Prosthesis (i.e. – artificial body members) – parts thereof – or ai – Eye prosthesis – Corneal implant
Reexamination Certificate
2000-04-10
2001-07-03
Nguyen, Dinh X. (Department: 3738)
Prosthesis (i.e., artificial body members), parts thereof, or ai
Eye prosthesis
Corneal implant
C623S005110, C128S898000
Reexamination Certificate
active
06254637
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates in general to an artificial cornea and an implantation thereof. More particularly, the present invention relates to an artificial cornea capable of preventing a separation thereof from an eyeball of the patient during an implant operation thereof while avoiding post-operative complications at the interface between the artificial cornea and the patient's cornea, such as erosive tissue necrosis (melting), leakage of aqueous humor, infection, extrusion of the implant, and intraocular inflammation.
2. Description of the Prior Art
Corneas severely scarred due to thermal or chemical burns, heavily vascularized or vesiculated corneas, or corneas of ocular pemphigoid may be progressed to dry eye syndromes such as StevensJohnson syndrome, so that they may be severely injured, thereby losing vision.
Although such injured corneas may recover vision by the transplantation of human homologous corneal tissue, the transplantation of such human homologous corneal tissue exhibits a high probability of failure. For this reason, the implantation of an artificial cornea has been highlighted.
Moreover, in the case where the transplantation of human homologous corneal tissues is basically impossible or has been repeatedly failed, the implantation of an artificial cornea ultimately becomes a unique way to recover vision.
Up to date, there have been many efforts in the research and development for materials and designs of artificial corneas. In the 1950's, cornea implant operations using an acrylic resin as an artificial cornea were proposed. In the 1960's, Cardona, who played an important role in the research of artificial corneas, developed a bolt and nut type artificial cornea, which has been used until recently.
Necessity and importance for research and development of artificial corneas are as follows:
A. Technical Aspects
In the cases of severe dry eye conditions, thermal or chemical burns of corneas, ocular pemphigoid, Stevens-Johnson syndrome, and a repeatedly failed cornea implantation, the transplantation of human homologous corneal tissues exhibits a low possibility to recover vision. In such cases, therefore, the implantation of an artificial cornea should be taken into consideration, as an ultimate method for achieving an improvement in vision. However, all artificial corneas developed up to now have many drawbacks. For this reason, the development of an artificial cornea having an approved stability and utility, has been strongly required in the world.
B. Economical and Industrial Aspects
In the case of various intractable corneas, to which a transplantation of homologous corneal tissues is impossible, the implantation of an artificial cornea is the ultimate way to recover vision. However, many countries have no ability to manufacture such an artificial cornea. For this reason, all artificial corneas available in those countries are those manufactured by and imported from advanced countries, including U.S.A. and France, having an ability to manufacture those artificial corneas. However, such artificial corneas are very expensive because they are patented products. In spite of such high costs, most of the currently available artificial corneas exhibit a limited success even after repeated implant operations, and furthermore cause various complications resulting in blindness. This increases medical expenses of individuals and nations, and also results in the high loss of labor.
C. Social and Cultural Aspects
In advanced countries, artificial corneas were researched and developed for the treatment of intractable corneas to which homologous corneal tissues could not be implanted. However, in Korea, there is another reason for the urgent development of artificial corneas. That is, donor corneas necessary for the implantation of homologous corneal tissues are in great shortage in Korea because most Korean people do not want to donate organs after death due to traditional Confucian ideas. For this reason, there are many patients who can recover vision even by the implantation of homologous corneal tissues, and maintain a normal social life. In this regard, if more stable artificial corneas are developed, it is then expected that many patients suffering from the corneal disorder can easily recover vision and return to a functional and productive role in society.
Artificial corneas developed up to now involve two main failures. One failure is a structural failure, that is, a separation of the artificial cornea from the peripheral tissue due to an instable graft of the artificial cornea to the peripheral tissue. Another failure is a functional failure caused by the fact that tissues with cicatricial pemphigoid cover the optical part of eye.
In order to overcome such failure factors of artificial corneas, the inventor has made active research for the design of artificial corneas, the surface treatment of artificial cornea components such as optical and support parts, the implant operation method, and the treatment conducted after the implant operation. By virtue of such research, the inventor could determine optimum conditions capable of providing an artificial cornea having a maximum biocompatibility and a stability. In particular, the maximum biocompatibility and stability of the artificial cornea was established, based on experiments conducted with animals. The experimental results may be used as fundamental materials for future clinical demonstrations and industrial applications in order to achieve an improvement in medical technology.
SUMMARY OF THE INVENTION
It is therefore an object of the present invention to overcome the above mentioned failure factors, and to provide an artificial cornea exhibiting a maximum biocompatibility and a high stability, along with an effective implantation method for the artificial cornea.
In accordance with one aspect, the present invention provides an artificial cornea comprising: an artificial cornea body having, at a lower portion thereof, a cylindrical portion adapted to be arranged in the interior of a patient's eyeball, and, at an upper portion thereof, an optical portion adapted to be exposed through an anterior portion of the patient's eyeball, the optical portion having a diameter less than that of the cylindrical portion to define a step at a lower end thereof; a skirt fitted around the optical portion of the cornea body and seated on the step; an anterior flange coupled to an upper surface of the skirt; and a support member attached to a lower end of the cylindrical portion and adapted to support the artificial cornea body.
In accordance with another aspect, the present invention provides a method for implanting the above mentioned artificial cornea to a cornea of a patient's eye, comprising the steps of: preparing a human amnion, and maintaining the prepared human amnion in an antibiotic state; subjecting the patient's cornea to a 360 conjunctival incision; suturing a Flieringa fixation ring at four positions to the sclera exposed through the incised conjunctiva, thereby fixing the Flieringa fixation ring to the sclera; peeling off the epithelium of the patient's cornea; conducting a partial trephination for the resultant patient's cornea, thereby forming, in the patient's cornea, a central orifice having a depth corresponding to about ½ to ⅓ of the thickness of the patient's cornea; subjecting the resultant patient's cornea to a 360 intralamellar incision to a desired width, thereby forming a corneal pocket adapted to subsequently receive the skirt of the artificial cornea; subjecting the resultant patient's cornea to a partial trephination along the central orifice; incising the anterior sac of the crystalline humor along an orifice formed after the partial trephination, and then removing the lenticular nucleus; conducting an anterior vitrectomy for the resultant patient's cornea while sucking the lenticular cortex and posterior sac; sufficiently filling a Viscoat in the eyeball; i
Lee Jin Hak
Lee Moo Suk
Wee Won Ryang
Jones Tullar & Cooper P.C.
Lucid Korea Co., Ltd.
Nguyen Dinh X.
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