Abstract:
A lens for refractive tear shaping, having a curved lens body with a peripheral edge and a central opening therein. The central opening is shaped and sized and has a tear shaping edge structured to form a tear meniscus within the central opening. The tear meniscus being formed by interaction of a tear film of the eye and the tear shaping edge and having a posterior curvature conforming to an anterior corneal curvature and an anterior curvature. The anterior curvature is dependent on the size and shape of the central opening and structure of the tear shaping edge.

Description:
FIELD OF THE INVENTION 
     The invention generally relates to contact lenses and refractive correction by applications of contact lenses or other structures to the eye. 
     BACKGROUND OF THE INVENTION 
     Known contact lenses generally cover virtually all of the cornea or cover the cornea centrally while leaving a portion of the peripheral cornea uncovered. Contact lenses known to the Applicant achieve refractive correction because of the optical nature of an optically transparent, rigid, semi-rigid or flexible material that refracts light and thus alters the refraction of light striking the cornea and passing through the other optical parts of the eye to an image formed on the retina. 
     The concept of a tear lens is known to exist in the context of conventional contact lenses. The tear lens is formed by a layer of tears bounded on an anterior surface by the back of a contact lens optical zone and at a posterior surface of the tear lens by the surface of the corneal epithelium. A tear lens, as understood in this conventional sense, contributes to refractive correction primarily in the context of rigid contact lenses. This is because the posterior surface of the rigid contact lens maintains its shape and curvature independent of the shape of the cornea and affects the focusing of light in addition to the refractive power of the contact lens. While a tear lens technically exists in the context of flexible or soft contact lenses, the effect of the tear lens on refraction is negligible because of the general conformity of the soft contact lens shape to the shape of the cornea. 
     Numerous possible complications are known to exist with use of contact lenses on the cornea even though modern contact lenses cause fewer complications than contact lenses of decades ago. The presence of contact lenses can lead to stasis and entrapment of the tear film which can lead to an accumulation of corneal epithelial waste products in the entrapped tear film. Corneal epithelial waste products in high enough concentrations can be toxic to the cells of the corneal epithelium. Mechanical interaction between the posterior surface of the contact lens and the corneal epithelium can lead to abrasion or distortion. Entrapment of solid objects, however tiny between the posterior surface of the contact lens and the anterior corneal epithelium can also lead to corneal epithelial abrasion. Under some circumstances, the reduction of oxygen available to the corneal epithelium by having the barrier of the contact lens between the corneal epithelium and the atmosphere can lead to health complications for the corneal epithelium as well. 
     There is still room for improvement in the arts of refractive correction by application of lenses to the eye. 
     SUMMARY OF THE INVENTION 
     The invention solves many of the above stated problems by providing a lens having a central opening which centers on the optical axis of the eye. The central opening is structured such that capillary action forms a meniscus of tears in the opening. According to an example embodiment of the invention, the inventive lens is structured so that a concave meniscus is formed. The concave meniscus is provided for correction of myopia. It is expected that a concave meniscus will form in a relatively larger diameter opening according to embodiments of the invention. 
     According to another example embodiment of the application, a convex meniscus is formed. A convex meniscus is expected to form in a case of a smaller diameter opening in the lens which generally overlies the optical axis of the eye. 
     According to another example embodiment of the invention, the opening is non-circular in structure. For example, an oval opening is expected to create a meniscus having a first curvature in a first axis and a second curvature in a second axis and thereby permitting correction of astigmatism by the tear meniscus formed. According to example embodiments of the invention, the central opening may be oval in shape or polygonal having a first axis longer than a second axis to achieve the astigmatic correction. 
     According to example embodiments of the invention, the cross-sectional shape of the edge or periphery of the opening may vary when viewed in cross-section. 
     According to an example embodiment, the cross-sectional shape of the periphery of the opening may demonstrate a thick rim. According to another example embodiment, the cross-sectional shape of the periphery of the opening may demonstrate the thin rim. 
     According to another embodiment, the cross-sectional shape of the periphery of the opening may demonstrate a straight rim. The straight rim may be substantially radial in orientation as compared to the curvature of the lens and opening or may be tilted to create an acute or obtuse angle relative to a tangent to the corneal surface. 
