Патент USA US2118132код для вставки
May 24, 1938. AAMS, JR, ET AL ~ ' y 2,118,132 l CORRECTING OCULAR DEFECTS y Filed oct. 2e, 19:54 l 4'sneets-sne'et 2r CoA/CA VE ) ¿fili ,B L25 www 5a ZA /A /K CONVEX 6 .9 /0// /2 COA/CAVE kw [2H/098765432!0/23456789/0/l/2 ¿je N, „222W Y ` May 24, 1938. v ' A. Amas, JR.. Er AL CORRECTING OCULAR DEFECTS Filed oct. ze, 1954 2,118,132 I ` 4 sheets-sheet s ì May 24, 1938. A. AMES, JR., El' AL 2,118,132 CORRECTING OCULAR DEFECTS w Filed OCT.. 26, 1934 im w' Y»v 4 Sheets-Sheet 4 2,118,132 Patented May 24, 193s . PATENT: oFFIcE UNITED STATES 2,118,132 ` . CORRECTmG OCULAR'DEFECTS Adelbert Ames, Jr.,’Gordon H. Gliddomand Ken \ l f Ogle, Hanover, N. H., assignors to Trustees of Dartmouth College, Hanover, N. H., a corporation of New Hampshire neth N. Application ‘October 26, 1934, Serial No. 750,162 ’ v y12 claims. (ci. fis-54) Heretofore, various defects ofthe eyes have been known and corrected in different ways ap propriate to these defects. For example, dioptric errors have been corrected by spherical, cylin 5 drical or torio lenses, and muscular defects or phorias by means- of prism lenses which affect the vergence of the eyes by changing the direc~ tion of the line of sight of an eyeball when the ocular muscles fail to turn ‘it correctly. More recently, a hitherto not investigated but quite common eye defect has been found which will be referred to as aniseikoniav and involves diiïerences in size and/or shape‘of the ocular images in binocular vision, also referred to as eikonic conditions. The term “ocular image” describes the impression formed inthe higher brain centers through the vision of one eye. It isA determined not only by the properties of the dioptric image that is formed in the retina of the eye, but also by the modifications imposed upon that image by the anatomical properties and physiological processes by which this image is carried to the higher brain centers. Methods and instruments forl evaluating aniseikonias are for example described in the Patent No. 1,944,871 of January 30, 1934 to _Adel bert Ames, Jr. and Gordon H. Gliddon', and in the Patent No. 1,954,399 of April 10, 19,34 to Adelbert Ames, Jr. Spectacles for correcting aniseikonias, also referred to asl iseikonic specta .5) ~ ~ there is only one. _ ‘ Y It is therefore one of the objects of this in vention-,to provide a method and means’for cor recting distortional aniseikonia by distorting the image` formed on the retina of .an eye without changing the direction of the line of sight'. Such means, however, which could introduce . corrective distortion ’without unwanted change` of vergence, would in many cases change the 10 dioptric and/or overall and- meridional magniñ cation properties of the eyes introducing thereby these types of aniseikonia. It is,`therefore, an other object of this invention to provide> methods and means for correctively distorting the image 16 formed on the retina o! an eye, while at the same time controlling the >dioptric and/or overall and uniformly meridional eikonic properties o1' the eyes.` » ` If prisms are used to correct» phoria only, `no distortional aniseikonia being present, the dis tortional effector the prisms introduces the lat ter defect to the disadvantage of the wearer. Our invention permits, in another'aspect thereof, a change of vergence, or direction of lines o! sight. 25 without distorting the’image, or by introducing a predetermined. amount of distortion and at the same time, if required, controlling the> dioptric, andeikonic conditions. In its general aspect, the invention has there- ' cles, have also been developed and are described for example in the Patent No. 1,933,578 of No fore the object of providing a method and means ' vember 7,' 1933 to Adelbert Ames, Jr. and Gordon H. Gliddon. Such iseikonic spectacles change the magnification to a predetermined degree and defects, and overall, meridional and distortional .» aniseikonia o1' the eyes, whereby any one, sev 35 may or may not have in addition a .specified~ dioptric effect. n 40 l the patient to see `two objects where in reality Aniseikonia may be of the so-called overall type in which one image is larger than the other in all meridians, or it may be meridional, where one image is larger than the other in one merid ian. Meridional aniseikonia may be uniform with respect to that meridian, or it may have the ., form of distortional disparity >along that merid ian, principally the horizontal one?. ' -Disparities of the latter type correspond to the effects of prisms, which distort an image in the meridian in which they bend the line of sight. Therefore, prisins can be used for compensating or rectifying such distortional aniseikonias. However, ordinary prisms used for correcting this defect would change the -vergence of the eyes and introduce a new defect equivalent to muscu 55 lar defects as phoria or tropias tending to cause for evaluating or correctingphoria and dioptric eral, or all of these defects may be inherently present, `or introduced by correcting one, orsev eral of the other defects. ' These and other objects, features and aspects of our invention will be apparent from the 1'ol 40 lowing detailed explanation thereof illustratingv its genus with reference to general practical embodiments. The description refers to drawings in which: i “ Fig. 1 is a schematical representation .of the 45 distortion effect of a prism; ‘ Fig. 2 is a diagram showing the relation be tween distortion and magniñcationzof a prism; Figs. 3 to 6 are .diagrams explaining the effect of prisms upon the horopter; ` » ~ .. Fig. '7 is a diagrammatical representation of apparatus for carrying out partition measure- p ments; f ,. Figs. 8 and 9 are diagrams giving the relations between distortion,v prism power and base cuí‘ve; 2f 2,116,132 Fig. 10 is a plan view, partly in section, showing a spectacle frame in which is mounted one em~ bodiment oi’ our invention; Fig. 11 isa vertical cross-section of Fig. 10 l taken along line II-Il thereof; ` Fig. 12 is a diagrammatic view illustrating the method of designing a distortionless prism; ' ` Fig. 13 is a vertical cross-section of a slightly modiiled form of our invention; lo Fig. 14 is a horizontal cross-section of the de .vice shown in Fig. 13, taken along the line Il-M -thereof; ' - ` Fig. 15 is a diagrammatic illustration showing our invention in position before an~ eye; Yu Fig.4 16 is an elevation of the principal lens used in trying out our invention; . „ Pig ¿asis a front elevation view, showing a spectacle frame in which `is >mounted oner eni .bodiment of our invention; n- l f Fig. 181i: a cross-section oi Fig. 17 taken along line Il`-'-|l’thereof; , Fig. 19. is a cross-section o1' Fig.,17, taken along - line Irl-._.k-IQ thereof; l ` y , , I , Fig?èfm is’l a'partial sectional view similar to g5 Fig. ìßiggshowing'a modification; k Figa-121- yis a cross-section of Fig. 20; taken along line 2lb-_2i thereof; ' 'Á , " , Fig,;22fls a >view similar to Fig. _20,_showing an , otherfmodiflcation; . ` ' . ` n - ' Fig. 23 'is a cross-’section of Fig. 22, taken along line 23"-2I`thereof; ' Y ` Fig. 24 >is a diagrammatic illustration showing one embodiment of our invention in position'be fore an eye; and> ß v j ~ Figs. v25 and 26 show lens combinations accord ing to Tables V1I.a.n_d_V'lII.