Abstract:
A dry-eye treatment method includes collecting fluid from the inside of the eye and transporting the collected fluid into the eyelid fornix, where it accumulates. At each blink, accumulated fluid from the fornix is spread across the surface of the eye.

Description:
RELATED APPLICATIONS  
       [0001]     This application claims priority under 35 U.S.C. §119 to the U.S. Provisional Patent Applications 60/565,009, filed Apr. 23, 2004 and 60/626,190, filed Nov. 9, 2004. 
     
    
     FIELD OF INVENTION  
       [0002]     The invention relates to treatment of dry eye syndrome.  
       BACKGROUND  
       [0003]     The surface of the eye is constantly bathed in tears. Without this coating of tears, the eye would dry out and vision would decrease drastically. An insufficient supply of tears results in a condition known as “dry-eye syndrome.” 
         [0004]     A variety of treatments are available for dry-eye syndrome. The particular treatment to be used in any one case is selected on the basis of the specific etiology.  
         [0005]     One such treatment involves the application of eye drops to provide temporary relief of dry-eye syndrome. In most cases, eye drops are periodically reapplied. This can be inconvenient, particularly if the need to reapply eye drops occurs too frequently. In addition, many patients are uncomfortable with maneuvering a dropper close to the surface of the eye and keeping the eyes open to allow the eye drop to reach the surface of the eye. In severely dry eyes, even application of drops is ineffectual.  
       SUMMARY  
       [0006]     A method for treating severely dry-eye syndrome includes draining fluid from inside the eye into the fornix of the eye at a rate selected such that, with each blink, fluid accumulated in the fornix is spread over the eye.  
         [0007]     A method for treating dry-eye syndrome includes collecting fluid from inside the eye; and transporting the collected fluid into the fornix of the eyelid.  
         [0008]     In some practices of the invention, transporting the collected fluid includes transporting the fluid at a rate selected such that, with each blink, fluid accumulated in the fornix is spread over the eye.  
         [0009]     In other practices of the invention, collecting fluid includes collecting fluid from the interior of the eye. For example, fluid can be collected from the anterior chamber of the eye.  
         [0010]     Practices of the invention also include those in which wherein collecting fluid includes inserting a first end of a tube into the anterior chamber of the eye. Optionally, a jacket defining a cavity is placed on the surface of the eye, and a second end of the tube is placed in fluid communication with the cavity.  
         [0011]     In those practices in which a tube is used to collect fluid from inside the eye, a pressure-relief valve can be provided at any place between the two ends of the tube or at the ends themselves. Optionally, a pressure threshold associated with the pressure-relief valve can be set on the basis of a fluid pressure in the anterior chamber. In yet another optional practice of the invention, the pressure-relief valve is enclosed in a jacket.  
         [0012]     In another aspect, the invention includes a method for treating dry-eye syndrome, by causing the eye to be bathed by fluid produced within the eye.  
         [0013]     In some practices, causing the eye to be bathed includes transporting fluid produced within the eye from inside the eye to outside the eye.  
         [0014]     Other practices further include causing the transported fluid to accumulate at a location outside the eye. One location that can be used is the fornix.  
         [0015]     In another aspect, the invention includes an apparatus for treating dry-eye syndrome. Such an apparatus includes means for extracting fluid from inside the eye; and means for directing the fluid to accumulate at a location outside the eye.  
         [0016]     In some embodiments, the means for extracting fluid includes a tube having a first end for insertion inside the eye, and a second end for remaining outside the eye; and a pressure-relief valve coupled to the second end. Optionally, a jacket can enclose the pressure relief valve.  
         [0017]     In other embodiments, the means for directing fluid includes a tube configured to direct fluid to the fornix of the eye.  
         [0018]     Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. Although methods and materials similar or equivalent to those described herein can be used in the practice or testing of the present invention, suitable methods and materials are described below. All publications, patent applications, patents, and other references mentioned herein are incorporated by reference in their entirety. In case of conflict, the present specification, including definitions, will control. In addition, the materials, methods, and examples are illustrative only and not intended to be limiting.  
         [0019]     These and other features and advantages of the invention will be apparent from the following detailed description and the accompanying figures, in which: 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0020]      FIG. 1  is a jacketed shunt with a drainage duct; and  
         [0021]      FIG. 2  is a jacketed shunt with a drainage duct for drainage into the fornix behind the lower lid of the eye. 
     
    
     DETAILED DESCRIPTION  
       [0022]     A shunt  10  for treatment of dry eye syndrome, shown in  FIG. 1 , includes a valve  12  having a valve inlet  14  and a valve outlet  16 . The valve  12  is a pressure-regulating valve that opens its outlet  16  whenever the fluid pressure at its inlet  14  is in excess of a pre-determined threshold. An exemplary valve  12  of this type is the Ahmed valve, which is manufactured by New World Medical, Inc. of Rancho Cucamonga, Calif.  
         [0023]     A silicone rubber jacket  26  encloses the valve  12  so that fluid from the outlet  16  collects in a cavity  28  defined by the jacket  26 . Materials other than silicone rubber can be used to form a jacket  26  around the valve  12 . Preferably the jacket material is biocompatible and/or impervious to water.  
         [0024]     To provide drainage for the cavity, the shunt  10  includes a drainage duct  30  having a proximal end  32  and a distal end  34 . The proximal end  32  of the drainage duct  30  is placed in fluid communication with the cavity  28 . The distal end  34  is inserted into fornix of the lower eyelid.  
         [0025]     In operation, the jacket  26  is implanted onto the surface of the sclera of the eye. An open proximal end of the intake duct  22  is inserted into the anterior chamber of the eye. Fluid, under pressure, fills the intake duct  22 . When the pressure exceeds the pre-defined threshold, the valve outlet  16  opens. This causes the fluid to pass out of the valve  12  and into the cavity  28 . This fluid eventually accumulates in the fornix.  
         [0026]     For treatment of dry eye syndrome, the pre-defined threshold for opening the value outlet  16  is set so that normal pressure is sufficient to open the valve and pass fluid into the drainage shunt  30  that drains into the fornix. This results in an accumulation of fluid in the fornix. Each time the patient blinks, the fluid collected in the fornix is spread over the surface of the eye, thereby relieving dry-eye syndrome.  
         [0027]     The pressure threshold is selected such that fluid drains into the fornix quickly enough to accumulate into a pool having sufficient volume to be spread across the eye surface, but not so fast as to overflow the fornix or to drain the anterior chamber.  
         [0028]     It is to be understood that while the invention has been described in conjunction with the detailed description thereof, the foregoing description is intended to illustrate and not limit the scope of the invention, which is defined by the scope of the appended claims. Other aspects, advantages, and modifications are within the scope of the following claims.  
         [0029]     Having described the invention, and a preferred embodiment thereof, what I claim as new, and secured by letters patent is: