Abstract:
An apparatus is provided for finding and defining a prescription for prism glasses for Diplopic patients and AMD patients whose Macula and Fovea are damaged enough that the patients have double vision, but, still have relatively good acuity. The apparatus positions lenses in infinitely variable locations horizontally and vertically in front of the patient&#39;s eyes until the patient indicates that he/she sees the two images fuse. The H-V coordinates of the location of the Optic center of each lens axis in relation to the patient&#39;s visual axis are decentration dimensions indicated for each eye by the H and V dials on the apparatus and are thus the basis for an accurate prescription for prism lenses.

Description:
CROSS REFERENCE TO RELATED NON-PROVISIONAL APPLICATION 
     This Continuation-In-Part (CIP) application claims the benefit of the filing date of U.S. Non-Provisional patent application Ser. No. 12/854,373 filed on Aug. 11, 2010 and titled “Apparatus for Determining Prescription for Reading Lenses for Eyes with Mild AMD”, which is hereby incorporated in this CIP. 
     LEXICON 
     Generally, equations and terminology familiar to Opticians are used throughout these Specifications. 
     Lens-blank means a round, polished lens that is edged to fit the lens-holders of the preferred embodiment. 
     Lens-set means two (OD and OS) lenses of each diopter power specified and plus and/or minus diopter specified. 
     Integral applied to components of the preferred embodiment, means that a component, that is said to be integral to a larger component, already named and defined, is cast with the said named component as a single homogeneous piece that can not be separated into individual parts. 
    
    
     BACKGROUND 
     Many people suffering from Adult-onset Macular Degeneration (AMD) have damage to the Macula that has repositioned the Fovea (center of the Macula) causing a new visual-axis to be slightly offset from the original (normal) visual-axis. This is very common in older people. The result, in many cases, is Diplopia. Double vision occurs when the image that one eye sees does not coincide with the image that the other eye sees when looking with both eyes at the same time at the same physical object, making it appear that there are two of everything in the field of view of the Macula and Fovea. The brain can accommodate for slight differences, but, when the offset becomes too great for the brain to accommodate-double vision results. Peripheral vision is not affected by AMD. 
     Many AMD patients still have relatively good acuity in the AMD eye but the offset of the visual-axis still results in double vision. For patients with AMD in both eyes, the result most likely will be double vision. Another cause of double vision is Strabismus of which there are several types and which sometimes is a result of the right and left eye muscles&#39; inability to coordinate to focus in on an object and make the two images fuse. Double vision sufferers have to find their own method of coping with the problem. For some people, surgery is the answer. For the other people, one way to cope is to close one eye while viewing. This quickly becomes tiring. Another method is to wear an eye-patch instead of closing the eye. The eye-patch interferes with eyeglasses making that option also unsatisfactory. A problem with both methods is that the person loses the peripheral vision in that eye. Losing peripheral vision can actually be dangerous if the person is in a dangerous industrial setting, or driving a vehicle where it is important to see danger approaching with the periphery of one&#39;s vision. One crude method of addressing the problem has been the use of Prism Bars held in front of one eye by Ophthalmologists to guess at the amount of induced prism required in eyeglass lenses by the patient to bring the two images together as one. That method is not accurate and has been the source of much dissatisfaction on the part of patients as well as the Ophthalmologists. There are also hand held rotary prisms available. Here again hand held means not very accurate. 
     Thus, there has always been a need for a more accurate and satisfactory way of improving the seeing ability of such individuals. 
     SUMMARY 
     I have had AMD for a number of years and relied on the methods mentioned in the BACKGROUND above and found them to be very unsatisfactory. I was constantly on the lookout for a way that was better. I noticed one day, while using a magnifying glass, that as the magnifying glass is moved across a page in one direction that the words on the printed page appeared to move in the opposite direction. Well, that was not news to me. What was new was me thinking that there may be a new way to use the prism effect. So I theorized that if my reading glasses lens were relocated within their frames, let&#39;s say move one up and out (away from the nose) and the other one down and out in infinitely variable distances and combinations, that at some point an image of an object would focus on the center of each Fovea of my two eyes. In other words, the images might be relocated just the exact distance and direction to fuse and appear to me as one image (single vision) instead of two images (double vision) for each object viewed. Through experimentation I found my theory to be correct. As a matter of fact, it worked even better than I had hoped. So, it became obvious to me that there was a need for an apparatus that could quickly and accurately determine what those distances and directions are for any Diplopic patient. Those distances and directions plus the diopter strengths (and other requirements of the eye) would then be the prescription for eyeglass lenses for a Diplopic patient. Hereinafter those distances and directions are referred to as “offset distances (H-V coordinates)”. Ideally the apparatus should be infinitely variable within its limits, and would split the induced prism equally but oppositely between the two lenses, to provide maximum accuracy and comfort. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a side orthographic view of a normal eye (Emsley Standard Reduced 60-diopter eye), except for farsightedness, viewing an object through a magnifying lens. 
