Corneal prosthesis

#This invention relates to corneal prostheses used to replace all or part of the cornea of an eye.

#Many researchers have designed corneal prostheses and hundreds have been implanted. Pellier de Quengsy is credited with first suggesting the insertion of a glass plate into the cornea in 1771. These various designs met with varying degrees of early success, some with initial enthusiasm, and generally by disillusionment as the long-term complications occurred. Barber J. C., International Ophthalmology Clinics, 28:103-09 (1988).

#Early corneal prosthesis designs involved imbedding a flat disk of alloplastic material into the cornea with a hole anterior to the prosthesis. Spool-shaped optical lenses were then placed in the hole through the cornea and the prosthesis. Another early design was an optical core held by plates attached to the core and engaging the anterior and posterior surfaces of the cornea. The posterior plate was inserted through an opening formed in the cornea, with a trephine and a relaxing incision which was the source of considerable complications.

#Other details, objects and advantages of the present invention will become more readily apparent from the following description of the presently preferred embodiments thereof.

#In the accompanying drawings, preferred embodiments of the present invention are illustrated, wherein

#FIG. 1 is an elevational view of a preferred embodiment of the present invention;

#Referring to FIGS. 1 and 2, the corneal prosthesis is illustrated having an optical core member 10 and a skirt member 20. The core member 10 is made of an alloplastic material and preferably intraocular grade polymethylmethacrylate. The optical member 10 is of a substantially frustoconical shape with a posterior substantially conical section 11, and preferably an anterior substantially cylindrical section 12 with a length of 0.8 to 1.2 millimeters. A first anterior end portion 13 is integral with the anterior cylindrical section 12, and a second posterior end portion 14 is integral with the posterior cone section 11. The first anterior end portion 13 has an optical surface 15 acting as a lens, and has an anterior flange 16 extending at least 0.5 millimeter and preferably less than 1.0 millimeter beyond the periphery of the anterior section 12. The posterior conical section 11 has an integral second posterior end portion 14 having an optical surface 17. The core member 10 is typically about 8 millimeters in length, sufficient to avoid the retroprosthesis membrane from growing over the optical surface 17 of the second posterior end portion 14.

#A peripheral groove 18 is preferably provided in the optical core member 10 between the posterior cone section 11 and the anterior cylindrical section 12. The groove 18 is capable of holding the skirt member 20 in position peripheral about the optical core member 10 without the use of adhesive material. Groove 18 is preferably 0.25 to 0.50 millimeter deep, and 0.15 to 0.30 millimeter wide depending on the thickness of skirt member 20. Preferably the width of groove 18 is less than 0.05 millimeter larger than the thickness of the skirt member 20.

#Skirt member 20 is made of a hydrophilic, porous semi-flexible material capable of vascular invasion and formation of fibrous tissue within the matrix of the material when implanted into an intralamellar pocket in the cornea of an eye. The skirt member 20 is preferably made of a material selected from the group consisting of porous polytetrafluoroethylene, porous polytetrafluoroethylene carbon and porous polytetrafluoroethylene aluminum oxide fibers (trade name Proplast), with polytetrafluoroethylene aluminum oxide fibers being the most preferred. Proplast has been made by Vitek, Inc. in Houston, Tex., and is described in U.S. Pat. Nos. See U.S. Pat. Nos. 3,992,725, 4,118,532, 4,129,470 and 4,209,480.