` f y ' For a better understanding of the invention, the distortion eii'ected by prisms, and the- dis tortional aniselkonic defects 'of the eyes .will iirst ‘o be> discussed.l The distortion of an eyeglass'for a given iixa tion distance will herein be understood. to mean the change in the per cent magniiìcation oi' the eyeglass for increasingperipheral angles. Anal distortion line D. The intersect Mo on the mag niñcation axis is the overall magniiication of the prism in the plane of the deviation, and, for pur poses of this invention, indicates the magnitude of magniilcation of the zero eil'ective power lens 5 necessary to counteract this magniñcation, as will 'be explained more in detail hereinafter. We observed that, physiologically, the path ological distortion of 'the ocular images (prin cipally in the horizontal meridian) vcausing the 10` above-mentioned distortlonal aniseikonia is,'gen- f ' erally speaking, of the same nature as the just described distortion effected by prisms. It is further afact that, in binocular vision, the mag nitude of the two ocular-image distortions deter- 15 mines> the shape of the longitudinal horopter. The horopter, which may be deñned as the sur face in space, every point on which is imaged on corresponding retinal points, is substantially sym~ metrical with respect to a'vertical plane through 20 the medial line of sight of a 'person having no'y eikonic defects. If, however, the ocularimages or portions thereof have di'iîerent sizes, one and the same object appears smaller to that eye which ` produces >a morev extended ocular image. This 25 causes in binocular vision an apparent change in location and/ or shape of the object. For example, a4 diiïerence in overall size of the ocular images produces> a rotation ofthev longitudinal horopter, which may be describedas the intersection oi 30 the horopter surface and fans of projection lines Afrom they m'ean nodal points of the eyes, these , fans being coniined in ahplane through these nodal points. 'I‘his rotation of the longitudinal horopter appears to take place about a vertical axis pass- 35 ing through the point of fixation at which the eyes are looking, the- horopter portion at the side of the eye with the larger ocular image appearing more distant. ` . ~ ` Fig. 3 indicates the location of the longitudinal 40 horopter‘of a person with normal eyes, H being thev horopter4 trace (which may be for a certain visual distance b a straight line), and F a fixa ¿5 ogously, it will be the change inthe per cent ' tion point', determining vergence, at the distance _b .difference'in the angular size of the kobject and from R and L, the right and left eyes, respectively, 45 . the image produced `by'the eyeglass, reckoned from the anterior nodal point of the eye, for increasing values oi' the angularsize of-the ob w ject. Thus, for a distortionless lens this change will be kzero, while fora pin-cushion distor tion _it will vary, increasing with ythe increase in the angular size of thevobject. of the observer. Fig. 4 shows the location of the horopter trace H1 if, under otherwise similar con ditions, the ocular image of the left.eye is larger, A due to the interposition of a size changing lens S before that eye, orto a corresponding patho- 50 logical diiïerence of the Ocular images.> . Distortional` aniseikonias, either inherent or in troduced by prisms, have> the‘eil'ect of apparently ‘a the plane of the deviation is, within about 20’ curving the horopter, in a manner indicated in ` of the deviation, that of a constant change asv Figs.V 5 and 6, Where H2 and Ha are the longitudi'- u Y 'I'he type oi' distortion 'exhibited by prisms in nal horopter traces apparent to normal eyes due indicated in Fig. 1, where O is an object in the form. of 'a divided square, which appears dis torted-as shown at O’ if viewed through a prism 00 P. It will be evident that meridian d, and simi havingv'a corresponding distortional aniseikonia - larly- any inclined meridian, is distorted as in . dicated at d’. Thus,- as graphically shown in be measured with instruments of the general type described _in the> Aabove-mentioned Patent No. Fig. 2, the distortion vof a prism P will Vbe‘rep resented by an approximately straight line D " 66 _(related to the position of the prism as indicated in Fig.v 2) in a system.“ coordinates represent ing magniiicationv l,l and oblique angles qb, (see Fig. 3) respectively.magnitude of the dis vtortion, above deñnedfps the change in per cent to prisms P2 `and P3, respectively. Abnormal eyes produce a similar eiïect'. » Defects of this type' can 1,954,399. A patient having aniseikonia exem pliñed in Fig. 5 would move the points of a horop ter instrument to actual positions indicating 65 trace H', in order to see them apparently placed as indicatedA by ytrace H". By placing before the patient’s eyes distorting prisms which produce coincidence of apparent horopter and actual ho 70 magnification per do'ëree (¢)_ and herein called Y ropter instrument setting, that is, which move 70 H' and H", itis possible to correct this defect which, even if present 'only to a very low degree, may cause serious illness. 7g is then graphically expressed by the slopel oi the A convenient way to measure distortional an iseikonia quantitatively is the so-called “Multiple »75 3. 2,118,132 Partition Test" which is based on the same prin ciple as the horopter experiments, and which is conducted as follows: A series of object points are also intermediate cases requiring ‘correctionv of both distortionally eikonic and muscular de represented by threads or wires are arranged so that, as seen by each eye, all appear` equally sep arated directionally. As shown in Fig. '7 in oblique projection, a. series of- wires W, W1, W2, etc., and W1 and Wn, etc., respectively, is placed before each eye. Wire W serves as a fixation object and 10 may be iixed, as well as W1 and W1, the distances W, Wi and Wr being kept constant. The other wires are laterally movable and the patient, looking at W, W1, W2, Wa, W4, Ws with the right eye adjusts the wires so that they appear to bc fects, and therefore `control of both distortion and deviation of the lines of sight by _optical means. Inaddition; it may'beuneçessary to cor rect dioptric defects ‘andw'eikonic defects other than distortion.~ ~ _ y " According to our invention, we` control the effect of lenses including prism elements `by ap propriately curving or bending prism compo-nents and, yif desirable, combining them with other prism components and/0r lens elements not directly influencing the direction of the line oisight.I , M For purposes of- our invention, it is necessary 15 equally spaced. If he has a distortional defect,the wires will actually be unequally spaced, and their positions provide a measure of the amount of dis to correlate ythe various characteristics of optical tortion, which can be checked with the aid of prisms correcting the defect. The other eye is for preliminary or .approximate computations. 