Abstract:
A reduced profile eyelid weight longer and wider than traditional eyelid weights but thinner so as to provide a less protruding profile.

Description:
FIELD 
     The present invention relates to a system for the treatment of lagophthalmos and, more particularly, to an eyelid weighting device for improving eyelid closure and reduced profile for a less conspicuous implant. 
     BACKGROUND 
     A number of different eyelid closure systems exist for facial paralysis. Surgical procedures, such as tarsorrhaphy (suturing the corners of the eyelids together) and implanting various prosthetic devices in the eyelids may be used to improve eyelid closure and reduce exposure of the eye. This provides some protection but generally prevents eyelid closure, reduces peripheral vision, and may be cosmetically unattractive. Prosthetic devices such as tantalum gauze mesh, silicon rubber elastic strips, stainless steel springs and magnets implanted in the upper and lower lids provide some amount of active eyelid closure. 
     Gold weight implants are also used in the surgical treatment of facial paralysis. The gold weights are implanted in the upper eyelid and secured to either the tarsal plate, orbital septum, or levator aponeurosis. When the levator muscle is relaxed, the upper eyelid is lowered by the force of gravity. One problem with the implants is the noticeable protrusion through the skin of the eyelid, an undesirable cosmetic effect. U.S. Pat. No. 5,543,437 discloses a standard profile weight. What is needed is an implant with a reduced profile. Although the profile is reduced the implant must maintain the same weight in order t o properly lower the eyelid. 
     SUMMARY 
     It is a general object of the invention to provide a reduced profile eyelid weight. It is a further object of the present invention to provide an eyelid weight with a reduced profile yet with a useable range of weight for eyelid closure. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     Additional advantages of the invention will become apparent upon reading the following detailed description and upon reference to the drawings, in which: 
     FIG. 1 is a top plan view of an eyelid weighting device in accordance with the present invention. 
     FIG. 2 is a cross-sectional view taken along line  2 — 2  in FIG.  1 . 
     FIG. 3 is a cross-sectional view taken along line  3 — 3  in FIG.  1 . 
     FIG. 4 a  and  4   b  are schematic views showing the placement of the weighting device when implanted in the eyelid. 
    
    
     DETAILED DESCRIPTION 
     The exemplary embodiments are described herein with reference to specific configurations and protocols. Those skilled in the art will appreciate that various changes and modifications can be made to the exemplary embodiments while remaining within the scope of the present invention. This invention incorporates by reference the teaching in U.S. Pat. No. 5,543,437. 
     A first embodiment is described with reference to FIGS. 1 to  4   b.  An eyelid weighting device or implant  10  incorporating the invention is shown in FIGS. 1-3. The implant  10  is a bar with an outer surface  12  and a concave inner surface  13 . The concave surface  13  has a substantially spherical curvature which conforms to the curvature of the eyeball or globe  6 . The outer surface  12  preferably follows the general shape of the inner surface  13  as shown to reduce the visibility of the implant  10  in the eyelid. In the preferred form the concave surface  13  has a radius of curvature of between approximately 11.5 to 13.5 mm, for example approximately 12.7 mm. 
     When the weighting device  10  is implanted in an eyelid  8 , the spherical shape of inner surface  13  provides for substantially unrestrained movement of the implant  10  across the surface of the eye when the lid is opened and closed. With the concave surface  13  the inducement of astigmatism is minimized and the implant  10  is more comfortable for the patient as the weight of the implant  19  is not concentrated at the edges of the implant  10 , but is instead evenly distributed across the area of the eye beneath the surface  13 . Eyelid closure without induced astigmatism is made more effective by the spherical shape of surface  13 , protecting the eye from dryness, irritation and other potentially damaging conditions. 
     Implant  10  has a pair of spaced, first and second major edges  15  and  16  and a pair of side edges  18  and  19 . The first major edge  15  has contoured ends  21  and  22  which are curved upward and outward toward the side edges  18  and  19 . The radius of curvature of the contoured ends is preferably in the range of approximately 2 to 3.5 mm. Providing the first major edge  15  with contoured ends reduces the surface area of the inner and outer surfaces  12  and  13  so that the implant is less visible in the eyelid. The first major edge  15  is also tapered as shown in FIG.  3 . Reducing the thickness of the implant along the first major edge further lowers the profile of the implant within the lid where the eyelid skin is thinnest. The spherical-shaped implant  10  is less noticeable, a feature that is particularly desirable for the more self-conscious patient. 
     The edges  15 ,  16 ,  18  and  19  are preferably rounded or smoothed to remove any sharpness and minimize the risk that the implant will extrude through the surface of the lid. Providing the edges of the weighting device  10  with a smooth finish also enhances the comfort of the implant. 
     One or more apertures  24  are formed in the weighting device  10  as shown in FIG.  1 . The apertures may be used to anchor the implant  10  to the orbital septum or tarsus, placing it securely parallel to the eyelid margin, depending upon the final placement of the implant in the lid. Sutures may be inserted through one or more of the apertures  24  and fixed to the appropriate tissues. A suture through a second or third aperture may be required to ensure secure placement parallel to the eyelid margin. After time, the placement of the implant  10  is further stabilized by tissue growth through the apertures  24 . The number of apertures formed in implant  10  may vary, although three apertures are generally suitable for implants with dimensions of 11.3 mm to 18.2 mm in length and 5.5 to 6.5 mm in height. 
     The implant  10  has a thickness of approximately 0.5 to 0.7 mm, and a width of approximately 5 to 7 mm. The nominal length of the implant varies depending upon the weight of the implant and the material from which the implant is fabricated. Suitable materials include gold or platinum. Gold is preferred due to its high specific gravity and color. Platinum is preferred if there is an allergic reaction to gold. The most useful weights vary from 0.6 to 1.6 grams. 
     The weighting device  10  is implanted using the appropriate surgical techniques. The placement of the implant  10  may be septal (FIG. 4 a ) or pretarsal (FIG. 4 b ) depending on the preference of the surgeon and the needs of the patient. Septal placement is often preferred as the implant is less conspicuous, although some prefer lower pretarsal placement. When fixed to the orbital septum the implant is oriented with the first major edge  15  facing downward as shown particularly in FIG. 4 a.  The first major edge  15  may face upward, as shown in FIG. 4 b,  or downward when the implant  10  is secured to the tarsus. Orienting the implant  10  as described ensures that the contoured ends  21  and  22  and the tapered portion of the implant are situated in the thinnest portion of the eyelid. 
     Having disclosed exemplary embodiments and the best mode, modifications and variations may be made to the disclosed embodiments while remaining within the scope of the present invention as defined by the following claims.