         FIG. 2  is a side orthographic view of an eye (Emsley Standard Reduced 60-diopter eye) with farsightedness and AMD, viewing an object through a magnifying lens. 
         FIG. 3  is a graphic representation of how a standard Amsler Grid looks to a pair of normal eyes. It also represents how a standard Amsler Grid looks to a pair of eyes, one or both of which have mild AMD, but are viewing through corrective lenses embodying the principles of the present invention. 
         FIG. 4  is a graphic representation of how a standard Amsler Grid might look to an eye with mild AMD where the Fovea (center of the Macula) has shifted slightly downward creating a new visual-axis slightly offset from the original normal visual-axis. 
         FIG. 5  is a graphic representation of how the alphabetical character “A” might look to a person with Strabismus or with mild AMD in one or both eyes viewing with both eyes through ordinary reading lenses. 
         FIG. 6  is a graphic representation of how the alphabetical character “A” will look to a person with normal vision viewing with both eyes. It also represents how the alphabetical character “A” might look to a pair of eyes with Strabismus or in which one or both of them has mild AMD but are viewing through corrective lenses embodying the principles of the present invention. 
         FIG. 7  is an orthographic front view of the preferred embodiment employing the principles of the present invention. 
         FIG. 8  is an enlarged partial front view of the preferred embodiment employing the principles of the present invention. 
         FIG. 9  is an orthographic side view of the preferred embodiment employing the principles of the present invention. 
         FIG. 10  is a partial orthographic back view of the preferred embodiment employing the principles of the present invention. 
         FIG. 11  is an orthographic bottom view of the preferred embodiment employing the principles of the present invention. 
         FIG. 12  is a section taken horizontally through  FIG. 7 , looking up. 
         FIG. 13  is a partial side view taken from  FIG. 9 . 
         FIG. 14  illustrates how the decentration (H-V coordinates) obtained from an examination of a Diplopic patient&#39;s eyes, using the preferred embodiment employing the principles of the present invention, become the Rx and then are translated into the actual orientation of each respective lens-axis in relation to the patient&#39;s visual-axis. 
         FIG. 15  illustrates a forehead-rest that steadies the embodiment in relation to the patient&#39;s eyes. It is attached to the patient&#39;s side of the embodiment with adhesive to a transparent gear-cover. 
         FIG. 16  illustrates an adjustable eyeglass frame (Front View, Side View and partial enlarged view) for holding stationary lenses for patients who require a negative (−) lens in addition to a prism lens to obtain the necessary magnification for the intended purpose 
         FIG. 17  is an enlarged view of the OD lens holder showing, in detail, the radial scale divided into two degree increments. 
         FIG. 18  is an enlarged view of the OS lens holder showing, in detail, the radial scale divided into two degree increments. 
         FIG. 19  is a Table titled HOW TO SELECT LENSES FOR THE PREFERRED EMBODIMENT/PATIENT with notes A through C and  1  through  7  which explain the use of the Table. 
     
    
    
     DETAILED DESCRIPTION 
     All references to “right” and “left” in these Specifications and Claims are relative to the patient&#39;s perspective while viewing through a right lens  29  and a left lens  30  shown in  FIG. 7 , the front view of the preferred embodiment, also further clarified by the graphic of a patient&#39;s-eye  74  shown in  FIG. 9 , a side view. 
     Like referenced elements are represented by like reference numbers throughout the drawings. Referenced components shown in a particular Figure but not described therein under that Figure&#39;s heading is because the referenced component has already been described in detail in a discussion of a previous Figure. 