20 similarly examined with Wires W, Wr, Wu, etc., and the combined effective distortion of both eyes must correlate with the unbalanced distor tion of the horopter. , The shape of the longitudinal-horopter, then, 25 is a measure of the unbalanced distortion be tween the ocular i‘mages of the two eyes in the prisms. While this can be done analytically,` it was found that a more convenient way, 'at least is to relate these characteristics graphically, as will now be described. ' f ~ With the above discussed unit for the prism distortion ha, the properties of prisms have been laid down graphically as shown in Figs. 8 and 9. The effect of a prism depends'principally on prism power, curvature (that is the basev curve longitudinal meridian. Hence,- the unit describ ing the distortion of prisms should be of _the order . of changes of the ocular images for correspond 30 ing changes of the longitudinal horopter. upon which the prism is ground), thickness- of the prism, distance of prisinffrom eye, and‘de gree of tipping with respectto the visual axis. In these graphs, the distortion ha (already de Thus, the unit of prism distortion may be de fined to signify 0.1%vv magnification change per one degree peripheral angle.` A prism having a unit of distortion when placedV before one eye of fined as the change in per cent magnification per unit peripheral angle) is plotted against> the an ideal observer at a definite fixation distance, would cause the horopter trace of zero or un base curves B in diopters, for various prism pow ers A. As minus base curves are indicated Athose which .result in lenses concave~ to the eye, 4and asA plus ba'ses those which result in yocular sur faces convex to the eye. Intermediate prism balanced 4distortion (also called Vieth-Müller cir powers are omitted for the sake of clarity. The cle), to recede to the frontal plane. Now in horopter theory, the distortion is defined as curves are drawn for a distance of about 23 mm. 40 dM from the anterior prism surface- to the -nodal point of the eye, that surface being always per pendicular to the line of sight. Fig. 8 showsthe relations for infinite or relaxation kvisual dis that-is the change in magnification per tangent of peripheral angle, and h=2a/ b when the longi tudinal horopter lies in the frontal plane, where 2a will be the interpupillary distance and b the distance from the median nodal point oiî> the two eyes to the point of fixation. If the above ideal tance (that is, the distance betweenfnodal'point observer is assumed to have an interpupillary dis tance of 60 mm. and if his hcropter race is to be taken at l m. distance from the eyes (compare Fig. 3), then the value of h for this change is -of Fig. 1l offrabout 1 mm. and varying center. thickness t, but could also be computed vfor con and theobserved object), to which a distance of L about 6 m. is practicallyequivalent, and Fig. 9 is similarly drawn for `reading distance, of about 40 cm. For the sake of practical convenience, the curvesr are made up for a constant trim (t' stant t. Similarfcharts can be made up for dif- y >ferent distances from the eye to the prism. These graphical representations of prism char acteristics which, as already pointed out, are especially convenient for purposes .of the present The optical prism distortion is defined, however as invention, can be obtained empirically by actu h--qg-Oñàaos ’ dM ha _”d; X (100) 00 ally measuring prisms, or by conventional tri- 1 ` angulatìon ray tracing methods well known in the art of optics. While our invention provides for general c_on trol of distortion, deviation of the line of sight` and dioptric and eikonic defects by appropriate, ly bending prism elements and in certaini in-v for the values given above stances combining them with other similar _or different optical elements, two especially signifi cant embodiments thereof are the correction of ` distortional aniseikonia without affecting the It will now be evident that conventional. prisms use_d for correcting vergence (phoria efects may introduce eikonic disturbances and’t‘hat, on the other hand, conventional prisms used for correcting distortional aniseikonía would most likely cause a cha-nge in the relation of the lines 75 of sight of the eyes equivalent to phorias. There i lines of sight, and of diverting the latter for corrective purposes, without introducing distor`-4 tion. The latter is’the -»simplest ymodification which may be called “Distortionless Prism”` and f will first be described. Prisms of thisl type are especially valuable in phoria cases which could Il», 4 ~2,118,182 not be corrected with conventional „prisms be causeof the distortion» thereby introduced. the center of rotation of the eye and perpen dicular to a straight axis between the eye and the object, has been found to have a practically » In Fig. 10 there is shown a spectacle frame con sisting of a pair of double rims l for holding the negligible distortion. lenses, a bridge member 2 connecting vsaid rims, and a pair of temples 3, hinged at 4 to endpieces 5, which are in turn secured to portionsof the rims I remote from the bridge »2. , , below. Y _It will be obvious that any suitable well known necessary, the spectacle frame illustrated being' shown byy way of 'example only. Also, it is in certain instances possible to join the lens ele ments directly, for example by cementing, and to , As Üwill now „be -*evident from _the preceding discussiony of the relation of prism power, base curve and distortion, it is possible to ?nd prisms having a'particulary curvature in the plane of the base-apex line as shown at 'l and 8 on the . ‘ In making prisms curved as above described, it has been found that the elimination ofimage form of lens holding means may be used, or that a special type» of> frame may be designed if found mount them'in a more conventional frame.. f 'I'he characteristics o1' a series of prisms of this type, in steps of one A, are given in Table I distortion inthe meridian of the base apex line ofthe prism, is accompanied by a change in the size of the image >in that meridian so that the image would appear in its approximately correct size in vthe meridian perpendicular to the base apex line,Y but would appear of a different size in 15 the meridian of -the base apexline. Therefore, such cylindrical prisms, if usedbefore one eye only, would produce a relative `difference in the shape oi' the two ocular images. When distor tlonless prisms of equal power are put before each lens 6 of Figs. 10 and 11, which prisms bend eye, no differences in the relative shape and size the. line of sight without distorting the image in ~ of the ocular images are produced.y While such the plane of the bending or, in other words, pairs of cylindrical prisms are of practical use, `which have zero distortion h. together with a they have the disadvantage that, even when so predetermined prism- power A, suited to correct used, they make objects appear broader than 25 high. In order to bring the image back to its the ocular defect of an individual patient. proper proportions the lenses 6 have also been The data of a» prism of thistype may in any curved in the plane perpendicular to the base 30 instance be found either ldirectly by means of previously prepared graphs Asimilar to those of apex line, as indicated in Fig. ll, so as to change the size of the image in that meridian. In order 30 that the size of the images in both these meridians be exactly the same,'the curvatures ofthe prisms in the two meridians must be slightly different. 