US3152594A

US3152594A - Therapeutic eye treating apparatus and method

Info

Publication number: US3152594A
Application number: US134630A
Authority: US
Inventors: Kramer Mary Everist
Original assignee: Individual
Current assignee: Individual
Priority date: 1961-08-29
Filing date: 1961-08-29
Publication date: 1964-10-13
Anticipated expiration: 1981-10-13

Description

Oct. 13, 1964 v M. E. KRAMER 3,152,594

THERAPEUTIC EYE TREATING APPARATUS AND METHOD Filed Aug. 29; 1961 I 4 Sheets-Sheet 1 I MRRY EvemsrKameg 24 1.3 22 [Q4 2 5 BY J 3 I A'rfo Oct. 13, 1964 KRAMER THERAPEUTIC EYE TREATING APPARATUS AND METHOD Filed Aug. 29, 1961 4 Sheets-Sheet 2 \NVENTOK: Mam Evaam KRAMER ATT RNEY Qct. 13, 964 M. E. KRAMER I 3,152,594

THERAPEUTIC EYE TREATING APPARATUS AND METHOD Filed Aug. 29, 1961 4 Sheets-Sheet 3 RETANAL RECEPTION- RETINAL Recepnom Roo SYSTEM Com? SYSTEM Pwmem- LAYeK 3W 0.

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M. E. KRAMER 3,152,594

THERAPEUTIC EYE TREATING APPARATUS AND METHOD Oct. 13, 1964 RT. LATERAL GENICULATE MACULAR AREA M-PAPILLO MACULAR BUNDLE 3RD.ORDER NEURON OPTIC RADIATIONS OPTIC NERVE FIBERS PURE coma SYSTEM -BIPOLAR CELLS I ST.,2 ND. AND 3 RD. ORDER NEURONS OF THE VISUAL TRACT FIG. I9

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S A a mm M DWM 2 C N d R0 8 M A N .ER 1 AP 0 DDU Mi E R RE F E l HG ER 1 ZON Y EVERI ST KRAMER ATTORNEY United States Patent "ice 3,152,594 TEFIERAFEUTIC EYE 'I'REA'IING APPARATUS AND ME'IHGD .MaryEverist Kramendfi W. Cataiina Drive,

Phoenix, Filed Aug. 29, 1961, Ser. No. 134,631)

12 Claims. (Cl. 123395) central area of the eye retina willbe protected from com-' plete light adaptation, while a specific and selected retinal area receives the light stimulus from high intensity illumination with the resulting effect of light adapting said retinal area.

It is another object of this invention to provide a viewing device such as described above wherein the center of the source of illumination is blocked off with an opaque strip which uniquely protects the central area of the eyeretina from exposure to the high intensity illumination.

It is another object of this invention to provide an object of attention by means of a fixation dot, centrally placed inthe opaque strip of the viewing device such as described, for the further purpose of obtaining accurate and central fixation of the eye during. exposure of the selected peripheral retinal area to the high intensity illumination.

It is yet another object of this invention to provide a method of therapeutically treating the eye, in which a negative after-image is produced upon a selected periph eral retinal area while the central foveal-niacular area of the eye is caused to aim toward the center.

It is yet another object of this invention to provide a method of therapeutically treating the eye, in which the eye receives the stimulus to aim to the center by means of the fixation dot while simultaneously bleaching the visual purple of a selected peripheral retinal area, by means of high intensity illumination; after which stimulus the resulting afterimage on the peripheral retinal area will act as a frame of reference for continued central (iovealmacular) fixation while viewing afixation point in ordinary room lighting conditions.

It is yet another object of this invention to provide a method of therapeutically treating an eye, which, through incorrect position or posture, has received an incorrect light stimulus (relative to the normal fellow eye), and has, through practice, learned to make incorrect response to said stimulus. By presenting a correct stimulus with the centroscope, the eye in turn can learn to make the correct response. g

It is yet another object of this invention to provide a simple and inexpensive training device for daily eye practies at home, for patients whose eye conditions would benefit from such therapy, including patients who cannot, because of long distance or'transportation difficulties, make the necessary trips to the eye therapist. It is possible also, for patients who cannot afford therapy with other devices currently available, to use this invention at home.

Some of the objects of the invention having been stated, other objects will appear as the description proceeds when taken in connection with the accompanying drawings, in which:

3,1525% Fatented Get. 13, 1954 FIGURE 1 is an isometric viewer" my improved therapeutic instrument; i v I FIGURE 2 is a longitudinal sectional view taken along line 22 in FIGURE 1; i' v FIGURE 3 isa sectional detail view taken along line 3-3 in FIGURE 1;

FIGURE 4 is a transverse sectional view taken along line 44 in FIGURE 1;

FIGURE Sis a transverse sectional view taken along line 5-5 in FIGURE 1; is

FIGURE 6 is a graph showing certainproperties of various commercially available materials suitable for use as a dark adaptive filter in the present invention;

FIGURE 7 is a schematic View illustrating the manner in which the retina of the eye is stimulated and inhibited simultaneously with the instrument; 7 v

FIGURE 8 is a schematic view illustrating a condition of image suppression in the eyes; i

FIGURE illustrates the positive afterimage seen with a closed eye following two successive exposures to the high intensity light with the instrument held horizontally and vertically, respectively;

FIGURE lOillustrates the negative afterimage seen with the eye open while looking at the letter M on a light colored wall and after two successive exposures to high intensity light during which the instrument is held horizontally and vertically, respectively;

FIGURE 11 illustrates the negative afterirnage seen with the eye open while looking at the letter M on a light colored wall after one exposure to light with the in strument held vertically;

FIGURE 12 is a' View similar to FIGURE 11 but illustrating the negative afiteri-mage resulting from exposure to light with the instrument held horizontally;

FIGURE 13 is a schematic view ofthe right eye showing certain parts thereof;

FIGURE 14 is a schematicview illustrating the rod system of the retina; i

FIGURE 15 is a view similar to FIGURE 14 illustrating the cone system of the retina;

' FIGURE 16 is a schematic view illustrating the arrangement of the nerve fibers in the retina;

FIGURE 17 is a graph illustrating the relation of visual acuity of the retina to the distance from the fovea;

FIGURE 18 is a schematic viewshowing the distribution of retinal nerve fibersof the left eye, with placement of centroscope image and fixation, and

FIGURE 19 is a view schematically illustrating the relationship of the 1st, 2nd and 3rd order neurons to other components of the eye retina. i

The 'centroscope is a device to assist the patient with ocular difliculties resulting from inability or loss of central fixation in one or both eyes. With proper use of the centroscope, the patient can restore or establish central fixation. With the establishment of central fixation, the patient may then enjoy the rewards of increased visual acuity, straight eyes and a normalfusion reflex pattern.

