Abstract:
The lens of the subject corrective eyeglasses obstructs the vision of a preselected area but not the whole of the wearer&#39;s stronger eye, either by impairing his vision or entirely blocking it. When the vision is so obstructed, the wearer&#39;s weaker eye is forced to compensate for the stronger eye&#39;s loss by taking over the area of sight not visible by the stronger eye. The lens may be obstructed by applying over the preselected area of the lens a coating which distorts or blurs the object seen by the eye. Alternatively an opaque coating may be applied to the preselected area to entirely block the object. In either case, the wearer is forced to use his weaker eye to see the object impaired or blocked by the coating.

Description:
FIELD OF THE INVENTION 
       [0001]    This invention relates to corrective eyeglasses for persons having binocular impairment and more particularly to corrective eyeglasses in which at least one of its lenses has means for impairing or entirely blocking a portion of a wearer&#39;s field of vision. 
       BACKGROUND OF THE INVENTION 
       [0002]    Certain visual impairments such as those caused by amblyopia result in one eye being much stronger than the other. In such cases, the stronger eye generally overpowers the weaker eye and causes the weaker eye to function at less than its full potential. Over time, the binocular vision of a person who suffers from such an impairment can weaken to the point that, to all intents and purpose, the person is blind in one eye and has sight in only one eye. In other words the person has monocular vision. 
         [0003]    The purpose of the corrective eyeglasses of the subject invention is to restore or improve the vision of a person who suffers from binocular impairment. A secondary purpose of the subject eyeglasses is to encourage the weaker eye of such person to exercise while allowing his or her stronger eye to continue to function. This is to be contrasted with the time-honoured method of covering the stronger eye entirely so that the person is deprived entirely of the use of his or her stronger eye and must function with only the limited sight from the weaker eye. 
         [0004]    A third purpose of the eyeglasses of the subject invention is to exercise the muscles which control the eyes of persons who suffer from tunnel vision or other impairment of the eye. Such persons, while not visually impaired, can experience a vision that is defective in not adequately including objects away from the centre of their field of view. 
       SUMMARY OF THE INVENTION 
       [0005]    The lens of the subject corrective eyeglasses obstructs the vision of the wearer&#39;s stronger eye, either by impairing his vision or entirely blocking it. When the vision is so obstructed, the wearer&#39;s weaker eye is forced to compensate for the stronger eye&#39;s loss by taking over the area of sight not visible by the stronger eye. There are various means for obstructing the vision. One means involves the application of a coating to the lens. To this end, a coating may be applied to a portion of the lens in front of the stronger eye in order to distort or blur the object seen by the eye. Alternatively an opaque coating may be applied to a portion of the lens to entirely block the object. In both cases, the wearer is forced to use his weaker eye to see the object impaired or blocked by the coating. 
         [0006]    Another means for obstructing the wearer&#39;s vision is to form a curvature in the front and back faces of the lens in the same way as curvatures are formed in the faces of prescription lenses. Unlike prescription lenses where the curvature is intended to correct a problem in the wearer&#39;s vision, the curvature of my corrective lens is intended to obstruction the wearer&#39;s vision by impairing it or entirely blocking it. 
       DESCRIPTION OF THE DRAWINGS 
       [0007]    The corrective eyeglasses of the subject invention are described with reference to the accompanying drawings each of which shows schematically the lens in front of a wearer&#39;s stronger or dominant eye and the lens in front of his weaker eye. 
     
    
     DESCRIPTION OF PREFERRED EMBODIMENTS 
       [0008]    In  FIG. 1 , the eyeglasses have two lenses, a first  14  in front of the wearer&#39;s stronger eye  16  and a second  10  in front of the wearer&#39;s weaker eye  12 . Lens  10  is unobstructed while lens  14  has an obstructed area  18  which blocks or distorts the wearer&#39;s vision. An oblique line  20  separates the obstructed area of the lens from the remaining unobstructed area  22 . The line extends from the top  24  of the lens to the bottom  26  and is oriented such that the obstructed area is wider at the bottom than it is at the top. 
         [0009]    The obstructed area is the to left of the pupil  30  of the wearer&#39;s stronger eye when he looks straight ahead but when looks to the left, part of his vision is obstructed. The width of the obstruction, measured horizontally, is smaller above the pupil than below it so that the wearer&#39;s vision is more obstructed when he looks down than when he looks up. 