       FIG. 1  is a side orthographic view of a normal eye (Emsley Standard Reduced 60-diopter eye) hereinafter referred to as ESR60-DE  2 A, and it is assumed that it is normal except for farsightedness. Here it is shown viewing an object  7  through a first-magnifying-lens  6 A the diopter strength of which has been determined by a conventional eye exam. A first-image  8 A of the object  7  is formed upside down on a first-Fovea  4 A and surrounding first-Macula  5 A (size exaggerated for clarity). Surrounding the first-Macula  5 A is a first-Retina  11 A. For the purpose of illustrating how the first-image  8 A is formed, light rays emanating from the object  7 , and a first-magnifying-lens-axis  3 A, and a first-visual-axis  1 A are also shown. 
       FIG. 2  is an orthographic side view of an eye (Emsley Standard Reduced 60-diopter eye) hereinafter referred to as AMD-ESR60-DE  2 B, and it is assumed that in addition to farsightedness it is affected by AMD. Here it is shown viewing the object  7  through a second-magnifying-lens  6 B. In this view the effects of AMD has shifted a second-Fovea  4 B downward a small second-distance  10 . A second-magnifying-lens-axis  3 B of the second-magnifying-lens  6 B is shifted upward an exact first-distance  9  required to cause a second-image  8 B to form on the center of the second-Fovea  4 B and (if large enough), on a second-Macula  5 B which will make the object  7  appear to be in the same location in space as the normal eye (without AMD) sees it. Surrounding the second-Macula  5 B is a second-Retina  11 B. Thus with both eyes focusing on the object  7  the two images fuse. 
     If the second-magnifying-lens-axis  3 B were to be aligned with a second-visual-axis  1 B, that existed prior to the onset of AMD, then with both eyes open, the patient would see two separate objects  7  (one above the other). This is the case because the image formed in AMD-ESR60-DE  2 B would not be centered on the second-Fovea  4 B as it is in ESR60-DE  2 A, thus the patient would see two objects  7  that do not fuse (coincide). 
     Where a negative diopter lens is required for the patients eye, the image will be shifted in a direction that is opposite to the direction of a positive diopter lens. 
       FIG. 3  is a graphic representation of how a standard Amsler Grid looks to a pair of normal eyes. It also represents how a standard Amsler Grid looks to a pair of eyes in which one or both of them has mild AMD but are viewing through prism lenses embodying the principles of the present invention. The Amsler Grid may appear slightly blurry due to mild loss of acuity caused by AMD, but the lines will appear straight. Prism lenses inherently introduce slight blurring caused by dispersion. 
       FIG. 4  is a graphic representation of how the standard Amsler Grid might look to an eye with mild AMD, such as AMD-ESR60-DE  2 B, viewing through an ordinary magnifying lens, where the Fovea  4 B (center of the Macula) has shifted downward the small second-distance  10  away from the normal second-visual-axis  1 B. 
       FIG. 5  is a graphic representation of how the alphabetical character “A” might look to a person viewing it with both eyes where one eye has a mild case of AMD such as AMD-ESR60-DE  2 B, in which the Fovea  4 B has shifted slightly downward away from the normal visual-axis  1 B. The other eye could be normal such as ESR60-DE  2 A or it could have mild AMD like AMD-ESR60-DE  2 B but with the offset in a different direction and/or a different distance. A tiny shift is accommodated for by the brain which makes the viewer see only one “A”, but eventually as the distortion becomes greater and greater, the brain can no longer accommodate so that the viewer then sees double. In this case, one “A” above another. 
       FIG. 6  is a graphic representation of how the alphabetical character “A” will look to a person with normal vision in both eyes. The images formed on the first-Fovea  4 A and the first-Macula  5 A of the two eyes fuse and appear to the viewer as one object. It also represents how the alphabetical character “A” might look to a pair of eyes in which one or both of them has mild AMD but are viewing through prism lenses made using the principles of the present invention. The image may appear slightly blurry due to mild loss of acuity due to AMD and blurring due to dispersion. 