'I'hat is, the lens must beof torio form. Table III gives- the curvatures in the two meridians neces sary to equalize exactly the size inboth meridians `for a series of prisms varying by steps of l` prism Figs-8 and 9, or by a trial and error method con sisting of two main steps. ' ' ` ’ First, a prism i6 (referring> to Fig. 12) of given parameters is laid 'out and computations are made to determine-whether or not that particular set of parameters gives the desired deviation.V Such computations consist of tracing‘an axial rayV of light i'l~ from a point i8' representing the center of rotation of the eyethreugh the prism Vi6 at the diopter. angle I9 whichit is desired to cause the eye to turn ln viewing a given object 20. This ray re turns to, -or >intersects Athe normal line of sight are shown for a series of prisms in Tables I and n. l (angle of devianon=à=4255o 75, when placed with its first surface 40.24 mm. from 55 CoNs'rAN'rs or DrsroarroNLEss` P_Rrsns Assuming the eye turns to take up prism power first surface of lens is 28.83 mm. from center of rotation.` of eye y60 Prism power' A ' prism power of 7.3884 50 TABLE I set of parameters, untill one is found which ~70 concave curvature cf 68.7983 mm. radius . practice such types of spherical meniscus prisms are most useful. Theyalso have the advantage of- being much more easily and cheaply made. ess must be repeated, taking a prism of a different vByway of example, a prism 5 mms-.thic ` . difference between the ocular images if a single prism were used before one eye, they would not if equal prisms are placed before both eyes. In If the two oblique rays are about equal distances from the axial rayl at 26 and 21 (the distance of the object from the eye), therevwill be no distor _tion of the object. If theA distortion properties of the‘prism prove to be unsatisfactory, the proc ~ a convex curvature of 52.6714 mm. radius ' _ While such 'variations would cause too great a eye. Second, the distortion is determined- for the prism which is selected by the first step, by means of `tracing two oblique rays 2| 'and 25, having equal angles of Obliquity, from the point i8 re‘p resenting the nodal point of the eyethrough the base and apex portions of the prism respectively. The rays are traced by the method commonly known in the art'of optics as triangulation ‘ ~ the images will be produced. These differences 2iv (along'which the eye would view the object a, directly) .at 23, the distance of the 4object from the eye. If the ray does not intersect at 23, the parameters are changed until this/ray i1 does meet the line -2| at the proper distance from the will satisfy all conditions. ' I If the curvatures in the two meridians are made the same, that is if the lens is given a meniscus 40 spherical form, someY differences in the size of Angle between the . Cog-"ex ra lus at axis' degrees l 2 ~ two [aces of the Thick' Coâlyex prism 1. 095 2. 190 3. œß 4. 373 the » ness ra ius mm. mm. mm. 2. 95 2. §55/ 2. 95 2. 95 5l. U6 5‘0. 66 49. 66 48. 68 50. 65 49. 64 48. 65 47. 67 5. 439 2. 95 47. 73 45. 71 5. 461 4. 754 45. 53 43.90 6. 543 7. 623 8. 697 4. 75 4. 75 4. 75 45. 97 46. 42 46. 88 44. 33 44. 78 45. 25 9. 766 4. 75 47. 36 45. 73l 10. 669 4. 75 47. 78 45. l5 70 anais: TABLE IIv seikonia can be enacted by introducing cylindri cal size changing components, for example by _ . MAGNIFICATION oF THE DIsToRTIoNLnss PrusMs 1N making lens 9 toric, or by adding Surfaces hav THE HORIZONTAL MIIBIDIAN AND THE VERTICAL ing a similar effect. y „ to 'a change in size, and in that lcase a power lens may be added, or a lens I2 (Figs. 13 andr14) may be substituted for lens 9 of Fig. 10. Lens I2 is of the general type -of focus and size correcting 10 lenses likewise described in the above patent and Magnification Magnin cation vertical horizontal percent percent Prism power A „ desirable to provide a change in »focus in addition First surface of lens is 28.33 mm. from center of rotation of eye 10 . In certain cases of ocular defects it may be MEBIDIAN may be designed as a singlelenswith `curves I3 Aand Il changing both magnification and size to a prescribed degree. : . y ~ ` I . Recapitulating,` for providing> a devlation'of 15 the line of sightwithout `introducing prismatic distortion, and at the same time accounting for prescribed magnification and dioptric character istics, We first determine the proper curves for the prism lens 6 in itsapex-base meridian so that it will bend the line of sight-the required amount but will not distort the image in that meridian. Next, we compute the curves necessary in the TABLE III 25 meridian perpendicular to the apex-base merid RADII IN THEHORIZONTAI. AND VERTICAL MERIDIANS ian to change the size of the image in that me To PRODUCE THE' SAME MAGNIFICATIONl IN THE » ridian by the same amount that the curved prism HORIZONTAL AND VERTICAL MnnIDIANs First surface of lens is 28.83 mm. from center of ' . lens is then ground and finished. rotation of eye ' . _Horizontal 30 Prism willchange it in the apex-base meridian. This po wer Aì Vertical ' Next, we’compute the curves for the lens 9 or I2 necessary to change the size ofthe deflected image back to the desired size. ~ If the focus is not to be changed, a lens like the lens Bis used, but if the focus is `to lbe changed, a lens like I2 Ri Rz , r R: mm mm mm. mm 5l. 66 50. 66 49. 66 48. 68 50. 65 49. 64 48. 65 47. 67 51. 48 49. 98 48. 47 46. 99 50. 47 48. 98 47. 48 46. 00 used. After these computations have been made and the lens 9 or I2 has,be'en ground Yand finished, the prism lens 6 and the lens 9.or I2 are mounted 47. 72 46. 71 45. 23 44. 26 45. 53 43. 90 44.00 42.41 ‘ 45. 97 46. 42 46. 88 47. 36 47. 78 44. 33 44. 78 45. 25 45. 73 46. 15 43. 74 43. 53 42. 73 42. 00 41. 23 42. 16 41. S0 4l. Z) 40. 50 39. 75 in a lens holding means', such `as thefspectacle frame shown, by whichvthey are held in añxed 40 and proper relationwith respect to eachotherk Rx or an equivalent structureeiîecting both size and ' dioptric changes to `predetermined. degrees is / As was mentioned before with reference to Fig. 2, the prism which is curved in both directions to the' proper degree _for avoiding partially or en tirely all distortion, and bends the line of sight as desired, effects in addition a change of the size of the ocular image in all meridians. This overall size change is equivalent to the effect of a plane parallel plate of the thickness of the prism at the line of sight and is, therefore, indicated in Fig. 2 by the magnification at oblique angle zero. If, for example, a different prism correc tion is given for each eye, or if a different mag niñcation is required for each eye, for example due to inherent overall aniseikonia, the magnífi cation properties of the prism must be corrected. For this purpose, according to our invention, we place in series with the prisms 6 (Fig. 10) the and are supported in the proper positionon .the face of the wearer. ï ' It will also appear that we have `provided, in 1 this embodiment of our invention, a new means 45 of changing the direction of pointing of an eye` without distortion and with controlled magniñ cation. In doing'this we first place-before the eye I5 (Fig. 15) a distortionless magnifying prism Y lens 6, and then place a secondf'lens 9 or I2 be 50. fore the eye in series with the first, said second lens having the proper curves. thereon to com pensate for the change in the size introduced in the image. This meansthatthe line of sight is `first bent without distortion„butA with change in 55 size of the