Loss of central fixation can occur from various causes of a functional or pathological nature. It is the loss of -centralfixation 'of functional origin that is benefited by use of the centroscopep In selected cases of pathology that are cured, a residual functional malady can be treated with the cen'tro scope to restore central fixation.

' Central fixation in this context refers to foveal fixation. During treatment procedures, the macular area around the fovea may be used by the patient; therefore, the term "foveal-macular area ofthe retina. The central foveal vision is' almost exclusively cone vision. The foveal area is surrounded bythe macula and this .region contains fective in scotopic vision. The cone vision is most ffective in photopic vision and form vision.

Simply stated, the ccntroscope brings about central fixation by rendering ineffective the rod vision with maximum light stimulus. It leaves no alternative for cone vision in the foveal-macular area, but to aim at the specified fixation point.

To accomplish the fixation with the central foveal area of the eye, the ccntroscope illustrated in the accompanying drawings is employed. The word ccntroscope is derived from three Greek words optikos, tropos and kentron which, when translated to English, means eye that turns to the center.

The centroscope comprises a black rectangular box or housing It having

end sections

11 and 12 removably secured in the respective opposite ends by any suitable means such as screws 14. End section 11 has threadably mounted therein a lamp socket 15 equipped with a con ventional switch 16. An elongated incandescent lamp globe 17 is threadably secured into socket 15, said globe extending longitudinally of and substantially parallel to the interior side walls of housing 10.

The light housing it may be either rectangular or circular in shape, but should be black in color. The globe 17 used in the current model is manufactured by General Electric Company and other electrical manufacturers; and is a clear, 40 watt, 120 volt, Tl0, showcase lamp, with a class B, C-8 filament and approximately 430 lumina, thereby giving the effect of a 600 foot candlepower when the eye viewing it is six inches in front of the instrument.

On the top, back and bottom side walls of the housing It) are small holes 18 for the purposes of dissipating the heat generated from the light source 17. These holes are of some importance when several consecutive treatments are to be performed.

Suitable elongated slots or openings 21 are provided on the front side of wall 19a of the housing 16, said slots being located on opposite sides of a central viewing mechanism broadly designated by the reference character 22 and specifically comprising a target opening 23 and a dark adaptive filter 24 covering the opening. The area of the filter 24 viewable through opening 23 constitutes a fixation dot, usually red. The filter 24 is removably held in position over the target opening 23 by any suitable means such as a grooved projection 25 and a spring clip 26 (see PEG- URE 5). In the present model, each slot 21 is 1% inches long and 7 inch wide. The length of the slot is governed by the length of the filament in lamp globe 17. Inside the housing It) is a light reflecting lining 27 of aluminum foil or other suitable material.

As will be apparent from the detailed description appearing in the specification, the purpose of the shielding of the central retina is to produce the optimum photochemical adaptation for maximum visual acuity. The filter 24, along with the protective shield around it, does this precisely and effectively, irrespective of the distance the ccntroscope is held from the eye. The retina is exposed to the ccntroscope while the fovea is aimed at the filter 24. Immediately following this exposure, the vision in the central area is enhanced because (1) this area has attained optimum photochemical adaptation for acuteness of vision, and (2) greater accuracy of fixation. The former is brought about by the previous shielding of this area by filter 24 and the opaque shield or wall 22a around it. The latter occurs because the previously stimulated peripheral area is photochemically adapted so that it cannot react to a light stimulus and therefore its previously conditioned stimulus-response patterns cannot interfere with the fixation refiex. Since this area i completely light adapted, other inhibitory influences are operative during this period which prevent other reflexes, visual or vestibular, to

function. The fixation refiex has complete freedom to function without interference, modification or alteration. The afterimage in the periphery acts as a closed door, giving the fixation point in space a frame of reference. Thus, the fixational response cannot shift from the central to the exposed peripheral area, nor can a previously conditioned pattern interfere.

During therapeutic exposure, the foveal-macular area of the eye retina is adapted to be aimed at the abovernentioned colored fixation dot of filter 24, which dot is surrounded by opaque black area 22a and, at the same time, unfiltered light of relatively high intensity is projected from source 17, through slots 21, and onto selected peripheral retinal areas of the eye (see FIGURE 7). It is here seen that the foveal-macular retinal area F is prepared for maximum stimulation with filtered light, and that the peripheral retinal area is prepared for maximum inhibition with the stimulating light. Since the middle area of the light source 17 is viewed through the protective light filter 24 of viewing mechanism, a photochemical change in the foveal-macular retina does not occur. The exposed peripheral areas of the retina are bleached (light adapted), rendering them ineffective to receive a light stimulus for seconds (or minutes) after the exposure can receive a light stimulus following the initial exposure.

In FIGURE 1 it will be observed that the two slots 21, through which selected peripheral retinal areas of the eye are exposed to unfiltered light of high intensity, are 10- cated equidistantly on diametrically opposite sides of the viewing mechanism 22 through which the foveal-macular area of the eye is simultaneously exposed to a filtered light capable of supplying a fixation stimulus but without light adapting it. Thus the location of viewing mechanism 22 is determined with reference to the positions of slots 21, the latter serving as guides or reference areas. As will be described more fully hereinafter, afterimages may be elicited from and retained on the selected peripheral retinal areas of the eye thus exposed by subsequently viewing a secondary light stimulus. The exposed fovealmacular area, however, will not produce or retain an afterimage while viewing the secondary stimulus. Nevertheless the correct location of the foveal-macular area may be readily determined by referring to the positions of the retained afterimages on the peripheral retinal areas. Therefore, the retained afterimages constitute a frame of reference designating the central area of the eye.