     Although the present inventor was able to make a pair of reading glasses by trial and error by using the principles of the present invention and the scientific principles described in  FIG. 1  and  FIG. 2 , there needed to be an apparatus employing the principles of the present invention that would provide a quicker and more accurate way to find and define a prescription (Rx) for prism lenses. The present inventor did conceive such an apparatus and it is the “preferred embodiment” shown in the Drawings,  FIG. 7  through  FIG. 13  and  FIG. 15  through  FIG. 18 . Plain spherical lenses with a diopter strength appropriate for a patient could be positioned in lens holders in front of the patient&#39;s eyes by an apparatus having an infinitely variable graduated horizontal control that moves the pair of lens holders slowly in front of the patients eyes equal distances but in opposite directions and, independently from the horizontal control, an infinitely variable graduated vertical control could slowly move the lens holders in front of the patients eyes equal distances but in opposite directions. The horizontal control could be operated until the patient sees two vertical lines fuse, then the vertical control could be operated until the patient sees two horizontal lines fuse-induced prism by decentration. The numbers on the controls would then be the basis for a prism Rx for the patient. The preferred embodiment described herein satisfies all of those criteria. 
       FIG. 7  and  FIG. 8  illustrate the front view and a partial enlarged front view respectively of the preferred embodiment, employing the principles of the present invention. Components pertinent to the discussion of  FIG. 7  and  FIG. 8  but that are more clearly shown in other Figures are so noted. The front view clearly shows linkages between a horizontal-adjustment-knob  50  (a first human interface) and a user selectable right-lens-blank  29 . Likewise linkages between the horizontal-adjustment-knob  50  and a user selectable left-lens-blank  30  are shown. A vertical-adjustment-knob  49  (a second human interface) is shown linked to the right-lens-blank  29 . Likewise linkages between the vertical-adjustment-knob  49  and the left-lens-blank  30  are shown. These linkages provide the basic motions necessary for the lenses, but, more detail is provided below for greater clarity. 
     Horizontal Control: Horizontal movement of the right-lens-blank  29  begins with the horizontal-adjustment-knob  50  that has a first-central-hole  89  ( FIG. 13 ) along its axis sized to accept a horizontal-pinion-axle  56  that passes through the first-central-hole  89  ( FIG. 13 ) and is prevented from rotating within the horizontal-adjustment-knob  50  by a first-setscrew  84 . Further, the horizontal-pinion-axle  56  passes through a slip-fit-hole  76  ( FIG. 13 ) in a bearing-plate  86  and through a horizontal-pinion  70  ( FIG. 13 ) and finally terminates in a bearing-hole  88  ( FIG. 13 ) in a horizontal-guide  31 . The bearing-plate  86  is held in place with four bearing-plate-fasteners  87 . A locknut  72  ( FIG. 13 ) on the horizontal-pinion-axle  56  confines the horizontal-pinion  70  ( FIG. 13 ) to it&#39;s required position on the horizontal-pinion-axle  56 . The portion of the horizontal-pinion-axle  56  that fits within the horizontal-pinion  70  ( FIG. 13 ) is non-round in cross section matching a non-round-hole  91  ( FIG. 13 ) in the center of the horizontal-pinion  70  ( FIG. 13 ) whereby any rotation of the horizontal-adjustment-knob  50  results in an equal rotation of the horizontal-pinion  70  ( FIG. 13 ). 
     The horizontal-guide  31  has a bottom-horizontal-T-shaped groove  80  ( FIG. 13 ) and a top-horizontal-T-shaped-groove  81  ( FIG. 13 ) running parallel to each other and spaced apart far enough to accommodate a bottom-horizontal-rack  33  and a top-horizontal-rack  34 , each respective rack has a T-shaped cross section that matches and engages the T-shaped grooves in the horizontal-guide  31  wherein the horizontal-pinion  70  ( FIG. 13 ) is juxtaposed between and engages both the bottom-horizontal-rack  33  and the top-horizontal-rack  34  causing them to slide equal distances but in opposite directions when the horizontal-adjustment-knob  50  is rotated. 
     A right-vertical-rod  37  is fixedly attached to a right end of the bottom-horizontal-rack  33  through the use of a vertical-rod-fastener  57  and two right-lateral-stability-pins  77  integral to the right-vertical-rod  37  and the right-vertical-rod  37  is vertically slidably connected to a right-vertical-rod-bushing  60  which is integral to a right-lens holder  62  so that the right-lens-holder  62  is free to slide vertically along the length of the right-vertical-rod  37  when it is propelled to do so by a right-horizontal-rod  39 , but its horizontal movement is restrained by the right-vertical-rod  37 . The end result of the foregoing detailed linkages is that horizontal motion of the bottom-horizontal-rack  33  imparts an equal motion to the right-lens-holder  62 . 
