Prosthesis (i.e. – artificial body members) – parts thereof – or ai – Eye prosthesis – Corneal implant
Patent
1995-02-28
1997-07-08
Jones, Mary Beth
Prosthesis (i.e., artificial body members), parts thereof, or ai
Eye prosthesis
Corneal implant
606166, A61F 214
Patent
active
056455828
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
This invention is in the general field of medical technology and relates specifically to an intrastromal corneal ring having overlapping or connected ends for varying corneal curvature to correct vision.
BACKGROUND OF THE INVENTION
Anomalies in the shape of the eye and specifically the shape as defined in part by the corneal can cause visual disorders. Hyperopia occurs when the eyeball is too short. In such a case, parallel rays from greater than 20 feet focus behind the retina. Myopia, on the other hand occurs when the eyeball is too long. The focus of parallel rays in this case is in front of the retina. Astigmatism is a condition in which the parallel rays of light do not come to a single point, but rather have a variable focus due to the fact that the cornea is aspherical and refracts light in a different meridian at different distances. Some degree of astigmatism is normal, but where it is too high, it must be corrected in order to provide acceptable vision.
Conditions such as hyperopia, myopia and astigmatism are usually corrected by glasses or contact lenses. Surgical methods for the correction of such disorders have been cited in the literature and include radial keratotomy (see e.g. U.S. Pat. Nos. 4,815,463 and 4,688,570) and laser corneal ablation (see e.g. U.S. Pat. No. 4,941,093). Further, the general method of implanting rings in the corneal stroma to change the curvature of the cornea is known. Previous work involving the implantation of polymethylmethacrylate (PMMA) rings, allograft corneal tissue and hydrogels is well documented. One of the ring devices involves a ring design that allows a split ring to be inserted into a channel. The channel is formed by dissecting the stromal layer of the cornea using a minimally invasive incision. Thereafter, the implant is inserted into the channel and the channel is sutured shut.
U.S. Pat. No. 4,452,235, which is herein incorporated by reference in its entirety, describes a method and apparatus for corneal curvature adjustment. The method involves inserting one end of a split end adjusting ring into the cornea of the eye and moving the ring in a circular path until its ends meet. The ends are thereafter adjusted relative to each other so that the ends can be connected. When the correct size ring is inserted the eye will have been caused to assume the correct curvature.
Other devices for adjusting the corneal curvature have been disclosed such as the device shown within U.S. Pat. No. 4,671,276 issued Jun. 9, 1987. In addition, devices for affecting other parts of the eye such as an iris retaining device are disclosed within U.S. Pat. No. 4,782,820 issued Nov. 8, 1988 and a variable focus lens which is disclosed within U.S. Pat. No. 5,066,301 issued Nov. 19, 1991. More recently a method of changing cornea curvature by injecting a gel into the cornea was disclosed in U.S. Pat. No. 5,090,955 issued Feb. 25, 1992.
The present invention describes split ring devices which have end structures and configurations which provide certain advantages and improvements as compared to earlier ring structures.
SUMMARY OF THE INVENTION
The present invention is an intrastromal corneal ring (ICR) comprised of an elongated, flexible, circular body member. The ICR is of a size and shape such that it can be inserted into a human eye and specifically into the outer periphery of the cornea of a human eye. The ICR is comprised of a material which is compatible with human ocular tissue and specifically compatible with corneal tissue. The end portions of the body member may be formed in several different configurations or embodiments. The end portions overlap each other and are preferably configured such that when they are forced toward each other horizontally and/or vertically they intermesh and provide a tight fit against each other. Further, the ends are preferably configured in such a manner that when allowed to come together the resulting ring provides a smooth and continuous outer profile.
A primary object of the invention is to provide an ICR wi
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English translation of Brazilian Patent Application No. BR 8705060 (Mar. 21, 1989).
Hartmann Chr., et al., "Intrastromale Implantation Eines Justierbaren Kunstsoffringes Zur Hornhautrefraktionsanderung", Kongre.beta. der Deutschen Gesellschaft fur Intraokularlinsen Implantation, delivered by H. Freyler et al., Springer-Verlag, Wien, pp. 465-475. The corresponding English language translation of the article was authored by Hartmann, Chr., et al., entitled Intrastromal implantation of an adjustable plastic ring to alter the corneal refraction Congress for German Society for Intraocular Lens Implantation, delivered by H. Freyler et al., (7 pages total).
Simon, G., et al., "Long term in vivo topographic studies of gel injection adjustable keratoplasty (GIAK)" Abstracts: The Association for Research in Vision and Ophthalmology, Annual Meeting Abstract Issue, Sarasota, Florida, USA, May 2-May 7, 1993, p. 1248, (abstract 2679-52).
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Blavatskaia, D.E.D., "The use of intralamellar homoplasty in order to reduce refraction of the eye" Uberstzt. Aus. Ofalmol. Zh. (1966) 7:530-537 which was apparently translated to Arch. Soc. Ophthmol. Optom. (1988) 6:31-325. A complete English translation was previously enclosed.
Mathis Mark
Silvestrini Thomas
Jones Mary Beth
KeraVision Inc.
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