With the ccntroscope, the patient does the viewing in the center through the filter 24 of viewing mechanism 22. The operator supervises and guides this viewing or fixation or" the central foveal area. Thus the central viewing mechanism blocks off the foveal-macular area from light exposure. The red dot on filter 24, made visible through opening 23 by lamp 17, is a fixation device which induces the foveal-macular area to hold steady. Should the fovea slip off the red dot, there is some protection afforded the;

area surrounding the fovea by virtue of the opaque wall portions disposed between

openings

21 and 23 and de- This is of majorsignated by reference characters 22a. importance, since foveal fixation is very difiicult and many times impossible to maintain in the beginning. If the area around the red dot or opening 23 were not blocked off, then the foveal area would also be bleached or light adapted if the fixation slipped from the fovea onto a surrounding area. The fovea fixates on the red dot at 23, While the macular area surrounding it is protected by the opaque or blocking areas 22a of the ccntroscope (FIG- URES l and 6).

Viewing the red dot through the opening 23 prevents a change of the photochemical substance in the fixating or viewing foveal-macular area of the retina by the patients own effort to look at the round red dot and the operators guidance to assist the patient to maintain steady, accurate fixation with the foveal-macular area during the exposure of the selected peripheral retinal area to the bleaching light. The foveal aiming or fixation on the small round spot of filtered light during exposure of the selected peripheral retina to the bright illumination is of vital importance for efifective therapy (FIGURE 18).

A greater stimulus and therefore better response for foveal fixation is given with the red dot on filter 24, which dot is illuminated by light source 17 behind it. A totally dark target area would afford no fixation stimulus, the latter being an essential requisite in centroscope therapy.

The opaque black blocking wall portions 220 vary in width from 5 to 15 millimeters which, in turn, serve to shield or protect the central fixating area of the eye retina from bleaching and becoming light adapted from the light emitted from slots 21. The lO-millimeter width is the one most commonly used; the greater 15-millimeter width is used for more severe cases and the lesser width of S-rnillimeters for less severe cases.

The dark adaptive filter may comprise a ruby red glass, red Kodaloid manufactured by Eastman Kodak Company of Rochester, New York, or Plexiglas manufactured by Rohm & Haas Company of Chicago, Illinois (see FIGURE 6), or acrylic cellulose acetate, or other material having the same or substantially the same light transmission and which eliminates all but 10 to percent of the red portion of the visible spectrum.

FIGURE 6 explains the photometric curves of the visible spectrum, typical of the various Plexiglas colors. To protect the central retinal area sufficiently, it is necessary to eliminate all but about 10 to 15 percent of the red portion of the visible spectrum in order that no bleaching, sufiicient to form an afterimage, will result. This is accomplished by using red of sufficient density, or by combining various colors such as red-blue or redgreen or red-amber-blue of various densities so that only 10 to 15 percent red light transmission occurs. This is done so that no afterimage is formed in the foveal-macular area following the centroscope stimulus, indicating that no bleaching of the photochemical substance has occurred. v

Any light transmissible material which will protect the fovea from bleaching of its photochemical substance other than that accomplished by ordinary room lighting, yet maintain sufficient brightness as a fixation stimulus, is a suitable medium for viewing through the central viewing mechanism 22. Red Scotch tape, commonly used for Christmas wrapping, has been used effectively for this purpose.

Where change from the standard techniques is indicated, it has been found that this can be done by changing the distance between the eye and the centroscope, foreshortening the distance for greater brightness, and 'increasing the distance between the eye and the centroscope for lesser brightness. In those cases of so-called eccen tric fixation where the vision is so markedly reduced that the patient has no ability to aim or fixate with the foveal-macular area of the retina, then it is necessary for the operator to supervise carefully and instruct the patient to fixate on a point that would bring the foveal-macular area into line with the central viewing mechanism, thereby sparing it from the inhibitory and bleaching effects.

Although defined in specific terms above, it is evident that the centroscope may assume a variety of structural sizes and forms without departing from the spirit of this invention.

THE RED FILTER FOR DARK ADAPTATION Investigators in the field of dark adaptation have not been able to explain physiologically Why red light preserves the dark adaptation of the retina. Advising the use of the red filter to achieve dark adaptation is based on the following experiment: Following an exposure to red light, dark adaptation is much faster than following a pre-exposure to white light. This completely confirms the practical experience of the last war. All personnel engaged in night flying, where dark adaptation was of importance, wore red goggles whenever they were exposed to light bright enough to interfere with their dark adaptation. According to Hecht and Hsia, researchers in this field (Hecht, S., and I-Isia, Y: Dark Adaptation Following Light Adaptation to Red and White Lights, I. Optic. Soc. America 35:261, 1945) the real reason why red light or red transmitting glasses or filters are used for achieving dark adaptation depends on the relative positions of the two luminosity curves on the wave length scale of the spectrum. The effectiveness of the transmitted red light is the area under the curve to the right of a vertical line at 620 millimicrons (FIG. 6). For the photoptic curve the ratio between the relative brightness of the whole light compared to the red light is nearly 10, which means that if, for the cones, whole white light is to be made equal in brightness to the red light transmitted from it through the red filter, the whole light has to be reduced its intensity by means of a neutral filter or any other device which decreases it evenly along the spectrum. The real values depend on the energy distributions in the spectrum of the light used and the transmission of the filter. It is thus seen that red light is more effective than white when used for the purpose of maintaining dark adaptation. The red filter is used also as a therapeutic device in strabisrnus when the subject is sensitive to light and has a tendency to close one eye when going outdoors into ordinary bright daylight or into a room with bright illumination.

PHYSIOLOGICAL SIGNIFICANCE FIGURE 13 schematically illustrates the relative positions of various parts of the right eye. The fovea is composed entirely of cones. These cones are the most sensi tive to light and are able to distinguish the finest detail.