     A left-vertical-rod  38  is fixedly attached to a left end of the top-horizontal-rack  34  through the use of the vertical-rod-fastener  57  and two left-lateral-stability-pins  78  integral to the left-vertical-rod  38  and the left-vertical-rod  38  is vertically slidably connected to a left-vertical-rod-bushing  61  which is integral to a left-lens holder  63  so that the left-lens-holder  63  is free to slide vertically along the length of the left-vertical-rod  38  when it is propelled to do so by a left-horizontal rod  40 , but its horizontal movement is restrained by the left-vertical-rod  38 . The end result of the foregoing detailed linkages is that horizontal motion of the top-horizontal-rack  34  imparts an equal motion to the left-lens-holder  63 . 
     Vertical Control: Vertical movement of the right-lens-blank  29  begins with the vertical-adjustment-knob  49  that has a second-central-hole  90  ( FIG. 12 ) along its axis sized to accept a vertical-pinion-axle  55  that passes through the second-central-hole  90  and is prevented from rotating within the vertical-adjustment-knob  49  by a second-setscrew  85 . Further, the vertical-pinion-axle  55  passes through a second-slip-fit-hole  93  ( FIG. 12 ) in a vertical guide  32  and through a vertical-pinion  71  ( FIG. 12 ). The locknut  72  ( FIG. 12 ) on the vertical-pinion-axle  55  confines the vertical-pinion  71  ( FIG. 12 ) to its required position on the vertical-pinion-axle  55 . The portion of the vertical-pinion-axle  55  that fits within the vertical-pinion  71  ( FIG. 12 ) is non-round in cross section matching a non-round-hole  92  ( FIG. 12 ) in the center of the vertical-pinion  71  ( FIG. 12 ) whereby any rotation of the vertical-adjustment-knob  49  results in an equal rotation of the vertical-pinion  71  ( FIG. 12 ). 
     The vertical-guide  32  has a right-vertical-T-shaped-groove  82  ( FIG. 12 ) and a left-vertical-T-shaped-groove  83  ( FIG. 12 ) running parallel to each other and spaced apart far enough to accommodate a right-vertical-rack  35  and a left-vertical-rack  36 , each respective rack has a T-shaped cross section that matches and engages the T-shaped grooves in the vertical-guide  32  wherein the vertical-pinion  71  ( FIG. 12 ) is juxtaposed between and engages both the right-vertical-rack  35  and the left-vertical-rack  36  causing them to slide equal distances but in opposite directions when the vertical-adjustment-knob  49  is rotated. 
     The right-horizontal-rod  39  is tightly threaded into a bottom end of the right-vertical-rack  35  and the right-horizontal-rod  39  is horizontally slidably connected to a right-horizontal-rod-bushing  58  which is integral to the right-lens-holder  62  so that the right-lens-holder  62  is free to slide horizontally along the length of the right-horizontal-rod  39  when it is propelled to do so by the right-vertical-rod  37 , but its vertical movement is restrained by the right-horizontal-rod  39 . The end result of the foregoing detailed linkages is that vertical motion of the right-vertical-rack  35  imparts an equal motion to the right-lens-holder  62 . 
     The left-horizontal-rod  40  is tightly threaded into a bottom end of the left-vertical-rack  36  and the left-horizontal-rod  40  is horizontally slidably connected to a left-horizontal-rod-bushing  59  which is integral to the left-lens-holder  63  so that the left-lens-holder  63  is free to slide horizontally along the length of the left-horizontal-rod  40  when it is propelled to do so by the left-vertical-rod  38 , but its vertical movement is restrained by the left-horizontal-rod  40 . The end result of the foregoing detailed linkages is that vertical motion of the left-vertical-rack  36  imparts an equal motion to the left-lens-holder  63 . 
     Crosshairs and Lens-holders: The user selectable right-lens-blank  29  is forced into a groove in the right-lens-holder  62  and is held in place by tension due to the right-lens-holder  62  having a slightly smaller diameter than the right-lens-blank  29  by an amount sufficient to prevent the right-lens-blank  29  from falling out; likewise for the left-lens-blank  30  and the left-lens-holder  63 . 
