Prosthesis (i.e. – artificial body members) – parts thereof – or ai – Eye prosthesis
Reexamination Certificate
2000-08-04
2003-01-28
Willse, David H. (Department: 3738)
Prosthesis (i.e., artificial body members), parts thereof, or ai
Eye prosthesis
C600S037000
Reexamination Certificate
active
06511508
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention (Technical Field)
The invention relates to surgical correction of human eye refractive errors such as presbyopia, hyperopia, myopia, and stigmatism. More particularly, it is related to surgical corrections of such errors with implantation of a prosthesis for increasing or decreasing the eye length and scleral curvatures, and thus bringing the retina/macula region to coincide with the focal point of the eye.
2. Background Art
There are many refractive errors associated with the human eye. When the focal point of images is formed in front of the retina/macula region due to too much refraction of light rays, the refractive error is called myopia or near-sightedness. When, on the other hand, the focal point of images lie outside the eye behind the retina/macula region due to too little refraction of light rays, the refractive error is called either hyperopia or far-sightedness or presbyopia. These problems can be surgically corrected by either changing the eye length or scleral curvatures. In case of presbyopia, as individuals age, the human eye loses its ability to focus on nearby objects. This condition, known as presbyopia, is due to a progressive loss in the elasticity of the lens of the eye, such that the ciliary muscles which normally force the lens, through the action of zonule fibers on the lens capsule, in a rounded shape to accommodate near objects can no longer exert the necessary changes in the lens' shape.
The conventional optometric solution to the problems of myopia, hyperopia, and presbyopia is a prescription of glasses or reading glasses or, for individuals who already require glasses to correct other refractive errors such as myopia or astigmatism, a prescription of bifocal or multifocal glasses.
This century has witnessed a revolution in the surgical treatment of ophthalmic disorders and refractive errors of the human eye. This revolution ranges from corneal implantations, cataract extraction, phacoemulsification of the lens, intraocular lens implantation, glaucoma implants to control the intraocular pressure, radial keratotomy, excimer laser ablation of the cornea, trabeculoplasty, iridotomy, virectomy, and the surgical buckle treatment of retinal detachment. The recent surgical solutions to myopia, hyperopia, and stigmatism have been laser photorefractive keratectomy (PRK), Lasik (laser-assisted in-situ keratomileusis) and RK or radial keratotomy. Modern techniques proposed to correct human eye refractive errors have been corneal implants (Intacs, Keravision rings, Silvestrini, intrastromal corneal ring (ICR) ) and scleral implants (SASI, Presbycorp implants, Schachar Accommodative Scleral Implants).
The effective focal length of the human eye must be adjusted to keep the image of the object focused as sharply as possible on the retina. This change in effective focal length is known as accommodation and is accomplished in the eye by varying the shape of the crystalline lens. This is necessary for the human eye to have clear vision of objects at different distances. Generally speaking, in the unaccommodated normal vision, the curvature of the lens is such that distant objects are sharply imaged on the retina. In the unaccommodated eye, close objects are not sharply focused on the retina and their images lie behind the retinal surface. In order to visualize a near object clearly, the curvature of the crystalline lens is increased, thereby increasing its refractive power and causing the image of the near object to fall on the retina. The change in shape of the crystalline lens is accomplished by the action of ciliary muscle by which the radial tension in the lens is reduced, according to classical Helmholtz theory of accommodation, and it becomes more convex. Based on Helmholtz theory, in the unaccommodated human eye the lens and its capsule are suspended on the optical axis behind the pupil by a circular assembly of many radially directed collagenous fibers, the zonules, which are attached at their inner ends to the lens capsule and at their outer ends to the ciliary body, a muscular constricting ring of tissue located just within the outer supporting structure of the eye, the sclera. The ciliary muscle is relaxed in the unaccommodated eye and therefore assumes its largest diameter. According to the Helmholtz classical theory of accommodation, the relatively large diameter of the ciliary body in this unaccommodated condition, causes a tension on the zonules which in turn pull radially outward on the lens capsule, making it less convex. In this state, the refractive power of the lens is relatively low and the eye is focused for clear vision of distant objects. When the eye is intended to be focused on a near object, the muscles of the ciliary body contract. This contraction causes the ciliary body to move forward and inward, thereby relaxing the outward pull of the zonules on the equator of the lens capsule and reducing the zonular tension on the lens. This allows the elastic capsule of the lens to contract causing an increase in the sphericity of the lens, resulting in an increase in the optical refraction power of the lens. Recently, Schachar (whose inventions are discussed below) has proposed a radically different theory of accommodation which refutes the Helmholtz theory.
Accordingly, the present invention relates to systems and methods of compensating presbyopia, hyperopia, myopia, and stigmatism by actively changing the length of the eye globe in the direction of optical axis or its curvature, on demand, using active constricting (sphinctering) artificial muscles as active scleral bands. The scleral band in the form of an active and smart constricting/expanding band comprising an active prosthesis which can be remotely powered by small inductive generators that can be placed near the eye, preferably behind the ears or under the skin on the shoulder or on an arm band.
There are several prior art devices and methods in the form of implants and prostheses for the surgical correction of presbyopia, hyperopia, and myopia.
U.S. Pat. No. 5,354,331 to Schachar, discloses how presbyopia and hyperopia are treated by a method that increases the amplitude of accommodation by increasing the effective working distance of the ciliary muscle in the presbyopic eye. This is accomplished by expanding the sclera in the region of the ciliary body. A relatively rigid band having a diameter slightly greater than that of the sclera in that region is sutured to the sclera in the region of the ciliary body. The scleral expansion band comprises anterior and posterior rims and a web extending between the rims, the anterior rim having a smaller diameter than the posterior rim.
In U.S. Pat. No. 5,465,737 to Schachar, the teachings are similar to those of the '331 patent, except that by weakening the sclera overlying the ciliary body, by surgical procedures or treatment with enzymes, heat or radiation, whereby intraocular pressure expands the weakened sclera, or by surgical alloplasty. The effective working distance of the ciliary muscle can also be increased by shortening the zonules by application of heat or radiation, by repositioning one or both insertions of the ciliary muscle or by shortening the ciliary muscle. Presbyopia is also arrested according to the invention by inhibiting the continued growth of the crystalline lens by application of heat, radiation or antimitotic drugs to the epithelium of the lens. Primary open angle glaucoma and/or ocular hypertension can be prevented and/or treated by increasing the effective working range of the ciliary muscle according to the invention.
U.S. Pat. Nos. 5,489,299; 5,722,952; 5,503,165; and 5,529,076 to Schachar contain essentially the same ideas as U.S. Pat. Nos. 5,354,331 and 5,465,737 with some improvements such that presbyopia and hyperopia are treated by a method that increases the amplitude of accommodation by increasing the effective working distance of the ciliary muscle in the presbyopic eye. The effective working distance of the ciliary muscle is increased by shor
Shahinpoor Mohsen
Shahinpoor Parsa
Soltanpour David
Armijo Dennis F.
Environmental Robots, Inc.
Willse David H.
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