To quote Adler, p. 536, Physiology of the Eye, C. V. Mosby Co.: The pure cone system (fovea) is made up of the following three links; the cones, the bipolars and the ganglion cells (see FIGURES l3, l8 and 19). Each cone is synaptically related to a single bipolar which, in turn, is synaptically connected to a single ganglion cell. Each of these units seems to function quite differently from that of the rod system, in which several rods are connected to the same bipolar cell. The pure cone system cannot have spatial summation, whereas in the rod system a large taint patch of light may stimulate a whole group of rods so that their individual responses can be added together until they reach the threshold necessary to send an impulse through one nerve fiber. This system can respond to light of lower intensity than can the cone system, even though the sensitivity of the single rods might be assumed to be no greater than that of the single cones. Hence those areas which have single receptors connected to one nerve fiber have great discrimination in detail, whereas the areas in which there is considerable spatial summation have lower thresholds for the detection of light, and are especially useful for the detection of movement of objects in the visual field.

The remainder of the macula is composed of a combination of cones and a very few rods. This section of the retina is capable of resolving very fine detail. Proceeding outward from the foveal-rnacular area more and more rods are present and at the same time fewer and fewer cones until the extreme periphery of the retina contains about 10 rods for every cone. In the foveal area each cone is synaptically connected to a single ganglion cell. In the rod system, several rods are connected to the same ganglion cell.

The retina is unlike a photographic plate in that its properties are not fixed. The sensitivity of the photo graphic plate cannot be immediately altered to meet the requirements of different intensities of illumination, Whereas the retina within a relatively short time can adapt itself to changes in brightness level. Another quality of the retina in which it dilfers from a photographic plate is the response in certain nerve fibers when the light is turned off. This response is governed by the intensity of the preceding illumination and the duration or" the stimulus. Consequently each region is affected by what is going on in surrounding areas so that the eifects of stimulation are not strictly localized in extent. The activity of the retina depends, therefore, partly upon changes due to previous stimulation and partly upon activities taking place in other regions of the retina at the time of stimulation. These effects are known as temporal and spatial induction.

There are three principal layers of nerve cells in the retina of the eye (see FIGURES i4, 15, 16 and 19); the rods and cones, which are the receptors, the bipolar cells (1st order neuron) which mediate the B and C response below, and the ganglion cells (2nd order neuron), which fibers travel up the optic nerve to connect with the 3rd order neuron in the visual centers of the brain (FTGURE 19). These nerve cells are also joined to one another in a variety of combinations of cross connections. Thus the retina is a true nerve center, no less complex than other parts of the central nervous system. The retinal fibers react to the light stimulus.

A stimulus is any energy that elicits a response from the nerve fiber. The response is in the nature of an electrical discharge, which is transformed into a nerve message. Each nerve responds in a particular manner to a stimulus and never gives any other kind of response, regardless of the condition of stimulation or the adaptation of the fiber for the stimulus.

There are three distinct types of responses of dilferent fibers in the same eye. He shall identify these responses as A, B, and C.

Response A.The fiber responds with a rapid burst of impulses when the light is turned on, soon dies down to a steady slower discharge. There is no response to cessation of illumination in this fiber.

Response B.The fiber gives the same as the previous one but the impulse stops immediately although the light is kept on. The B fibers respond to very slight changes in intensity, the greater the change the more marked the response. The B fiber is very sensitive to any movement of the retinal image.

Response C.The fiber gives no response whatever when the light is turned on, or through the whole duration of illumination, but when the light is turned of, there is a rapid burst of impulses. It is the C response that is utilized for spatial induction with the centroscope. The discharge of impulses in the C fibers signalling cessation of stimulation must not be held to imply that these fibers are actively responding to darkness or the absence of light, but rather some process is developing in the retina during illumination, which is identical with inhibition, stopping the discharge in these fibers upon re-illumination.

The B and C types of responses occur in the bipolar and ganglionic structures which are interposed between the rods and cones. In order for the C response to be given oil, the receptor must be prepared for this response by the effect of the light stimulus; for only if previously prepared by the stimulus can they function when it is removed. Thus it is, that the peripheral retina is stimulated for a definite period of time with high intensity of illumination with the centroscope, to prepare it for the inhibition immediately following the exposure (FIGURES l0 and 18). It is not uncommon to find that the retina, if exposed for seconds to the centroscope light, will retain this inhibitory response for several minutes. The afterimage formed by the bleaching can frequently be recalled hours afterwards, both positive and negative afterimages.

At all levels of illumination between complete light adaptation and complete dark adaptation, the retina makes every effort to come into equilibrium with any change of illumination. Below the level of 0.1 meter candle, the rods (peripheral retina) alone function. Above this level, the cones begin to function (fovea). As the illumination increases still further, the complete bleaching of visual purple stops rod function entirely and vision at high levels of illumination is due solely to cone function, which is the case after centroscope stimulation. At intermediate levels, both cones and rods are active.

Light which is absorbed affects a photochemical reaction in the retina. This reaction is the primary and probably the least complicated part of transforming light energy into a nerve impulse. The substance in the retina having the property of absorbing portions of the visible spectrum is called a pigment. A photosensitive pigment is present in the rods and hence confined to the peripheral retina. It is called rhodopsin or visual purple. It is not definitely known to applicant whether or not it is present in the cones of the foveal area of the retina. The photochemical substance in the cones has not been identified.

Light has the effect of bleaching the visual purple to visual white. In the absence of light, visual purple is reformed. When an eye is subjected to continuous illumination, the visual purple is bleached by the light and is also being reformed, thus striking a balance between the rate of bleaching and the rate of regeneration. This steady state of balance between catalysis and synthesis remains as long as the illumination remains unchanged. Thus the retina, by chemical and possibly electro-physiological changes, can adapt itself to meet the requirements of different intensities of light. Also, each region of the retina is affected by what occurs in surrounding areas, thereby modifying or enhancing the local stimulation. When the activity of the retina is affected by changes due to previous photic stimulation it is called temporal induction, a time value; if affected by activities taking place in other regions of the retina, it is called spatial induction, a simulataneity of spatial perception. Centroptics utilizes both temporal and spatial induction for its effectivcness.