     Zeroing: It is important to provide a pair of plano lenses with crosshairs thereon in the set of lenses that are provided for use in conjunction with the preferred embodiment. A zeroing thumbscrew  46  ( FIG. 8 ) is loosened. With the lenses in place the right-lens-blank  29  and the left-lens-blank  30  can be accurately centered on the patient&#39;s eyes. This is done by adjusting a spacing of the pair of crosshairs by rotating the horizontal-adjustment-knob  50  until the spacing of the pair of crosshairs matches a spacing of the patient&#39;s P.D. 
     At this point (after aligning crosshairs with eyes) a rotatable circular horizontal-scale  48  ( FIG. 8 ) is rotated until zero on the scale aligns with a single horizontal-index  52  printed on the horizontal-adjustment-knob  50  and the zeroing-thumbscrew  46  is tightened thereby clamping the horizontal-scale  48  between a washer  54  and the bearing-plate  86 . This is called “zeroing” the scale and splits the horizontal “offset” distance (determined during an examination of a patient) equally but oppositely between the right and left lenses.  FIG. 14  provides more detail regarding offset (decentration). 
     Lens Sets: Lens sets for use in conjunction with the lens-holders  62  and  63  of the Preferred Embodiment generally include the most popular centered-lens diopters in both plus and minus powers. These lenses  29  and  30  are edged to fit the lens holders  62  and  63  and have a segment removed from them to prevent interference when the two lenses are moved toward each other. In that position (centers of the lenses closer than the patient&#39;s P.D.), the two flat parts of the lenses face each other allowing the centers of the lenses to be closer together without interference. If the patient&#39;s eyes are such that the centers of the lenses must be located farther apart than the patient&#39;s P.D., the flat parts of the lenses are rotated away from each other so that there will be more viewable lens area available. Decentered lens sets are also provided for use in conjunction with the lens-holders  62  and  63  of the Preferred Embodiment and generally include the most popular Diopters in both plus and minus powers for each of at least three sub-sets of decentered lenses of varying degrees of decentration up to and a maximum of 70 mm of decentration. These lenses  29  and  30  are edged to fit the lens holders  62  and  63 . Lens sets for use in conjunction with the lens-holders  99  of the Preferred Embodiment generally include the most popular centered lens diopters in minus powers. These lenses  98  are smaller than the lenses  29  and  30 . 
     User Instructions: The horizontal-scale  48  and the vertical-scale  47  are both circular scales with millimeter indications ranging from zero to fifteen on each side of a zero. On both scales the right side numerals and indexes are red and on the left side are blue. This is a color code for use with a user-instructions  44  that clearly indicates whether a number on the horizontal-scale  48  aligned with the horizontal-index  52  is indicating a distance that is BI or BO for the patient&#39;s OD and BI or BO for the patient&#39;s OS. Likewise for a number aligned with the vertical-index  51 , the color code in the instructions  44  indicates whether the distance is BU or BD for the patient&#39;s OD and BU or BD for the patient&#39;s OS. 
     Interfacing with an articulated arm: A top extension of the vertical-guide  32  is formed to accept a fitting on a commercially available articulated-arm  79  ( FIG. 7 ) that can be used for positioning the preferred embodiment in front of the patient&#39;s eyes. See  FIG. 9  for a description of four front-lugs  41  and four lug-fasteners  43 . 
       FIG. 9  illustrates the side view of the preferred embodiment, employing the principles of the present invention. A transparent-gear-cover  73 , and transparent-gear-cover-fasteners  75  are described under  FIG. 10 . A human eye  74  is self explanatory. This is the best view in which to discuss the means for securely fastening the horizontal-guide  31  to the vertical-guide  32 . Four front-lugs  41  are provided integral to the horizontal-guide  31  flush with the back side of the horizontal-guide  31 . These lugs align with four back-lugs  42  provided integral to the vertical-guide  32  which are flush with the front side of the vertical-guide  32 . All four pairs of lugs are fastened together with sufficient structural integrity with four sets of bolt and nut lug-fasteners  43 . A forehead-rest  96  ( FIG. 15 ) is shown broken away. A full view of it is shown in  FIG. 15 . Refer to  FIG. 7  and  FIG. 8  for a description of other referenced components. 