image, andrvthatuthe y_change in size is then compensated for`_„ 'This order may be re versed by a Vcorresponding"change in the curves of the lenses.' Accordingly, in Fig. - - f ,points Pi and Pz, at equal lenses 9 with curves III and II which change the size of the imageback to its natural size or to a distances from the linefof sightv, represent an object which is imaged. at Pi', P2', which image points, due to the function of the distortionless size desired, without changing the dioptric posi prism, are at equal distances from the deviated 65 tion of the image. . line of sight c', the distance P1’--P2' being equal ` These lenses are designed to have no focal power when they are at a specified ldistance be fore the eye with an object at a specified distance. By the term effective “zero power” it is meant that the lenses do not change the vergence of the incident light, that is the object and the final image are at the same place. A method for calculating'such lenses is given in the above- v mentioned PatentA No. 1,933,578. It is evident that corrections of uniformly (as 75 353 distinguished from distortional) meridional ani to distance Pi--Pz due to the effect of size element 9„,which, as indicated, retains the image plane in the object plane. It is evident that by impart ing a different magniñcationtoelement Y9, dis 70 tance PIL-P2’ can be increased or diminished and that, by giving to the surfaces of 4element 9 unequal curvatures, Vergence power can be intro duced, removing the plane of P1'--Pz’ from plane P1--,Pz. .It is further understood that vsuch mag 76 niñcati'on and power effects can be made -sym«- 2,115,132 metrical to any meridian instead of, or in addi The second above-mentioned speciñc embodi tion to, corresponding overall eil’ects. Instead of calculating the lens combination for ment, namelyr the correction of ldistortional zero distortion, -the vprism component 6 can be aniseikonia Without bending the line of sight, with the aid of so-called “Distortion lenses” will chosen to have a Vpredetermined prism power to gether with a, chosen distortion. Again, graphs now be described. As shown in Figs. 17 and 1.8, a pair of distor- 1 similar to Figs. 8 and 9 can be used for this pur tionless prism lenses 6 designed as above de pose, or theprisms can be computed by conven tional trial and error methods, in which `case, '- scribed and having curved surfaces 1 and 8, are 10 referring now to Fig. 12,> the oblique rays 24 and mounted in series, respectively, with' a. pair of 25 will be so traced and Vselected that unequal ` prism lenses |09 having iiat or plane surfaces ||0 10 distances ‘from 20 `and 2l represent the desired and ||| thereon. These lenses areso mounted distortion. Examples ofsuch prismatic elements that the bases of lenses 6 are opposite lthe apices are Agiven vbelow-in Tables IV, V, and VI, which of the lenses |09. By this means, as will readily be apparent, theimage coming to the eye will list series of prisms having distortion in con venient steps, each series having a constant prism first be deilected by the distortionless prismv 6. power of one, three and ñve A, respectively. In Then, as the image passes through the flat prism ’ this case, points P1’> and Pz'of Fig. 15 would be 9 it will be deflected in the opposite direction and 20 . distorted. `Hence, the deilections cancelling one unequally spaced in relation to v' another, only the distortion effected by prism |09 e TABLE IV remains. In addition, the image will be mag 20 niñed. ‘ . ‘ Drsmarrorz or Smau Pnrsn-Powna 1A In the case of this specific embodiment called ’ “Distortion lens”, the prism powers of the lenses 25 Umu 0 r (umion «M 1w am 1) d tm, _ o A _`‘ u ms" For? P mof curve dioptel’s (related to eye) ` h-` 6 and |09 are made the same, so that the line of sight enters the eye with no resultant deviation. It is, however-,clear that by'making the prism ‘ 25 powers of the two lenses 0 and |09 different, a 0. 00 0. 00 0.0015 0. 0100 0.0m 0.0125 0. 0250 0. 0315 0.0000 ` 0.0500 K --8. 40 Concave. resultant deviation of any desired amount may _1.54 D0. +0. 00 Convex. +13. 25 D0. +2050 ' accordance with the more general aspect of our invention. D0. ' . ' If. the prism powers of the two lenses, for ex ample 6 and |09, are made the same, thenthe TABLE v Drsromon or Smau: PmsM-Powrm 3A 35 the lenses„but without'deviating the line of sight. Uma of . h . «0M-0% ' A «uM-1) l-` Y 0n u d tan ¢ 0.a) « 0.00 Bm, Form oi cum plriïnà (re dmpters negato _8. 60 Concave 0. 0150 0. 025 _3. 15 0.050 +1.25 convex 0.015 +5.00 D0. 0 0500 0. 015 0. 100 0. 125 D0. D0. 0 000 0.150 +1100 +15. 01 +20. 50 Y ‘ ' has been curved in both directions to the proper degree to avoid entirely or partially all distortion, and prism |09 bend the line of sight as desired, but at the same time change the size of the image 40 no. seen therethrough in all meridians. Therefore, if a patient required a different distortional cor Do. 45 TABLE VI see images of. diiïerent size. Drs'xmnox or SxNaLaPaIsu-Powna 5A am“ h' ¿(51 1 «M 1) _Á° ß-`- d0 Hand» Ba“ For? or p m curve 0.00 " 0. 00- 0. 025 0.050 0. 075 0. 100 0125 -aso 0.015 0.000 0. 045 0. 050 0.015 -5 15 --2. 15 +0. l35 +3. 00 +0.00 1. 1. 2.00... 2.25 0.000 0.125 0.120 0125V 0.150 +8.88 0.115 +1118 0.000 +14.12 0.225 +1100~ 2.50....---- 0 150 0.250 D0. D0. Convex no. D0. D0. D0. no. D5. +2050 _ D0. appropriate lens combination, are so> designed that they change both size and focus of the image, both by the prescribed amount'. The'procedure somewhat, although not very considerably, with changes of the visual.- distance, as shown Aby a ^ up for reading of)ove. computati n is analogous to that ` described a gs. 8 and 9, which _are made position, and inñnite distance vision, respectively. -It may sometimes be advis 10 ableto use different-corrections for these two dis tances.V but in most cases computation for one distance ïwhich may be dominant, concerning de sirability of'correction, or for an intermediate distance, for example 1.332D, is fully satisfactory. ' 'Ihe'foregoing tables are computed -for light comingfrom infinity. j 1 » natural .size or to some other size desired without changing the focus. . Again, if it is desired to change the focus of the concave It should be noted that the distortion changes 65 a chosen that they will change-the size of the image ' 0. „ (Figs. 20 and 21) with curves ||4 and ||5 so diopters ($19231 0 0. 0. 1. 1. g In such instances, we place in- series f‘with the lenses as for example shown in Fig. 18, namely the prism pairs 6 and | 09-1‘espectively, lenses H3 50 'unal or _ l 35 It will readily be seen- that the prism 6 which . 0.0000 0.0450 55 30 ~ _ - arranca It will also be apparent that we have invented otherwise the same effect as combinations of dat a new means for correcting adistortion verror of an eye vwithout deviation of the line of sight and with controlled magnification. -In doing this we ñrst place before the eye ||9 a fiat prism |00 to obtain the proper amount of distortion to correct for the distortion of the eye, after which we place a distortionless magnifying prism lens 6 of the same prismy power as thelens |09 before the >eye with its base Lopposite the apex of the lens |09.l 10 in order to compensate for the deviation intro# duced by the ñat prism lens 9, _and then we place and curved prisms, namely, one prism produces a distortion and a deviation, and the other a. deviation opposing that of the iirst, without dis tortion. . . r , . As already mentioned, it is further possible, according to our invention, to combine prisms, both curved or one curved and one straight, which produce a prescribed amount of` distortion together ‘with a prescribed amount of deviation of the line of sight. _, TABLE Vn a third lens I I3 or | I6 >before .the eye in series i DIsrolmoN LENsEs-2 Pinsus or EQUAL ` PRISM , withk the lenses |09 and 6 to compensate for the POWER e change inv size introduced by . lenses 6_ and |09. 