APTERIMAGES Afterimages are the transient, fluctuating sensations which occur after the primary image has disappeared. They vary according to the manner in which the retina is stimulated. When the retina is stimulated by a bright light, the primary image of the light is seen. If the eyes are closed following this exposure, an image of the light of the same shape will atpear, an afterimage. A positive afterimage is one which has the same color and shape as the stimulating light. It is easily seen with the eyes closed, or in a darkened room with the eyes open, or with the eyes directed at a dark background. A negative afterimage has the same form as the stimulating light, but is of a different color from that of the stimulus. A secondary light stimulus, a light colored wall for example, is usually needed for its elicitation. When a light stimulus produces a positive afterimage, no other stimulus of a like nature can elicit a response from the exposed area of the retina because of the inhibition produced by the afterimage. It does, however, react to stimuli of an opposite kind, a secondary stimulus, thereby eliciting an afterimage, usually opposite to the first afterimage (positive afterimage, than negative). Afterimages may remain for seconds only, or recalled hours later. A positive afterimage is easier to obtain and retain than a negative afterimage.

The negative afterimage which originates from centroscope stimulation has many gradations of color, or it may be negative and positive simultaneously; the central area of the afterirnage may be positive, the outer, surrounding area negative, varying from light green, blue, orange, red to purple. A normal negative afterimage is dark purple when the stimulating light is that of the white light of the centroscope (FIGURES 10 and 18). Before reaching the dark purple stage it may be yellow, green, orange, red, blue, then purple.

As stated before, afterimages result from photochemical processes in the retina. However, since afterimages can be conditioned with practice, it cannot be denied naent of her vision was doubtful.

that higher sensory areas may influence their intensity and duration by the reinforcement-of repetition. The photochemical process is the Beta adaptation of the retina to photic stimulation and is confined exactly tothe retinal area stimulated, eventhough a small portion ofthe retina has been stimulated. The Alpha sensitivity applies to the entire retina even though only a small portion ofthe retina has been stimulated. This process represents the ervous system and is quicker in its response than'the Beta response. When stimulated with the centroscope, the Alpha adaptation presumablyreintorces the Beta response of the retina. Though the central processes may exert inhibitory influences on afterirnages,-it is certain they do not take their origin in the higher centers. (Crai'd W Origin oiVisual After-Images, Nature, London, 154: 512, -l940.-)

Binocular fixation can result only from normal monocular fixation in both eyes. Poor monocular fixation may result from low visual acuity or "disease of the-retina in the'foveal area. Rarely does it occur as aresult of impaired development of the proprioceptive mechanism. The eye may wander rather than be fixated or directed to the object so that the image does not fall on the fovea. This is spoken of as eccentric fixation. The centroscope is primarily for the purpose of (1.) restoring monocular central fixation, then (2) binocular central fixation.

USAGES (1) Amblyopia (Loss of Vision) in One or Both Eyes From Various Causes (A) Amblyopia ex anopsia.lt has been amply dem onstrated that the use of the centroscope is highly effective in restoring vision in an eye where the cause of the loss is due to disuse or non-function of the eye. Children with this kind of amblyopia will commonly demonstrate an improvement of one line (Snellen chart) of vision after a Week of home therapy on the centroscope and continue to do this until normal visionhas been achieved. Older children and, adults have shown the same improvement, though it may not be accomplished as quickly. ll/iany former patients with poor vision who were treated with conventional therapy and had. made little or no improvement, madegdramatic progress with centroscope therapy.

(B) Amblyopia with aphakia.--The children and adults who had cataracts surgically removed andWho had reduced visual acuity with their corrective lenses, improved their visionwith-centroscope therapy. With "the adults, the visual, improvement was notthe objective of the therapy, but to restore central fixation to overcome an annoying andinsuperable diplopia. The centroscope therapy did in fact overcome the diplopia restoring the central fixation with the added benefit of improving the vision. V

tientswithhealed retinal pathology effecting the, central vision improved the visual acuity with-centroscope therapy. One patient with a'healed central retinitis, asked to be put on centroscope therapy asan experiment, after having been toldit was not indicated and thatimprove- Shedid intact improve her vision from 20/ 70- to 20/25 for near and distance, after twomonths of work with the centroscope. The Waviness of vision she experienced with this eye also disappeared and the images appeared normal in outline.

(D) Physiology ofiamblyopia ex anopsia.-I mage inhibition of one eye occurs in patients'with'strabismusyin an eye that deviates-in, out, up or down to avoiddiplopia,

thatis, seeing double (FIGURE 8). This-sensory phenomenon occurs in the higher visual centers and is a compensatory-mechanism whereby the brain refuses to recognize the messagefrom one eye, when this eye deviates from its normal straight position or fusion position. Image inhibition and rejection in thedeviating hibited when the. centroscope is held vertically and the eye exposed while fixating centrally on the center dot (FIGS. 1 and 7). The foveal area F must ofnecessity accept the image since the inhibited area between F and P cannot function. Thus, normal acceptance of. stimuli ,to the foveal area is established, and a normal response pattern can then be conditioned with repeated centroscope stimulus.

(2) Anomalous Retinal Correspondence This condition is variously called anomalous sensorial relationship, abnormal retinal correspondence, anomalous spatial interpretation.

Thereare two aspects to vision; the motor and sensory.

The motor part is the looking,thernuscles moving the eyes for proper image reception on the foveas. The sensory is the seeing, or the interpretation of what we see and where it is located in space. The sensory seeing part of vision is in a developmental and learning stage presumably, until the age of 7 years, when it has reached maturity, and fully conditioned.

-When an eye crosses orgets out of alignment with the other eye, it is called a motor anomaly. Thus, the sensory alignment does not fit into this new eye position and consequently makes an adaptation to get rid or the double vision. Thus, the first adaptation is the inhibition of the image formed on the stimulated peripheral retinal receptor and also the rejection of the different image formed on the. foveal area of this eye. After a period of time, a permanent re-alignment of the sensory maladjustment has been so conditioned with usage, thus introducing a second adaptation, the change in' thespatial or direction values in the deviated eye to correspond to the deviated position of the eye rather than the straight position. This anomalousinterpretation does, not occur-when only one eye is being used. and the other eye is covered, but oc curs only when the two eyes are seeingas a single unit. The. fixating eyewill interpret .normally'the location of theooject in. space ofthe image formed on the stimulated retinal receptor, which would be the fovea. However, the image of thesame object is not formed on the fovea of the deviated eye, but on a peripheral, retinal receptor, which vhas a diiierentspatial or direction value from that of the fovea, namely the straight head direction. With the anomalous adaptation, the stimulatedperipheral retinal area may now have the same spatial value as the fovea of the fixating eye, that is, the straight ahead direction. It is this peripheral retinalarea that is inhibited with the centroscope, thereby forcing fixation with the central area which is not inhibited. The. after-images also become .a frame of reference to, maintain central fixation.

