Prosthesis (i.e. – artificial body members) – parts thereof – or ai – Eye prosthesis – Intraocular lens
Reexamination Certificate
2000-05-10
2003-02-11
Isabella, David J. (Department: 3738)
Prosthesis (i.e., artificial body members), parts thereof, or ai
Eye prosthesis
Intraocular lens
C623S006520, C623S006460
Reexamination Certificate
active
06517577
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates the field of ophthalmology, and particularly to crossed haptics for intraocular lenses (“IOL”), the intraocular lenses comprising the haptics are suitable for implantation of an appropriate optic in either a phakic or an aphakic eye. One suitable optic is a thin lens where the optic is rolled into a circle or oval and the haptics are placed inside the optic when rolled.
2. Anatomy of the Eye
The human eye functions much like a camera. It accommodates to changing lighting conditions and focuses light rays originating from various distances from the eye. When all of the components of the eye function properly, light is converted to impulses and conveyed to the brain where an image is perceived. See Northwest Kansas Eye Clinic website Dec. 6, 1999, “How The Eye Works,” Glaucoma, Ocular Anatomy and Function.
Light rays enter the eye through a transparent layer of tissue known as the cornea. The surface that a contact lens rests upon is the outer surface of the cornea. The outer surface is also known as the epithelium layer of the cornea. The inner surface of the cornea is the endothelium. As the eye's main focusing element, the cornea takes widely diverging rays of light and bends them through the pupil, the dark, round opening in the center of the colored iris. With the condition Myopia or nearsightedness, if the eye is too long, or the cornea has too much focusing power, images focus in front of the retina. The light rays have passed the correct focal point by the time they reach the retina. The retina then sends an “over-focused,” blurry image to the brain. Hyperopia, or farsightedness, is the opposite of myopia; images focus on a point beyond the retina. This condition is a result of an eye that is too short or a cornea that lacks the necessary refractive power to focus images on the retina. Note the main focusing element of light rays entering the eye is the cornea. Light rays then pass through the anterior chamber of the eye, which is the area between the inside of the cornea and the iris.
The lens of the eye is located immediately behind the iris and pupil. The purpose of the lens is to make the delicate adjustments in the path of the light rays in order to bring the light rays into focus upon the retina, the membrane containing photoreceptor nerve cells that lines the inside back wall of the eye. The photoreceptor nerve cells of the retina change the light rays into electrical impulse and send them through the optic nerve to the brain where an image is perceived.
For the purpose of the present disclosure, common definitions known to one of ordinary skill in the art are used for common parts of the eye. For example, the cornea is understood as being the transparent, outer “window” and primary focusing element of the eye. The outer layer of the cornea is known as epithelium. Its main job is to protect the eye. The epithelium is made up of transparent cells that have the ability to regenerate quickly. The inner layer of the cornea, endothelium, is also made up of transparent tissue, which allows light to pass; however, the endothelium does not regenerate when damaged.
The pupil is the dark opening in the center of the colored iris that controls how much light enters the eye. The colored iris functions like the iris of a camera, opening and closing, to control the amount of light entering through the pupil.
The lens is the part of the eye immediately behind the iris that performs delicate focusing of light rays upon the retina. In persons under 40, the lens is soft and pliable, allowing for fine focusing from a wide variety of distances. For individuals over 40, the lens begins to become less pliable, making focusing upon objects near to the eye more difficult. This is known as presbyopia.
The retina is the membrane lining the back of the eye that contains photoreceptor cells. These photoreceptor nerve cells react to the presence and intensity of light by sending an impulse to the brain via the optic nerve. In the brain, the multitude of nerve impulses received from the photoreceptor cells in the retina is assimilated into an image.
Finally, the anterior chamber is the small space between the cornea, endothelium, and the iris. The pupil is the central hole in the iris. The natural lens of the eye is located immediately behind the iris. The anterior chamber is filled with a clear fluid that carries oxygen and nutrients to the cornea and lens. Metabolic waste products produced by the lens and cornea are also removed by this fluid. An organ called the ciliary body located behind the iris constantly produces fresh fluid called aqueous. The fluid then circulates from behind the iris through the pupil, moves through the anterior chamber and finally exits through a drainage mechanism called Schlemm's Canal. See
FIG. 1
, a photograph of a slide, with the arrow pointing to Schlemm's Canal.
The entrance to the canal is a filtering network called the trabecular meshwork. The fluid produced by the ciliary body meets some resistance when exiting the anterior chamber through the trabecular meshwork causing pressure to build up inside the eye. The balance between the amount of aqueous production and the ease of drainage through the trabecular meshwork is very important. If the aqueous is produced at higher rate than the rate of drainage, the pressure inside the eye will rise. If it rises high enough, damage to the optic nerve will occur with associated loss of visual function. The condition of unbalanced pressure in the eye is called glaucoma. Uncorrected glaucoma can lead to permanent blindness.
2. Description of the Prior Art
Ophthalmologists have been developing the art of implanting an artificial lens in the human eye for many years, both to replace the natural lens which has been removed due to disease (an aphakic eye), and to supplement the natural lens with a corrective lens (a phakic eye).
Various pathologic disease processes can cause deterioration of the natural lens requiring removal of the lens, most notably the opacification of the lens which occurs in cataracts. In the developmental stage, cataracts may be treated by frequent changes of eyeglass prescription. When useful vision is lost, the natural lens is generally removed, either intact or by emulsification. When the lens has been removed, correction is achieved either through spectacles, contact lenses, or an intraocular implant.
Over fifty years ago, an ophthalmologist implanted the first lens after the removal of the natural lens due to cataracts (aphakic eye). The early lenses were placed in the anterior chamber of the human eye. From the initial implants, surgeons wanted a lens where radically one size would fit all eyes. The initial lenses were constructed from one piece of material where the optic and haptic footplates were part of a solid piece of material. A typical lens from the late 1970's is shown in FIG.
2
.
By the early 1980's, technology was developed to where the haptic foot plates and the optic could be connected from one piece of material using stems approximately 200 microns in diameter. For anterior chamber aphakic implants the lens are still very popular in 1999; however, over 97 percent of all cataract operations are done by placing a lens in the posterior chamber of the eye. Most surgeons begin using posterior chamber lens because anterior chamber lens required radial sizing to fit the eye and blocked the aqueous flow through a portion of the trabecular meshwork. If the sizing was not perfect, additional pressure was placed on the trabecular meshwork, which projected additional pressure on Schlemm's Canal, this further restricted aqueous flow. Blocking aqueous flow increases the internal pressure of the eye (i.e., glaucoma). An additional problem with the anterior chamber lens is the footplates are approximately 250 microns thick, which restricts the portion of the trabecular meshwork where the footplate is contacting the tissue. After most of the profession changed to posterior chamber l
Callahan J. Scott
Callahan Wayne B.
Chattopadhyay Urmi
Isabella David J.
Schelling Douglas W.
ThinOptx, Inc.
Waddey & Patterson PC
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