15 una» of distortion «uM-0% nl“ ' 414,-“ . «uM-1) h1 tan ¢ Base cum lst powerk Bm ¿um 2nd power Form of prismV 5A on o 5A on o Fig. 25.' 20 coo _____ -_ 20 o. oo 0.00 base. 0. 60..... ..- 0. 03 L@..... _- 0. 06 1.50 ..... -_ 0. 09 0. 05 EA‘` 0n -3 0.10 5A 0n -ß , , ’ base. . 5A 0n +3 ase. - Fig. 26. l . base. ase. 0.15 ' 5A on +6 Do. ~ base.v 6A on -9 base. v 6A on +9 k zoy Do. base. 25 TABLE VIII Dls'roa'rIoN LEN sas-_2 PBIsMs oF EQUAL PRISM PowEa 30 ` 30 Iì’àii'; d(M-1)% _d(M-1) curve oi ` 0.00---. 0. 125.-0. 250.-- 0.00 0.0075 0.0150 0.00 0.0125 0. 0250 0.00_.'._ 0.00 0.00 3 A on 0 base_-_. 3 A on 0 base__._ Fig. 25. 0. 25.--0. 50---. 0.015 0. 030 0. 025 0. 050 3 A on --1.50base 3 A on »4.50base 40 0. 76---. 0. 045 0. 060 0. 075 0.100 3 Aon _6.00 base 3 A 0n +9 base.. 3 A on ~-7.50 base 3 A on +12 base- :mien h" __Q-4, _ h“ d tan ¢ 35 Base curve of lst prism Form of 2nd prism ' prism (i A Prism) _ - l A on 0 base_..- l A on 0 base-_-». Frg. 25. 1‘A0n ---1.50baSe 1 A on +6 base.; Fig. 26. 1 Aon _3.00 base 1 A on +12 base. Do. (3 A Prism) 1.00---- « (6 A Prism) _ 3 A on +3 base.- Fig. 26. , 3 A On +0 base.. Do. ’ I 0.00..-. 0.00 0.00 0.50-.-1.00-... 0.03 0. 06 0.05 0. l0 5 A on -~3 base.- 5 A on +3 base.. Fig. 26 5 A on -6 base" 5 A on +8 base;Do; 1.50.--- (),09 0.15 5 A on -9 base.- 5 A on +9 base-_.\ 5Aon0baso.... 5Aon0base_.__ Fig. 25 Recapitulating, the various elements of f this lens combination‘may be computed as follows: First, the proper prism power andr base curve for the prism lens |00 is determined, so that it will produce the desired distortion. This can be -readily done graphically as indicated, orl by trial and error, or by computation, as discussed herein before. It should be noted that it may be desir able to have a greater amount of distortion than can be produced by a ñat prism. In that case, a prism .on a meniscus base, with the lens turned backwar ,is used. Combinations of this type are given in ables VII and VIII. Í The next step is the computation of a distor 00 tionless prism 6 of the same prism power as the distortion prism |09 in the manner already dis cussed. ' 40 D0. Do. l ‘ , ' Next we compute the curves vfor a lens ||3 or IIB necessary to change the size of the distorted 65 image back to the desired size. If the focus is not'to be changed, a lens- like the lens | |_3 is used, but if the focus is to be changed, a lens like the lens H6, or equivalent structure, is used. f After all these lenses have been finished, they 70 are mounted in a lens holding means, such as the Do. This'means that lthe-line of sight is bent, the image at the same timebeing magnified; that the line of sight is bent back to its original direc, tion but distortion is introduced; and that the change in size is .then compensated for. This order may be reversed by a corresponding change in the curves of the lenses. i f Fig. 24, analogous to Fig. 15, illustrates such an arrangement, the distances of points P1” and'Pz" from axis v”, whose direction is not changed, in-' dicating the distortion with reference to the posi tion of object P1, P2. Size compensating yelement | I3 does not separate object and image planes. It will ,be evident that by giving element ||3 appropriate curvatures, any desired lmagniiica tion can be introduced, and that a distance be tween object and image (in Fig. 24 assumed to be in the same plane) can be introduced by giv- » ing element ||3 a certain vergence power in ad dition to its magnification characteristic; It is further evident that the magniñcation and power ~ components may be effective »in any chosen rne ridian as Well as in all meridians, by accordingly shaping the surfaces, if necessary by means of composite lenses incorporating surfaces shaped spectacle frame shown, by which‘they areheld in to accomplish these eiïects. y , face of thewearer, at >the distance from the eyes lsight can be introduced, the kresulting effect be Itis also understood that by making the op e properly fixed relationwith respect to veach other , posing prism powers ofv elements 6 and |09 un and are supported in the proper position on the equal, a predetermined deviation of- the line of for which the lenses were computed. - 4 65 8 , 2.11am: ing in substance the same as that discussed above with reference to Fig. 15. Such a distortion plus deviation lens .comprising two prism .elements may be’ preferable in cases where considerable distortion is required. „ substantially affecting tions and given prism powers that differ in con venient steps (Tables 1V, V,V VI), including se ries with distortion zero (Tables I, II, III) or - element, the said curved surfaces producing in said second meridian a magnification 'substan tially _equal to said magnification introduced by the curvatures in said first meridian without It will ’be evident that lens series with distor 10 prism power zero (Tables V'lland VIII) are use ful for testing eyes for eikonic and muscular de fects, and within the scope of our invention. It is to be understood that wherever a “mag _tionedpmeridian so as to produce a cupped lens saidcompensatory distor- tion and said compensatory deviation. l . 3. An eyeglass for correcting ocular image dis tortion, and deviation of the line of sightbyintro ducing given compensatory amounts of prismatic distortion and deviation, comprising a lens ele ment having surfaces, _each of said surfaces hav ing in one meridian a curvatureand being spaced nifying” prism and a “reducing’f lens are lcalled for in the foregoing specification vand accompa nying claims, both the lensand the prism l may tem effecting said compensatory distortion, said including that provided by lenses 9, I2, H3 or meridian being located withrespect to said first relative to the other forming a prismatic lens sys- l be either magnifying or diminishing, it being only ` compensatory prismatic deviation and a certain necessary that the lens be such as to make the substantially zero power magnification yin said „ Í image its proper size after its sizeV has been meridian, and a second lens element having sur faces, one convex and the other concave, each of changed by a prism element. the surfaces of said second element having a ’ It is further understood that, at least in cer curvature in’y a compensation meridian. being tain cases especially favorable for such proce dure, the entire size and/or dioptric correction, » spaced relative to the other and the surfaces Aof* l It (Figs. l0, 13.20, 22) can be incorporated in the element. or elements, having the prism eñect. From ¿the foregoing description it will be seen said ñrst 'lens element and said compensation mentioned meridian to produce in said compensa tion meridian -a magnification substantially equal that we have provided methods