(3) Development or Restoration of; Fusion When images fall on corresponding retinal areas they are fused into a singlemental impression and projected mentally to the same place in space. It has been assumedthat there is a center in the brain where fusion of the two-images occurs, in the same way one speaks of a center .for speech. We doknow, however, that fusion halves of a single organ, the cyclopean eye (FIGURE 19).

The fovea of, this cyclopean eyegives us our egocentric localization with respect to the visual world around. us.

Frequently, in subjects with strabismus, it is found there is no fusion. Only one eye is used, the other eye sends no visual message to the brain and if it does, it is destroyed or rejected and not registered as a visual message." Many of these subjects never had fusion or binocular vision at birth, so we assume. Orthoptics, or visual training does not alter this situation for them. However, the use of the centroscope has definitely established fusion in subjects where the techniques were properly employed.

It is presumed the use of the centroscope aids to establish fusion by removing the previous stumbling blocks, namely, amblyopia suppression and anomalous retinal correspondence.

(4) To Reduce Completely Eliminate the Deviatcd Position of One Eye in Slrabismus Because of the effects of the centroscope on the preceding conditions, namely, amblyopia, suppression and anomalous retinal correspondence, a strabismic eye (crossed, divergent, or vertically divergent) will frequently straighten completely and remain straight if proper follow-up orthoptic care is given. A few will do so without follow-up orthoptic care. Those cases which do not straighten completely will have some reduction in the amount of the deviation. This may be of significance to the surgeon who is contemplating surgery on a strabismic patient; it gives him information as to the type and amount of surgery to be done since this differentiates the amount of deviation that is functional correctable with the centroscope, and that which is mechanical or muscular, which of course needs surgical measures for its correction.

In addition to the above-described usages, the present invention may be employed to eliminate light sensitivity and to make uncomfortable eyes comfortable, especially those with presbyopia and where a convergence insufficiency exists.

TECHNIQUES The centroscope can be held by hand in front of either eye, in any position; vertically, horizontally or obliquely, or it can be fanned in front of the eye to form segments of a circle. It is held in one position, 6 to 12 inches from the eye for a period of to 60 seconds, followed by a like procedure with the light held in another position in front of the same eye. For example, let us assume it is used in the treatment of an amblyopic left eye. The light is held vertically at 8 inches from the eye for seconds, the eye looking at the red dot 24. The light is then changed to the horizontal position and the eye views the central dot at 8 inches for seconds. The horizontal viewing is longer than the vertical since it takes more stimulus to break down the suppression in the retinal areas lying horizontal to the fovea. The patient then closes his eyes and soon the positive afterimages are perceived (FIGURE 9). Perhaps he will see only one or both horizontal lines 21b, or only the vertical lines 21a, or he will see only one vertical and one horizontal line. Finally, he will see the two vertical and two horizontal lines with a space 23a in the center. The entire afterimage may be perceived only momentarily, then completely or partially fade out. When he can see the cross with the space 23a in the center with his eyes closed, he then opens his eyes and fixates a small letter M on a light colored wall about four feet distant. Gradually the negative afterimages appear, or they may continue to be positive as he may not be able to perceive a negative afterimage. In the case of anomalous retinal correspondence, he can not locate the letter M in the middle space 23a, but somewhere along the lateral or vertical afterimage, or even obliquely, at a 2, 4, 8 or 10 oclock position. As the negative afterimage becomes stronger and can be maintained for several minutes, from 4 to 20 feet distant from the fixated letter, then both eyes are stimulated.

In the treatment of image suppression let us assume the condition of right esotropia with foveal and macular suppression or image inhibition, 20/40 vision right eye, 20/40 left eye. The left eye remains covered during the entire procedure. Stimulate the right eye only with the centroscope as follows:

Centroscope vertical, 60 seconds, light 6 inches from eye.

Centroscope horizontal, 60 seconds, light 6 inches from eye.

Do this 3 times daily, twice in succession each time, a total of 6 exposures.

Following the exposure, the patient sees an afterirnage of cross with space 23:: as long as possible afterwards, while viewing a letter on a light colored wall about 4 feet distant (FIGURE 9). A letter about one-half inch overall size is preferable since it approximates normal visual acuity as measured at 20 feet. He then opens and closes his eyes alternately for IO-second periods. The afterirnage should be positive with the eyes closed, negative with the eyes open. With the eyes closed, the cross will be seen white or yellow, with a space in the center, the space representing the protected central foveal area. As the right eye fixates the letter M on the wall, the cross will be seen in a gradation of color until it appears as dark purple. The letter must be seen as cl arly as possible, indicating foveal fixation. During the eyes open period, the patient backs off one stop, until he reaches a distance of 20 feet from the letter, continuing to see the negative afterimages with the letter in the central space and seeing the letter clearly. When the afterimages begin to fade, or he can no longer see the four images simultaneously, the entire procedure is repeated.

The above stated technique is the one employed at the present time to eliminate image inhibition and to establish central fixation. It varies according to the individual case, the amount of suppression, visual loss and eccentricity of fixation.

The treatment is confined to the retina of the deviating eye until: (1) the vision in the deviating eye has improved to 20/30 or better, and (2) the deviating eye can hold foveal fixation with the normal eye uncovered. Then both eyes are stimulated: The normal left eye for 40 seconds with the centroscope vertical; the deviating right eye for 60 seconds with the centroscope horizontal. Following this stimulation the patient, with eyes closed, sees the afterimage shown in FIGURE 9. With eyes open and if no suppression is present, he sees two letters on the wall, the letter seen by the right eye having the horizontal afterimages shown in FIGURE 12, the letter seen by the left eye having the vertical afterimages shown in FIGURE 11. As he straightens his eyes, the letters move closer together and when fixation with the two foveas has moved the deviating eye to the center and the eyes are straight, the two images of the letter will fuse and the 4 afterimages form a cross around it as shown in FIGURE 10. During this procedure also, he opens and closes his eyes alternately for 10-second periods. During the eyes open period, he covers and uncovers the normal left eye 3 times to insure steady, foveal fixation with the right eye. When he fixates the right eye, the left eye may deviate and if both eyes are seeing and not suppressing he sees two images of the letter on the wall.