       FIG. 10  is an orthographic back view of the preferred embodiment. This shows the gear teeth of the vertical-pinion  71  engaging both the right-vertical-rack  35  and the left-vertical-rack  36  gear teeth. It is so open and accessible that a transparent-gear-cover  73  (invisible in this view) is provided to prevent a patient&#39;s hair from getting tangled in the gears. The transparent-gear-cover  73  has a height and width matching the vertical-guide  32  and is secured in place with fasteners  75 . The forehead-rest  96  is not shown so that the relationship between the pinion  71  and the two racks  35  and  36  can be clearly shown. The horizontal-guide  31  is shown behind the vertical-guide  32 . The vertical-pinion  71  is shown held in place on the vertical pinion-axle  55  by the locknut  72 . 
       FIG. 11  illustrates the bottom view of the preferred embodiment, employing the principles of the present invention. Refer to  FIG. 7  and  FIG. 8  for a complete description of the components referenced, except the forehead-rest  96  is not referenced in  FIG. 7  and  FIG. 8 . See  FIG. 15  for a complete description of the forehead-rest  96 . 
       FIG. 12  Illustrates a partial section view taken through  FIG. 7 . Components of particular interest in this view are the right-vertical-T-shaped-groove  82  and the left-vertical-T-shaped-groove  83  in which the right-vertical-rack  35  and the left-vertical-rack  36  respectively slide up and down in the vertical-guide  32  in opposite directions as the vertical-adjustment-knob  49  is rotated clockwise and counterclockwise. Due to the connection of the vertical-adjustment-knob  49  to the vertical-pinion  71  through the vertical-pinion-axle  55 , the rotational movement of the vertical-pinion  71  mimics the rotation of the vertical-adjustment-knob  49 . The vertical-pinion-axle  55  passes through the second-central-hole  90 , the second-slip-fit-hole  93  and the second-non-round-hole  92  in the vertical-pinion  71 . The vertical-pinion  71  is held in its proper place by the locknut  72 . 
       FIG. 13  illustrates a partial side view taken from  FIG. 9 . Components of particular interest in this partial view are the ones interconnecting the horizontal-adjustment-knob  50  with the sliding movement of the bottom-horizontal-rack  33  and the top-horizontal-rack  34  within the bottom-horizontal-T-shaped-groove  80  and the top-horizontal-T-shaped groove  81 , both within the horizontal-guide  31 . The horizontal-pinion-axle  56  passes through the first-central-hole  89  in the center of the horizontal-adjustment-knob  50  and is prevented from rotating within the first-central-hole  89  by the first-set-screw  84  (hidden in this view). The horizontal-pinion-axle  56  continues on through the first-slip-fit-hole  76  in the bearing-plate  86  and on through the first-non-round-hole  91  in the horizontal-pinion  70  and terminating in the bearing-hole  88 . The locknut  72  holds the horizontal-pinion  70  in its proper place. Refer to  FIG. 7  and  FIG. 8  for a complete description of other components referenced. 
       FIG. 14  illustrates how a right-lens-blank-axis  21  of a right-lens-blank  16  is above a right-frame-visual-axis  14  by a right-vertical-distance  25  as determined by an eye exam employing the principles of the present invention; the right-lens-blank-axis  21  is to the left of the right-frame-visual-axis  14  by a right-horizontal-distance  27  as determined by the same eye exam. 
     Likewise  FIG. 14  illustrates how a left-lens-blank-axis  22  of a left-lens-blank  17  is below a left-frame-visual-axis  15  by a left-vertical-distance  26  and the left-lens-blank-axis  22  is to the right of the left-frame-visual-axis  15  by a left-horizontal-distance  28  as determined by the same eye exam. 
     It can now be seen that with this prescription, a commercially available edging machine can be used to grind the right-lens-blank  16  to fit a right-lens-cut-line  20  and the left-lens-blank  17  to fit a left-lens-cut-line  19  so both lenses can be mounted in eyeglass-frames  18  for use by a Diplopic patient for improved reading ability. 