and means forV to said magnification.intrcduced- by the curva carrying out all the objects of the invention, and tures in said first meridianwithout substantially affecting said compensatory distortion and said that we have provided means for correcting dis tortional‘aniseikonia and phoriaor for `correct ` >4:. An eyeglass for correcting ocular image dis .compensatory ing distortional errors of the eye without chang ing the direction of the line of sight of the eye, or for correcting the direction of the liney of deviation. , . » y » - ` f tortion and deviation of the line of sight by intro sight without introducing distortiom and, in all .ducing given compensatoryamounts of prismatic distortion and deviation, comprising a’lens ele-` cases, at lthe same time controlling eikon'ic con-l ing in one meridian a curvature and being spaced ment having surfaces, each oi’jsaid surfaces hav ditions other thanl distortional, and the dioptric relative to the other to produce a prismatic lens properties ofthe image, whenever it should be .system effecting isaid compensatory distortion, necessary. deviation, a certain Lsubstan It should be understood'that the present dis ` said compensatory zero power magnification in _said meridian closure is for the purpose of illustration only and -tially, and a substantially zero power overall magnifica that this invention includes all modifications and tion, and each of said surfaces being -curved» equivalents which fall within the scope of the in a -meridian normal to said first-mentioned me appended claims. ` ridian so as to produce a cupped lens element. the V45 We claim: said curved surfaces producing in said second 1. An eyeglass for-correcting ocular image dis tortion, and deviation of the line of sight by in vmeridian a magnification counteracting said troducing given compensatory amounts of pris matic distortion and deviation, comprising a lens system having surface means, each of said surface means having in one meridian a curva ture, and being spaced relative to the other sur face means, forming a prismatic lens system ef 55 Y fectingv said compensatory distortion, said' com pensatory deviation and a certainfsubstantially magnification introduced by the curvatures in sa’idflrst meridian without substantially affect ing said compensatory distortion and said com pensatory deviation, and a second lens element having surfaces one convex and the other con 50 cave, each of said surfaces having curvatures in> two meridíans, aligned with said first-mentioned meridiana, and being spaced relativeto the other and to the surfaces of said first element to pro zero power magnificationxin said meridian, and 55 said surface means being curved in a meridian duce without substantial ,change yof v'vergence normal to said first-mentioned meridian so as to ' power a rgiven overall magnification which, to produce in said second meridian a magnification _gether with that of said first element provides an n substantially equal to said magnification intro->` ' eyeglass with predetermined meridional and over s ` -' duced by »the rcurvatures in said first meridian, all magnifications. 5.> An eyeglass for correcting ocular image dis without substantially affecting said compensa- ` tory distortion and said compensatory deviation. tortion and deviation of the line of sight by in troducing given compensatory amounts of pris 2. An eyeglass for correcting ocular image dis tortion, and deviation of the line of sight by in ’ matic distortion and deviation, comprising a lens element having surfaces, 'each of 4said surfaces 65 troducing given _compensatory amounts of pris ~matic distortion and deviation, comprising a f having in one meridian a `curvature and being spacedrelative to the other to. produce a pris lens element having surfaces, each of said sur faceshaving in one meridian >a curvature, and vmatic lens section effecting said compensatory 70 being- spaced relative to the other forming a distortion, said compensatory deviation, a certain prismatic> lens system effecting said compensa-- substantially zero power magnification inj'said 70 tory distortion, said compensatory deviation and meridian and substantially zero power 4overall rs a certain substantially zero power magnification ' magnification, and' each 'of said surfaces being curved in a meridian normal to said first-men tioned meridian so as to produce a cupped lens curved in a meridian normal to said first-men in said meridian, and each of said surfaces being element, the said curved `surfaces producing in 75 ' „ à 2,118,132 said second meridian a magnification substantial ly equal to said magnification introduced'by the curvatures in said first meridian without substan tially affecting said compensatory distortion and dium of a given index of refraction and having " surface powers computed according to said in said compensatory deviation, and a second lens element having parallel surfaces one convex and the other concave, each of said surfaces having curvatures in two meridians, aligned with said first-mentioned meridians, and being spaced rela tive to the other and to the surfaces of said first element to produce substantially without change of vergen'ce power, an overall magnification sub stantially equal to that'of said first element, pro viding an eyeglass substantially lWithout, merid ional magnification and compensating the overall 15 magnification ofsaid first element.` ' 6. An eyeglassk for correcting deviation of the line of sight without ocular image. distortion by introducing a given compensatory amount of prismatic . deviation, comprising a lens system dices Vand according to said spacing, with the. surface means of each of said systems being de pendent upon the’ other, said curvatures and said spacing to effect in said meridian a given distortion altering the angles subtended, at aref erence point 'of aneye, by a fan of light rays from object points in a plane through the object and said point to progressively different amounts, substantially-in proportion to said distortional aniseikonia. y ~ r '9., Spectacles for correcting binocular"v vision ' for distortional'aniseikonia of~ an amount vdefined by the tested change in magnification >ratio with changingy peripheral angle,- said spectacles com- 1 prising a frame, and twoïlens systems mounted in said frame before the'respective eyes, at least one of said systems having‘surface' means, 'each ofl said surface means being'spacedï relatively 20 to vthe other and having" in-one meridian a 'cur f having surface means, each of said surface means> ~ vature forming a prismatic lens 'system and'each being spaced relative _to therotl'ier surface means of said surface means beingcurve'd in a meridian to form a lens system having said compensatory normal to said first-mentioned meridian so as prismatic deviation in one meridian and each of to'produce a cupped lens system; the surfaces 25 said surface means having in said meridian 'a of said two systems, v'respectively',*being in said » 25 curvature producing at said spacing substantially frame spaced from the respective eyes, and each zero'prismatic distortion anda certain substan system being formed of lens medium> of a given tially zero power magnification and each of said index ofrefractionand having `surface powers surfacemeans being curved in a meridian normal computed