     According to another example embodiment of the invention, the periphery of the opening may demonstrate a concave shape when viewed in cross section. 
     According to another example embodiment of the invention, the periphery of the opening may demonstrate a convex shape when viewed in cross section. 
     According to another example embodiment of the invention, the cross-sectional shape of the periphery of the opening may demonstrate a polygonal cross-section which may be either concave or convex. 
     According to other example embodiments of the invention, the cross-sectional shape of the rim may vary around the circumference of the periphery of the opening. For example, a portion or portions of the periphery of the opening when viewed in cross-section may be concave while other portions may be convex. 
     According to another example embodiment of the invention, the perimeter of the rim may vary in shape when viewed in an anterior-posterior direction. 
     According to another example embodiment of the invention, the perimeter of the rim viewed anterior to posterior may have a smooth continuous curved shape. 
     According to another example embodiment of the invention, the perimeter of the rim when viewed anterior to posterior may include indentations in the rim perimeter. 
     According to another example embodiment of the invention, the rim perimeter may include appendages extending inwardly from the rim. 
     According to another example embodiment of the invention, the periphery of the opening when viewed in an anterior to posterior direction may have a circular shape. According to another example embodiment of the invention, the periphery of the opening when viewed in an anterior to posterior direction may have an oval shape and according to another example embodiment of the invention, the periphery of the opening in viewed in an anterior to posterior direction may have a polygonal shape. The polygonal shape may include a regular polygon or an irregular polygon shape. The polygon may be generally radially symmetrical or may be other than radially symmetrical. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is an anterior to posterior view of a lens for refractive tear shaping having a circular central opening therein; 
         FIG. 2  is an anterior to posterior view of a lens for refractive tear shaping having an oval central opening therein; 
         FIG. 3  is a lens for refractive tear shaping having a polygonal opening therein; 
         FIG. 4  is an anterior to posterior view of a lens for refractive tear shaping having a stellate opening with indentations according to an example embodiment of the invention; 
         FIG. 5  is an anterior to posterior view of a lens for refractive tear shaping having a stellate opening with appendages according to an example embodiment of the invention; 
         FIG. 6  is an anterior to posterior view of a lens for refractive tear shaping having a generally rectangular polygonal opening therein according to an example embodiment of the invention; 
         FIG. 7  is a cross-sectional view of a lens for refractive tear shaping in situ on a cornea and with a concave tear meniscus according to any example embodiment of the invention; 
         FIG. 8  is a cross-sectional view of a lens for refractive tear shaping in situ on a cornea with a convex tear meniscus according to an example embodiment of the invention; 
         FIG. 9  is a cross-sectional view of a lens for refractive tear shaping in situ on a cornea with a central opening having inward angled edges and a concave tear meniscus according to an example embodiment of the invention; 
         FIG. 10  is a cross-sectional view of a lens for refractive tear shaping in situ on a cornea with a concave tear meniscus and outwardly angled edges according to an example embodiment of the invention; 
         FIG. 11  is a cross-sectional view of a lens for refractive tear shaping having an opening with concave peripheral edges according to an example embodiment of the invention with the tear meniscus not depicted; 
         FIG. 12  is a cross-sectional view of a lens for refractive tear shaping having an opening with convex peripheral edges in situ on a cornea according to an example embodiment of the invention with the tear meniscus not depicted; and 
         FIG. 13  is a lens for refractive tear shaping in situ on a cornea with an opening having polygonal peripheral edges with the tear meniscus not depicted. 
     
    
    
     DETAILED DESCRIPTION 
     Referring to  FIGS. 1-13 , the invention is directed to lens for refractive tear shaping  20  wherein refractive correction is achieved or enhanced by the shaping of the tear film. 
     Referring particularly to  FIGS. 1-6 , lens for refractive tear shaping  20  according to an example embodiment of the invention generally includes lens body  22  having peripheral edge  24  and defining central opening  26 . Central opening  26  is surrounded by a tear shaping edge  28 . According to the depicted embodiment, tear shaping edge  28  defines circular central opening  30 . Tear shaping edge  28  can have a number of cross sectional structures and shapes as described below. 