       FIG. 15  illustrates the forehead-rest  96  that steadies the embodiment in relation to the patient&#39;s eyes  74 . It is attached with adhesive to the transparent gear-cover  73  (hidden by the left-vertical-rod  38 ). The forehead-rest  96  is positioned and fixedly attached to the patient side of the apparatus to press against the patient&#39;s forehead when the eyes align with the centers of a pair of plano lenses having crosshairs wherein the forehead-rest  96  is constructed of a soft spongy material covered with soft vinyl. 
       FIG. 16  illustrates a rigid adjustable eyeglass frame (Front View, Side View and partial enlarged view) for holding stationary-lenses  98  for patients who require a negative (−) lens in addition to a prism lens to obtain the necessary magnification for the intended purpose. The eyeglass-frame  105  has on each end a PD-millimeter-scale  104  ranging from approximately 25 mm to 35 mm to accommodate most PDs. A rigid integral central-extension  106  extends upward to the level of a horizontal-slot  97  at which point a rigid integral horizontal-fitting  107  is sized to snuggly fit into the horizontal-slot  97  located near the bottom of the Vertical-guide  32  (doctor&#39;s side). The lens  98  is held in front of the patient&#39;s eye by a lens-holder  99  that has a groove that snuggly fits the lens with sufficient tension to prevent the lens falling out. Integral to the lens-holder  99  is a rigid extension  100  that projects outward away from the patient and then vertically to an integral sleeve  102  that freely slides along the eyeglass-frame  105 , when a thumbscrew  108  is loose. The sleeve  102  has a window  101  on the doctor&#39;s side that allows full view of a sufficient portion of the PDmillimeter-scale  104 . The sleeve  102  has a PD-index  103  at the bottom edge of the eyeglass-frame  105  for the purpose of aligning the PD index  103  with the appropriate PD on the PD-milllimeter-scale at which time the thumbscrew  108  is tightened. 
       FIG. 17  is an enlarged view of the OD lens holder showing, in detail, the radial scale divided into two degree increments. A simple eye test can reveal the “angle” of the displacement of images seen by a Diplopic patient. The angle for the OS will be 180 degrees from the OD angle. This allows the doctor to insert a decentered lens into the lens-holder  62  and rotate it until the black index is aligned with the angle found (black number) by the eye test. If no such black angle exists on the OD-scale  109  then rotate the lens until the green index on the lens aligns with the angle that is identified with green numbers. Mathematically add the H &amp; V components (based on the angle) of the decentered lens to the H &amp; V components found by the horizontal-scale  48  and vertical-scale  47  according to the User-instructions  44  printed on the vertical-guide  32  after the Rx has been fine tuned using the horizontal-adjustment-knob  50  and vertical-adjustment-knob  49  controls. With these combined H &amp; V values an Rx can be calculated and written in whatever notation is desired for the OD. Ultimately the OS will have values equal to but opposite the H &amp; V values of the OD. 
       FIG. 18  is an enlarged view of the OS lens holder showing, in detail, the radial scale divided into two degree increments. Based on information already known (from  FIG. 17  above) the doctor can insert a decentered lens into the lens-holder  63  and rotate it until the black index is aligned with the angle found (black number) by the eye test. If no such black angle exists on the OS-scale  110  then rotate the lens until the green index on the lens aligns with the angle that is identified with green numbers. Mathematically add the H &amp; V components (based on the angle) of the decentered lens to the H &amp; V components found by the horizontal-scale  48  and vertical-scale  47  according to the User-instructions  44  printed on the vertical-guide  32  after the Rx has been fine tuned using the horizontal-adjustment-knob  50  and vertical-adjustment-knob  49  controls. With these combined H &amp; V values an Rx can be calculated and written in whatever notation is desired for the OS. 
     The foregoing merely illustrates the principles of the invention. For example, although the means for positioning the lens in front of the patient&#39;s eyes in the illustrated embodiment are rack and pinion gears, other means are possible such as threaded screws or servo motors. The millimeter scales could be a different unit. The circular scales and the indexes on round knobs could be changed to linear scales affixed to the racks with single indexes affixed to the vertical guide and the horizontal guide. The sliding fit of the four rod bushings could be replaced with linear-ball bearings. 
     It will thus be appreciated that those skilled in the art will be able to devise numerous alternative arrangements that, while not shown or described herein, employ the principles of the invention and thus are within its spirit and scope.