according to said indices and accord 30 to said prismatic meridian to form a cupped lens ing to said spacing, with the surface means of system, the said curved surfaces producing in said each of said systems being dependent upon the second meridian a lmagniñcation substantially ` equal to said magnification introduced by the other, said curvatures and said spacing to ef fect vin said first meridian a given distortion al curvatures in said first meridian without sub 35 stantially affecting said zero distortion `and said tering the angles subtended, at a reference point 55 compensatory deviation. of an eye, by a fan of light rays from object points in a plane through the object and said ‘7. An eyeglass for correcting ocular image dis tortion without substantially deviating the line‘of -point to progressively different amounts, sub stantially in proportion to said distortional anise sight by introducing a given compensatory pris matic distortion, comprisingI a lens system having ikonia, and also producing a certain substantial ly zero power magnification, and said curvature y ing in one meridian a curvature and being spaced in said second meridian producing in that merid relative to the other surface means forming a ian a magnificationsubstantially equal to said prismatic lens system effecting a prismatic de magnification introduced by the curvature in said viation, said compensatory distortion and a cer first meridian without substantially affecting said 45 tain substantially zero power magnification, and given distortion. j a second lens system having surface means 10. Spectacles 4for correcting binocular vision spaced relative toeach other and to the surface for distortional aniseikonia of an amount defined means of said first system to produce a prismatic by the tested change in magnification `with lens system effecting in said meridian a prismaticv changing peripheral angle and for deviating the 50 direction of at least one of the lines of sight to a 50 deviation opposite to and therefore compensating 40 surface means, each of said surface means hav said prismatic deviation of said first system, and predetermined degree, said spectacles compris also effecting a certain substantially zero power magnification, the surface means of at least one of said elements being curved in a meridian nor mal to said first meridian so as to produce a ing a frame, and two lens systems mounted in said frame before the respective eyes, at least cupped lens system, the said curved surface means producing in said second meridian a mag nification substantially equal to said magnifica one of said systems having surface means, each of 55 said surface means being vspaced relative to the other and having in one meridian a curvature forming a prismatic lens system, the surface means of said two systems, respectively, being in tion introduced by the curvatures in said first , said frame spaced from the respective eyes, and 60 merid-ian without substantially affecting 'said each system being formed of lens medium of a compensatory distortion and said compensated given index of refraction and vhaving surface powers computed according to said indices and> deviation. ~ 8. Spectacles for correcting binocular vision according to said spacing, with the surface means for distortional aniseikonia of an amount defined of'each of said systems being dependent upon theo Cl by the tested change in magnification ratio withy other, said curvatures and said spacing to> effect` changing peripheral angle, said spectacles com in said meridian a given distortion altering the prising a frame, and two lens systems mounted in angles subtended, at a reference point of an eye, said frame before the respective eyes, at least one by a fan of light rays from object points in a of said systems having surface" means, each of plane through the object and said point to pro 70 70 said surface means being spaced relatively to gressively different amounts, substantially in pro the other and having in one >meridian a curva portion to said distortional aniseikonia, and to ture forming aprismatic lens system, the sur bend the line of sight of at least one eye to said face means of said two systems, respectively, be degree. , ing in said frame spaced from the respective predetermined l1. Spectacles for correcting binocular vision 75 75 eyes, and each system being formed of lens me 2,118,132 vby deviating the direction of at least one ofthe lines _of sight to a predetermined degree, without introducing ocular. image distortion, said spec tacles comprising a frame, and two lens systems mountedl in said frame before the respective eyes. at least one of said systems having _surface means, each of said surface means being spaced relatively tothe other and having in one meridian a curva ture forming a prismatic lensosystem, and each 10 of said surface means having in said meridian a and two lens systems mounted in .said frame be forethe respectiveeyes, at least one of said sys tems having one lens element with surface means, each of said surface means being spaced relative ly to the other and having in one meridian a curv ature forming a prismaticlens system effecting a prismatic deviation, and a second lens element having surface means spaced relatively to each other and to the surface means of said first ele ment forming a prismatic lens system 'effecting 10 in said meridian a prismatic deviation opposite zero distortion, the surface means oi'.` said two f to and therefore compensatingy said prismatic . systems. respectively, being in said'frame spaced deviation ofl said first element, the surface means vfrom ,thev respectiîe eyes,v >each system' lbeing of .said two systems, respectively, being in said 15 formedßof lena of a given indexpfre frame spaced from the respective eyes, eachsys 15 ‘ fraction and having'surface powers computed lac tem being formed 'of lens lmedium -of a given in curvature producing at said spacing substantially cording to said s» indices f and according to said spacing, with the 'surface means of each _of said systems being ,dependent upon-the other, said dex of refraction and having `surface powers com- - puted according Vto said indices and according to said spacing, with the surface means of each of curvatures and said spacing to retain in said -said systems being dependent upon the other, 20 meridian unaltered> the angles subtended, at a said curvatures and said spacing to effect in said reference point of an eye. by a fan of iight rays 25 from object points lin a plane through the object and said point, and to bend the line of sight of at least ,» one eye` toI saidv predetermined degree. 12.".Spectacles for (correcting binocular vision for-distortional aniseikonia of ‘an amount yde fined by the tested change in magniflcationfwith changing peripheral angle, without substantially 30 deviating the direction of at least one of the lines of sight, said spectacles comprising aframe, meridiana given distortion altering the anglesY subtended, at a reference point of an eye, by a fan lof light rays from object points in'a plane through the object and said point to progressively 25 different. amounts, substantiallyin proportion yto , Asaid distortional aniseikonia, without substantial ly bending the lines of sight of the eyes. ' , ADELBERT AM'ES, JR. GORDON H_GLIDDON. KENNETH N. OGLE. '