     Referring now to  FIG. 2 , another embodiment of lens for refractive tear shaping  20  is depicted. The depicted embodiment includes lens body  22  having peripheral edge  24  and elliptical or oval central opening  32 . Elliptical or oval central opening  32  is bounded by tear shaping edge  28 . 
     Referring to  FIG. 3 , another embodiment of lens for refractive tear shaping  20  is depicted having polygonal central opening  34 . Polygonal central opening  34  is depicted as an irregular hexagon, however polygonal central opening  34  may have more or less than six sides and six vertices. 
     Referring particularly to  FIGS. 2 and 3 , elliptical or oval central opening  32  and polygonal central opening  34  may have long axis  36  and short axis  38 . 
     Referring now to  FIG. 4 , according to another embodiment, lens for refractive tear shaping  20  defines stellate opening  40  having indentations into the material of the lens surrounding stellate opening  40 . While stellate opening  40  is depicted as circularly symmetrical, stellate opening  40  may also have long axis  36  and short axis  38 . 
     Referring now to  FIG. 5 , another embodiment of lens for refractive tear shaping  20  is depicted. According to the depicted embodiment, stellate opening with appendages  44  is depicted. Appendages  46  extend inwardly from outer edge  48 . While depicted as circularly symmetrical, stellate opening with appendages  44  may also have long axis  36  and short axis  38 . 
     Referring now to  FIG. 6 , lens for refractive tear shaping  20  with rectangular opening  50  is depicted. Rectangular opening  50  is depicted having a particular proportional aspect ratio, however this should not be considered limiting as the aspect ratio of rectangular opening  50  may be altered by altering the length of long axis  36  as compared to short axis  38 . 
     Referring now to  FIGS. 7-13 , cross-sectional views of example embodiments of lens for refractive tear shaping  20  are depicted. 
     Referring particularly to  FIG. 7 , an embodiment of the invention including parallel tear shaping edge  52  is depicted. It is noted that lens body  22  in the embodiment depicted in  FIG. 7  that parallel tear shaping edge  52  is generally parallel on opposing sides of central opening  26 . Also depicted in  FIG. 7  is concave tear meniscus  54 . Concave tear meniscus  54  affects a negative refractive power due to its concave shape and is expected to contribute focusing power for correction of myopia. It is expected that the concavity of concave tear meniscus  54  will vary with the size of central opening  26  and with the depth  56  of tear shaping edge  28 . 
     It is expected that to a certain point smaller diameter of central opening  26  will create a more steeply curved concave tear meniscus imparting greater negative refractive power and stronger correction for myopia. It is also expected that increasing depth  56  of tear shaping edge  28  will increase negative refractive power to a certain degree. As discussed above, central opening  26  may have various shapes, some of which include a long axis  36  and short axis  38 . 
     It is expected that by judicious selection of the size of long axis  36  and short axis  38  that astigmatism may be corrected by creating a concave tear meniscus  54  having different shape and therefore differing power on various meridians. 
     Referring now to  FIG. 8 , lens for refractive tear shaping  20  having parallel tear shaping edge  52  is sized and configured to create convex tear meniscus  58 . It is expected that when the size of central opening  26  is reduced to a sufficient degree, convex tear meniscus  58  will be formed in central opening  26 .  FIG. 8  depicts parallel tear shaping edge  52  along with a smaller diameter central opening  26  than does  FIG. 7 . It is expected that when the size of central opening  26  and depth  56  of tear shaping edge are appropriate convex tear meniscus  58  will be formed. 
     Referring now to  FIG. 9 , lens for refractive tear shaping  20  with anterior acute tear shaping edge  60  is depicted. It is noted that anterior acute tear shaping edge  60  is arranged so that tear shaping edge  28  narrows from posteriorly-to-anteriorly. Concave tear meniscus  54  is also depicted. It is expected that anterior acute tear shaping edge  60  will create a more concave tear meniscus  54  thus, creating greater negative refractive power to concave tear meniscus  54 . 