         [0010]    Since no part of the pupil is behind the obstructed area when the wearer is looking straight ahead, his forward vision is not impaired by the obstruction. Similarly when the wearer looks to the right his vision is not impaired since no part of his pupil is behind the obstruction. However when the wearer looks to the left, part of his pupil is behind the obstruction and his vision is impaired but more when he looks down than when he looks up. 
         [0011]    The term “unobstructed area” in the context of this description is intended to mean an area of transparent material such as glass or plastic which concentrates or disperses light rays. The term may accordingly refer to a prescription lens which is normally worn in the eyeglasses of the wearer. The term is also intended to cover a material which does not optically alter the light rays such as clear, undistorted glass which is used to make window panes, drinking glasses and the like. 
         [0012]    The term “obstructed area” may refer to a clear, undistorted glass which is overlaid with a coating which impairs or entirely blocks vision of the wearer of the eyeglasses. Alternatively, the term may refer to a lens which is overlaid with the same coating. Accordingly, the wearer&#39;s normal prescription lenses may become the eyeglasses of the invention where the lens through which the wearer&#39;s stronger eye sees is overlain with a coating which will impair or block the vision through that lens and where the other lens is unaltered by a coating. 
         [0013]    In summary, line  20  extends downwardly through the wearer&#39;s field of vision and that the line is oriented such that the obstructed area  18  is wider, measured horizontally, at the bottom of the lens than it is at the top. When the wearer looks straight ahead and when he looks to the right side, he looks through the unobstructed area  22  but when the wearer looks to the left he looks at the obstructed area with resulting impairment of his field of vision. The extent of impairment is least when the wearer looks upwardly to the left and greatest when the wearer looks downwardly to the left. 
         [0014]    It is believed that the obstructed area of the shape illustrated in  FIG. 1  is most advantageous for allowing maximum field of vision while promoting binocular vision. 
         [0015]    In  FIG. 2 , the eyeglasses consist of a first lens  36  in front of the stronger eye. A line  31  between the obstructed area  32  and the remainder  34  of the lens  36  consists of two segments a, b which converge toward a common point c on the same level as the wearer&#39;s pupil  38  but to the right of it so that the wearer&#39;s pupil is not covered by the obstructed area. By virtue of the shape of the line, the obstruction decreases in width above and below the eye. 
         [0016]    The obstructed area is the to right of the pupil  38  of the wearer&#39;s stronger eye when he looks straight ahead and, as such, does not obstruct the wearer&#39;s forward vision. However when the wearer looks to the right, part of his vision is obstructed. The width of the obstruction is largest horizontally to the right of the eye but diminishes in width above and below the eye. Thus the wearer&#39;s vision is more obstructed when he looks horizontally to the right than it will be when he looks up and down to the right. When he looks to the left his vision will not be impaired by the obstruction. 
         [0017]    In summary, line  31  extends downwardly through the field of vision and is oriented such that the horizontal width of the obstructed area  32  is generally the same at the bottom and the top of the lens. When the wearer looks straight ahead and when he looks to the left he looks through the unobstructed area but when the wearer looks to the right he looks at the obstructed area with resulting impairment of his field of vision. The extent of impairment is least when the wearer looks upwardly and downwardly to the right and greatest when the wearer looks horizontally to the right. 
         [0018]    In  FIG. 3  the line  40  which separates the obstructed area  42  from the remainder  44  of the first lens is vertical and again the pupil is not covered by the obstructed area. As a result when he looks straight ahead, his vision will not be obstructed. The obstructed area in the lens is the to left of the pupil of the wearer&#39;s stronger eye. When the wearer looks to the left his vision is obstructed by the same amount whether he looks up, down or horizontally to the left. 
         [0019]    In summary, line  40  is vertical and extends downwardly through the field of vision. The line is oriented such that the horizontal width of the obstructed area  42  is the same from the bottom to the top of the lens. When the wearer looks straight ahead and when he looks to the right, he looks through the unobstructed area  44  of the lens but when the wearer looks to the left, he looks at the obstructed area  42  with resulting impairment of his field of vision. The extent of the impairment is the same whether the wearer looks upwardly to the left, downwardly to the left and horizontally to the left. 