Suppression is the precursor of amblyopia, and loss of fusion. All cases of strabismus must necessarily establish suppression to avoid diplopia. Suppression and/or amblyopia requires the same centroptic technique. By eliminating suppression and establishing a normal stimulus-response pattern, it is possible to: (1) Develop or restore fusion, (2) straighten the eyes in strabismus, (3) make uncomfortable eyes comfortable, and (4) eliminate light sensitivity or photophobia due to suppression.

angle, double vision results.

When anomalous retinal correspondence exists there is a sensory as well as motor change and therefore the sensory adaptation is interpreted as conforming with the changed eye posture. This means that the direction sign or spatial localization of the retinal elements in the deviated eye is changed to function as if the eye were straight. Therefore, all stimulous with the centroscope is given to the deviating eye only until the anomalous sensory adaptation is eliminated and a normal spatial localization established. The deviating eye remains occluded at all other times. in this way the usage pattern of the deviated eye is broken by dis-use. Exposure to the centroscope stimulates the'fovea to a correct response and inhibits the peripheral retinal area in the same eye from responding in the old erroneous manner, The after images assist in this maneuver by acting as a frame of reference and wiping the slate-clean as it were, on the area on which it is formed, so that the abnormal response pattern is inoperable. The inhibition caused by the bleaching of the visual purple in'the peripheral area makes possible spatial induction. Inhibition in the peripheral area and'stimulates the eye to turn to the center for central and therefore foveal fixation.

In the treatment of anomalous retinal correspondence, let us assume a case of esotropia of 15, right eye, for centroscope therapy, and with vision 20/30 in right eye, and 20/20 in left eye. When, by means of instrumentation, the images are placed on the foveas at 15 A lesser angle or would bring the images together for the patient. The images, however, would not be imaged on corresponding retinal elements, i.e., the two foveas. The patient would be fixating with the fovea of one eye and a peripheral area of the other eye. The right eye remains occluded at all times except when receiving the centroscope stimulation. During centroscope stimulation the left eye is oceluded and the right-eye stimulated, first with the centroscope in the vertical position for 60 seconds, then'with the centroscope in the horizontal for 60 seconds. When he can elicit the afterimages, positively, in the form of a cross with the central space 23a, then he endeavors to see the negative afterimage with the central space 23a, as well as to see the small letter M on the wall in that central space. When he can accomplish this and the visual acuity has improved to 20/25 or better, and the foveal suppression has begun to break down, then each eye is stimulated separately, not simultaneously, always keeping the non-stimulated eye covered. When the letter M is correctly centered in the middle space 230 of the cross, then both eyes are stimulated and remain uncovered while viewing the negative afterimages. The centroscope stimulation is now given as follows: Left eye first, light vertical, exposure time 50 seconds. Right eye last, light horizontal, exposure time 60 seconds. Then the afterimages are perceived with the eyes closed. The image lines may form a cross or they may be separated in a crossed position; the right horizontal images to the left of the vertical images seen by the left eye. Also, the letter M is seen double, one with the vertical, one with the horizontal afterimage lines. When the two images of the letter become fused in the middlespace and the 4 afterimage lines form a cross around the central space, then the anomalous retinal correspondence is changing to normal. The normal and anomalous may remain simultaneously for a time. During this adjustment period the deviated eye may see double; a clear image is on the foveal and a dimmer image on the peripheral retinal area formerly associated with the foveal area of the normal eye. As therapy proceeds, the dim mer peripheral image gradually yields and disappears, leaving the foveal image to remain associated and fused with the foveal image in the other eye. This is Normal Retinal Correspondence and a first goal of progress in therapy for anomalous retinal correspondence.

In the drawings andspecification, preferred embodii4 ments of the invention have been disclosed and although specific terms are employed, they are used in a generic sense and not-intended for the purpose of limitation, the scope of the invention being set forth in the following claims.

I claim:

1. Viewing apparatus for therapeutically treating the human eye comprising: an opaque housing having a target opening therein for substantial optical alinement with the centralfoveal'macular area of the eye retina, a light source of high intensity mounted'in said housing, a dark adaptive filter covering said opening and adapted to transmit a beam of red light rays containing approximately from 10 to 15 percent of the red portion of the visible spectrum from said source to said central fovealmacular area and to filter the other light rays of the visible spectrum from said beam, a second opening in said housing spaced adjacently from said first opening, said second opening so constructed and arranged to direct a beam of unfiltered light from said source onto a peripheral retinal area of the eye, and means insaid space between the openings for shielding an area of the eye retina adja cent the central foveal-macular area thereof from said high intensity light source.

2. Viewing apparatus for therapeutically treating the human eye comprising: an opaque housing, a light source of high intensity mounted in said housing, means optically alinable with the central foveal-macular area of the eye retina for transmitting a beam of red lightrays containing approximately from 10 to 15 percent of the red portion of the visible spectrum fromsaid source onto said area, means for filtering the other light rays of the visible spectrum from said beam, means for directing a beam of unfiltered light from said source onto a peripheral retinal area of the eye, and means for shielding an area of the retina intermediate said peripheral and central foveal-macular areas from said high intensity light source.

3. That method of therapeutically treating the human eye which comprises the concurrent steps of: exposing the central foveal-macular area of the eye retina to red light rays containing approximately from 10 to 15 percent of the red portion of the visible spectrum to provide a fixation stimulus for the area, exposing to light of fixed intensity selected peripheral retinal areas-angularly positioned respectively on lines extending radially from the foveal-rnacular area, the intensity of said light being sufficient for maximum inhibition of fixation and spatial orientation in said selected areas, and shielding from said inhibiting light an area surrounding the exposed fovealmacular area and lying radially inwardly from the exposed selected retinal areas.

