lens nucleus becomes even denser with age, and can eventually harden and fill increasing portions of the total lens space. Age-related hardening of the lens typically results in a condition known as presbyopia or farsightedness. Additionally the lens may become opacified and/or cloudy. This opacity or cloudiness of the lens is commonly referred to as a cataract.
B. The Pathogenesis and Treatment of Cataracts
Cataracts can be present at birth or can be caused by trauma, toxins, radiation, or certain diseases (e.g., diabetes mellitus). Approximately ninety percent of all cataracts form as a result of the aging of the lens, which can occur as early as age 40. Although cataracts can develop in people at any age, it is a virtual certainty that people who live long lives will eventually develop some degree of cataracts.
The cataractous lens obstructs the passage of light and tends to prevent the formation of a clear image on the retina. Once a cataract develops, it typically becomes more severe over a period of years, though some develop more rapidly. As a cataract “matures,” the initial change is a yellowing in the lens, which becomes cloudy or opacified.
There is one stage in the development of some cataracts when “near” vision actually improves while “distance” vision worsens. This condition is known as “second sight,” when some people can read without their glasses. However, the cataract will continue to progress so that even “near” vision becomes blurred.
Surgery (i.e., surgical removal of the cataractous lens) is currently the only method of restoring vision in a patient who suffers from cataracts. Generally, four types of surgical procedures are known to be useable for removing cataract-affected lenses. These four types of surgical procedures are, as follows:
Extracapsular Cataract Extraction (ECCE): An incision about 10 mm long is made in the lens capsule and the surgeon extracts the harder nucleus of the lens usually in one piece. The softer peripheral portions of the lens are then suctioned out. The typical ECCE procedure results in disruption or removal of a substantial portion of the anterior aspect of the lens capsule.
Intracapsular Cataract Extraction (ICCE): An incision about 15 mm long is made in the lens capsule and the surgeon extracts the whole lens, usually in one piece. The ICCE procedure results in disruption of the zonules so as to detach the lens with its capsule from the surrounding ciliary muscles. At least in the United States, ICCE is no longer a widely used method.
Phacoemulsification (PE): For the phacoemulsification procedure, a limbal or corneal incision of about 3 mm is made allowing insertion of the instrument's tip into the anterior chamber in a direction almost parallel to the iris. Once the incision has been made, the central part of the anterior lens capsule is typically opened widely to facilitate emulsification of the lens nucleus and cortical clean-up, as well as to provide for an ideal intraocular lens placement into the capsule.
When compared to conventional extracapsular cataract removal procedures, the phacoemulsification technique provides the advantages of a smaller incision, a stronger post-operative globe which reduces astigmatism, better wound closure, lower trauma and quicker improvement in vision. However, this phacoemulsification procedure is contraindicated, except with respect to the most highly skilled surgeon, in patients having a dislocated cataract lens, a shallow anterior chamber, miotic pupils, or low cornea-endothelial cell counts.
Inadvertent perforation of the posterior aspect of the lens capsule during the phacoemulsification procedure can result in vitreous prolapse into the lens capsule. Also, stray ultrasound energy from the phacoemulsification procedure can be destructive to the endothelial cells of the cornea, and can ultimately result in complete degeneration of the cornea.
i. Endocapsular Phacoemulsification
In a rarely performed procedure, the cataractous lens is removed by an endocapsular phacoemulsification. The cataractous lens must be carved away while not only the posterior side of the lens capsule but also most of the anterior side are left intact. A significant amount of operator skill and training is required to perform endocapsular phacoemulsification. The operator must repeatedly move the ultrasound probe back and forth, while altering its angle, to effect complete emulsification of the lens without causing trauma to or inadvertently perforating the lens capsule.
ii. Extracapsular Phacoemulsification
Extracapsular phacoemulsification can be performed in the anterior chamber or posterior chamber of the eye. In the case of anterior chamber phacoemulsification, the cataract lens is maneuvered into the anterior chamber where it is carved and removed from the chamber. Anterior chamber phacoemulsification is more traumatic to the endothelial layer of the cornea than posterior chamber phacoemulsification, but it is often an easier procedure for the surgeon to perform. Posterior chamber phacoemulsification consists of carving or shaving the central part of the lens while the lens is still in the lens capsule. This method is more difficult to perform than ECCE due to the possibility of rupturing the posterior lens capsule and exposing the vitreous which fills the volume of the posterior eyeball.
EndocapsularVortex Emulsification (EVE): The procedure is described in applicants' prior U.S. Pat. No. 5,437,678 (Sorensen), U.S. Pat. No. 5,690,641. (Sorensen et al.) and U.S. Pat. No. 5,871,492 (Sorensen). In the procedure, an EVE probe having a rotating lens-reducing head is inserted into the lens capsule through a small opening of approximately 1-3 mm that is formed in the periphery of the lens capsule. The 1-3 mm opening in the lens capsule may be formed by an electrosurgical capsulotomy device of the type described in U.S. patent application Ser. No. 08/744,404 (Mirhashemi, et al.) The EVE probe is held in a substantially stationary position while the lens-reducing head is rotated. Concurrently with the rotation of the lens-reducing head, an irrigation solution (e.g., balanced salt solution) is gently infused through the probe and excess irrigation solution and debris are aspirated out of the lens capsule causing the nucleus to rotate and thereby coming into contact with the lens reducing head. The flow causes the entire lens (including the relatively hard nucleus) to be repeatedly brought into contact with the rotating lens reducing head and fully emulsified, without the need for substantial movement or manipulation of the position of the probe. In this manner, the entire lens is removed through the small 1-3 mm opening and the anterior aspect of the lens capsule remains essentially intact.
In addition to the ECCE, PE and EVE devices and procedures described hereabove, several other devices and procedures have also been purported to be usea
Etherington Roger F.
Gerg James B.
Mirhashemi Soheila
Mittelstein Michael
Muri John I.
Bausch & Lomb Incorporated
Jacyna J. Casimer
Smith Michael L.
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