         [0020]    The first lens  50  of  FIG. 4  is similar to that of lens  36  of  FIG. 2  except that the obstructed area  52  is much larger than that of lens  36 . In  FIG. 4 , the line  54  between the obstructed area  52  and the remainder  56  of the lens consists of two segments e, f which converge toward a common point g on the same level as the wearer&#39;s pupil. 
         [0021]    The obstructed area  52  is to the right of the pupil of the wearer&#39;s stronger eye when he looks straight ahead and does not obstruct his vision. However when the wearer looks to the right, most of his vision is obstructed. The horizontal width of the obstruction is least horizontally to the right of the eye but increases in width above and below the eye. Thus the wearer&#39;s vision is less obstructed horizontally to the right than it is when he looks up and down to the right. When he looks to the left his vision is not impaired. 
         [0022]    In summary, line  54  extends downwardly through the field of vision and is oriented such that the width, measured horizontally, of the obstructed area  52  is generally the same at the bottom and the top of the lens. When the wearer looks straight ahead and when he looks to left, he looks through the unobstructed area  56  but when the wearer looks to right he looks at the obstructed area with resulting impairment of his field of vision. The extent of impairment is greatest when the wearer looks upwardly and downwardly to the right and least when the wearer looks horizontally in the same direction. 
         [0023]    In  FIG. 5  the line  60  between the obstructed area  62  and the remainder  64  of the lens is diagonal as is the line  70  between the obstructed area  72  and the remainder  74  of the lens in  FIG. 6 . In the former Figure, the obstructed area  62  is in the upper area of the lens while in the latter Figure, the obstructed area  72  is in the lower area. 
         [0024]    In  FIG. 5 , the obstructed area is above and to the left of the of the wearer&#39;s stronger eye when he looks straight ahead and does not obstruct his forward vision. However when he looks vertically above or when he looks horizontally to the left or when he looks above and to the left, his vision is obstructed. His vision is less obstructed when he looks down and to the left than it is when he looks horizontally to the left, or when he looks upward and to the left or when he looks vertically straight up. 
         [0025]    In  FIG. 6 , the obstructed area is below and to the right of the wearer&#39;s eye. The wearer&#39;s vision is less obstructed when he looks up and to the right than it is when he looks down and in the same direction. 
         [0026]    In  FIG. 7  the line  80  which separates the obstructed area  82  from the remainder  84  of the lens is curved as is the line  86  which separates the obstructed area  90  from the remainder  88  of the lens illustrated in  FIG. 8 . In both lenses, the obstructed areas are elsewhere than in front of the wearer&#39;s pupil. 
         [0027]    In the lens of  FIG. 7 , the wearer&#39;s vision through his stronger eye is obstructed if he looks to the left and is partially obstructed if he looks straight up or down. In the lens of  FIG. 8 , the wearer&#39;s vision through his stronger eye is obstructed if he looks to the right, whether horizontally or up or down, but is not be impaired if he looks straight up or down or to the left. 
         [0028]    In summary, in  FIG. 7 , line  80  extends downwardly through the field of vision and is oriented such that the width, measured horizontally, of the obstructed areas  82  at the bottom and top of the lens is equal. When the wearer looks straight ahead and when he looks to right, he looks through the unobstructed area  84  but when the wearer looks to the left, he looks at the obstructed area  82  with resulting impairment of his field of vision. The extent of impairment is greatest when the wearer looks downwardly and upwardly to the left and least when the wearer looks horizontally to the same side. 
         [0029]    In  FIG. 8  line  86 , like line  80  of  FIG. 7 , extends downwardly through the field of vision and is oriented such that the obstructed areas at the bottom and top of said lens are equal and such that when the wearer looks straight ahead and when he looks to the left he looks through the unobstructed area  88  but when he looks to the right he looks at the obstructed area  90  with resulting impairment of his field of vision. The extent of impairment is least when he looks downwardly and upwardly to the right and greatest when he looks horizontally in the same direction. 
         [0030]    The lenses in the Figures show both straight and curved lines oriented at various angles that separate the obstructed areas from the remainder of the lenses. The Figures are illustrative of the various shapes and orientations of the line and are not intended to limit the lines to any particular shape or orientation. 
         [0031]    The lenses of the subject invention may have a single focus, a double focus i.e. a bifocal or a triple focus i.e. a trifocal. 
         [0032]    It will be understood, of course, that modifications can be made in the eyeglasses of the subject invention without departing from the scope and purview of the invention as defined in the appended claims.