4. That method of therapeutically treating the human eye which comprises the concurrent steps of: exposing the central foveal-macular area of the eye retina to a beam transmitting approximately from 10 to 15 percent light to provide a fixation stimulus for the area, exposing to light of fixed intensity selected peripheral retinal areas angularly positioned respectively on lines extending radially from the foveal-macular area, the intensity of said light being sufiicient for maximum inhibition of fixation and spatial orientation in said selected areas, and shielding from said inhibiting light an area surrounding the exposed foveal-macular area and lying radially inwardly from the exposed selected retinal areas.

5. That method of therapeutically treating the human eye which comprises the steps of: exposing to light of high intensity selected peripheral retinal areas of the eye located in predetermined positions relative to the fovealmacular area there of to thereby bleach the visual purple of the selected areas to a visual white and to inhibit them from re-stimulation, providing a fixation light stimulus to while sparing the foveal-macular area from said inhibition and bleaching to cause the latter area to become dark adapted, and subsequently exposing said inhibited peripheral retinal areas and said dark adapted foveal-macular 15 areas to a secondary light stimulus to thereby elicit in space negative afterirnagcs corresponding to the inhibited areas and at said predetermined positions.

6. That method of therapeutically treating the human eye which comprises the concurrent steps of: light adapting selected reference areas of the retinal lying radially of and defining the location of the foveal-rnacular area of the eye, dark adapting the foveal-macular area While supplying the latter with a fixation stimulus of filtered light, and shielding from light adaptation an area surrounding the foveal-macular area and lying between the latter area and the selected reference areas, and subsequently eliciting afterimages in space from said reference areas defining the location of the foveal-macular area of the eye.

7. The method as set forth in claim 6 wherein said first step comprises light adapting at least one area of the retina positioned horizontally and radially of the foveal-macular area of the eye, and light adapting at least one second area of the retina positioned vertically and radically of the foveal-rnacular area.

8. That method of therapeutically treating the human eye which comprises the concurrent steps of: stimulating the fovcal-macular area of the eye, and dark, adapting it, light adapting peripheral retinal areas defining the location of the foveal-macular area with light of sufiicient intensity for maximum inhibition of fixation and spatial orientation of said peripheral area, and shielding from said inhibiting light an area surrounding the foveal-macular area and lying between the latter area and said Peripheral retinal areas, and subsequently eliciting afterimages from said light adapted retinal areas defining in space the location of the foveal-rnacular area.

9. Viewing apparatus for therapeutically treating the human eye comprising: a housing having an exterior opaque wall surface, a high intensity light source mounted within said housing, the opaque surfaced wall portion of said housing having an opening therethrough with the exterior end of the latter surrounded by said opaque surface, and means for transmitting through said opening a beam containing from 10 to percent light from said source, said housing having a plurality of second openings therein spaced radially from said first opening and operable concurrently with said first-named means to transmit respectively a plurality of unfiltered light beams from said source, and said opaque surface surrounding said first opening being alined with said source to substantially interrupt light transmission along a tubular path separating the first beam from the second beams, said first and second light beams occupying fixed relative positions simultaneously alinable respectively with the fovealmacular area of the eye on one hand, and with selected peripheral retinal areas of the eye spaced from and lyingradially of the foveal-macular area on the other hand.

10. Viewing apparatus as defined in claim 9 wherein said second openings comprise a pair of elongated slots longitudinally alined with said first opening, and wherein said light source comprises an elongated filament extending substantially parallel to said alined slots and openmg.

11. That method of therapeutically treating the human eye which comprises the steps of: imparting a fixation light stimulus to the central foveal-macular area of the eye while sparing it from inhibition and bleaching, concurrently exposing to light selected peripheral retinal reference areas defining the location of said foveal-macular area, the intensity of said light being sufiieient to impart maximum inhibition of fixation and spatial orientation in the selected areas, and then exposing said inhibited reference areas to a secondary light stimulus to elicit in space afterimages of similar configurations.

12. That method of therapeutically treating the human eye which comprises the concurrent steps of: light adapting at least a portion of the peripheral retinal area defining the location of the foveal-macular area of the eye, dark adapting the foveal-macular retinal area of the eye, and subjecting the central portion of the fovealmacular area to a fixating light stimulus whereby the dark adapted area will be inducted to remain in a fixed position during said light adapting and dark adapting steps, and the subsequent step of exposing said retinal portion to a secondary light stimulus to elicit afterirnages in space corresponding to the light adapted portion defining the location of the foveal-macular area of the eye.

References Cited by the Examiner UNITED STATES PATENTS 2,098,990 11/37 Newton 128-496 2,239,164 4/41 Wigelsworth 128-2X 2,803,246 8/57 Lange "128-765 2,930,379 3/60 Dopp 128-396 2,999,422 9/61 Papritz 3,036,568 5/62 Stark 128-2 OTHER REFERENCES Glasser: Medical Physics, 1944, pages 265-274, 1658- 1666. Medical Physics, 1960, Vol. 3 pages 601-603.

A. J. of Ophthalmology, October 1961, pages 474-479.

LOUIS R. PRINCE, Primary Examiner.

RICHARD J HOFFMAN, Examiner.

Claims

1. VIEWING APPARATUS FOR THERAPEUTICALLY TREATING THE HUMAN EYE COMPRISING: AN OPAQUE HOUSING HAVING A TARGET OPENING THEREIN FOR SUBSTANTIAL OPTICAL ALINEMENT WITH THE CENTRAL FOVEAL-MACULAR AREA OF THE EYE RETINA, A LIGHT SOURCE OF HIGH INTENSITY MOUNTED IN SAID HOUSING, A DARK ADAPTIVE FILTER COVERING SAID OPENING AND ADAPTED TO TRANSMIT A BEAM OF RED LIGHT RAYS CONTAINING APPROXIMATELY FROM 10 TO 15 PERCENT OF THE RED PORTION OF THE VISIBLE SPECTRUM FROM SAID SOURCE TO SAID CENTRAL FOVEALMASCULAR AREA AND TO FILTER THE OTHER LIGHT RAYS OF THE VISIBLE SPECTRUM FROM SAID BEAM, A SECOND OPENING IN SAID HOUSING SPACED ADJACENTLY FROM SAID FIRST OPENING, SAID SECOND OPENING SO CONSTRUCTED AND ARRANGED TO DIRECT A BEAM OF UNFILTERED LIGHT FROM SAID SOURCE ONTO A PERIPHERAL