     Referring now to  FIG. 10 , lens for refractive tear shaping  20  having anterior obtuse tear shaping edge  62  is depicted. Anterior obtuse tear shaping edge  62  is structured so that central opening  26  is wider anteriorly and narrower posteriorly. It is expected that anterior obtuse tear shaping edge  62  will create a flatter concave tear meniscus  54  as depicted in  FIG. 10  thus, creating a concave tear meniscus having less negative refractive power than parallel tear shaping edge  52  having a similar posterior diameter. 
     Referring now to  FIG. 11 , lens for refractive tear shaping  20  having concave tear shaping edge  64  is depicted. In  FIG. 11 , no tear meniscus  66  is depicted for clarity. Concave tear shaping edge  64  includes anterior edge  68 , posterior edge  70  and concave portion  72 . 
     Referring now to  FIG. 12 , lens for refractive tear shaping  20  with convex tear shaping edge  74  is depicted. No tear meniscus  66  is depicted for clarity. In the depicted embodiment, convex tear shaping edge  74  has a radius of curvature approximately equal to half of depth  56  of tear shaping edge  20 . This should not be considered limiting however as the radius of curvature of convex tear shaping edge  74  may vary. 
     Referring now to  FIG. 13 , lens for refractive tear shaping  20  with faceted tear shaping edge  76  is depicted. Faceted tear shaping edge  76  presents anterior edge  78 , posterior edge  80  and internal angle portion  82 . 
     Lens for refractive tear shaping  20  according to the various embodiments described herein may be formed from hydrogel polymers of the types used in soft contact lens that are now available or any hydrogel polymer materials to be developed in the future. Hydrogel polymers are generally water absorbent and hydrogel polymers may be used to manufacture lenses for refractive tear shaping  20  according to the invention by methods including but not limited to lathe cutting, cast molding, spin casting and injection molding. Lenses for refractive tear shaping  20  may also be manufactured from rigid oxygen permeable materials by known manufacturing processes including lathe cutting. It is to be understood that lens for refractive tear shaping  20  may be manufactured by any known contact lens manufacturing process or contact lens manufacturing processes to be developed in the future. 
     Lenses for refractive tear shaping  20  are expected to be made in diameters ranging from approximately 5 mm to 16 mm. Certain features of lens for refractive tear shaping  20  such as central opening  26  diameter, the structure of tear shaping edge  28 , the appropriate length of long axis  36  and short axis  38  to achieve desired refractive correction are expected to be developed with a certain degree of experimentation. It is expected that this degree of experimentation will not be undue and that those of ordinary skill in the art based on the present application disclosure will be able to engage in such experimentation without significant difficulty. 
     It is expected that for formation of concave tear meniscus  54 , that smaller diameter central openings  26  will result in higher refractive power of concave tear meniscus  54 , thus permitting higher degrees of refractive correction for myopia. It is also expected that when the diameter of central opening  26  becomes sufficiently small, tear meniscus  66  will transition from concave tear meniscus  54  to convex tear meniscus  58 . Determination of this transition diameter for transition is expected to be achievable by reasonable levels of experimentation. 
     The effect of depth  56  of tear shaping edge  28  on refractive power of tear meniscus  66  also should be determinable by reasonable experimentation. It is expected that greater depth  56  will generally create a thicker periphery of tear meniscus  66  resulting in higher degrees to concavity of concave tear meniscus  54  and greater myopic correction. 
     Further, understanding of the effect of other features of the disclosed lenses including anterior acute tear shaping edge  60 , anterior obtuse tear shaping edge  62 , concave tear shaping edge  64 , convex tear shaping edge  74  and faceted tear shaping edge  76  are expected to be achieved by reasonable experimentation well within the ability of one of ordinary skill in the art. It is expected that such experimentation will not be undue. It is also expected that the effect of stellate opening  40  with indentations  42  as well as stellate opening with appendages  44  and appendages  46  can also be determined experimentally. 
     The present invention may be embodied in other specific forms without departing from the spirit of the essential attributes thereof; therefore, the illustrated embodiments should be considered in all respects as illustrative and not restrictive, reference being made to the appended claims rather than to the foregoing description to indicate the scope of the invention.