US2262217A - Apparatus for orthoptic training purposes - Google Patents

Description

Nov. 11, 1941. LE ROY WOTTRING APPARATUS FOR ORTHOPTIC TRAINING PURPOSES 2 Sheets-Shee 1 Filed Nov. 16, 1938 ww V,

INVEJVTOR: Le Roy l Va/frmy.

ATTORNEY Nov; 11, 1941. LE ROY WOTTRING 2,262,217

APPARATUS FOR ORTHOPTIC TRAINING PURPQSES Filed NOV. 16, 1938 2 Sheets-Sheet 2 I l1 VVE NTOR.

Le/Poy Waffr/ng.

5 ATTORNIEYZ Patented Nov. 11, 1941 UNITED STATES PATENT OFFICE APPARATUS FOR ORTHOPTIC TRAINING PURPOSES a corporation of Ohio Application November 16, 1938, Serial No. 240,865

11 Claims.

My invention relates to apparatus for orthoptic training purposes. It has to do with apparatus for directing the exercising of the muscles of the eyes to improve the tonicity thereof and to correct conditions and habits of improper innervation. More specifically, it deals with such apparatus which is particularly useful for the treatment of suppression, suspension, and anomalies of innervation to the extrinsic and intrinsic muscles.

In my Patent No. 2,091,173 on Apparatus for orthoptic training purposes, which issued August 24, 1937, I described an apparatus for exercising the eyes which consisted mainly of a pair of targets adapted to be fused by the patient and means for moving such targets in a rotary path without overturning and without rocking relative to the line of vision. Also, as disclosed in said patent, I provided a separate light for illuminating each target and I also provided means for flashing each light so that each target would be alternately illuminated and without illumination during selected periods. The means for flashing the lights used for illuminating the target was particularly useful in the treatment of suppression and suspension and for stimulation of accommodation.

When using the instrument disclosed in said patent in treating cases of amblyopia or suppression, the flashing is used to stimulate the suppressing or suspending eye and to correct anomalies of accommodation. Although the instrument disclosed in my prior patent has many advantages and has been widely adopted for orthoptic training purposes, I have discoveredthatit is desirable to provide an improved arrangement for illuminating the targets and for stimulating vision. I have discovered that it is desirable to have the eyes light-adapted at all times and to stimulate or inhibit accommodation While still maintaining light-adaptation rather than to interrupt illumination of the targets in the manner disclosed in said patent and thereby destroy light-adaptation.

The main object of my invention is to provide an apparatus for orthopic training purposes which is of such a nature that vision is stimulated by the use of illuminated targets upon which the eyes iiXate, the apparatus being of such a nature that the eyes may be kept light-adapted constantly.

The apparatus which I use is in the main of a structure practically identical to that disclosed in my prior Patent No. 2,091,173. However, I provide a different and improved arrangement of the targets and the means for illuminating the targets, for stimulating or inhibiting accommodation. This arrangement is such that accommodation is stimulated or inhibited by changing fixation from secondary to primary targets, the primary and secondary targets being illuminated alternately andthereby keeping the eyes lightadapted constantly.

Various other objects and advantages will be apparent from the following description.

The apparatus which I preferably use is illustrated in the accompanying drawings wherein similar characters of reference designate corresponding parts and wherein:

Figure l is a perspective view of an orthoptic training instrument made in accordance with the principles of my invention.

Figure 2 is a longitudinal section taken through one of the tubes that is movably mounted on the instrument and carries the primary and secondary targets, target-illuminating means and associated elements.

Figure 3 is a side elevation of the instrument shown in Figure 1.

Figure 4 is a detail in perspective illustrating the outer end of one of the tubes and showing how the eye movements may be observed by the practitioner.

Figure 5 is a view showing the shape of the targets which I preferably employ.

Figure 6 is a diagrammatic illustration of the electrical circuits employed in connection with the instrument.

Figure 7 is a side elevation of a tube of the type shown on the instrument in Figure 1 but provided with additional means whereby the eye movements of the patient may be observed.

With reference to the drawings and particularly to Figures 1 and 3 I have illustrated an instrument which, with the exception of the target arrangement and target-illuminating means, is practically identical with the instrument disclosed in my Patent No. 2,091,173.

As described in my said patent, the instrument comprises a base I which is of the construction shown and which carries a casing or housing 4. The housing 4 carries the operating mechanism of the machine which is practically identical with that described in my prior patent and which therefore need not be described herein. At the front and outside of the housing 4 a stage 20 is mounted in such a manner that it may be moved in a rotary path about a center, as described in said patent. This rotary path may be varied and the speed of the rotary movement may be a suitable image formed thereon.

positively controlled. Also, themovement of the stage is automatically reversed at intervals. All of the mechanism for accomplishing these different operations is disclosed in detail in my said prior patent.

In the instrument disclosed in my prior patent, the targets to be viewed by the patient were mounted directly on the stage 20, base-out prisms were supported on a supporting arm I! carried bythe base I, and a septum was provided to insure that each eye would view one target only. However, in the instrument disclosed in this present application the targets are arranged and supported in a difierent manner and the septum is not employed. Instead two separate tubes 32 are employed which are mounted in the manner illustrated in the drawings. The inner end of each tube is supported on the stage 2!] while the outer end of each tube is supported on the supporting arm I I.

Each tube 32 has a base-out prism lens I9 secured in its forward'end. At a point directly behind the lens I9, the tube 32 is provided with an upwardly projecting tubular socket member I50. This socket member I5!) is open at both its upper and lower ends and its lower end communicates with. the interior of the tube 32. Directly below this socket I50 and directly behind the lens I9 is supported a transparent member Illa. This member. I9a is supported at an angle of approximately 45 degrees relative to the axis of the tube .32. In front of the lens I9 a socket I92) is provided for receiving auxiliary plus or minus spherical lenses which may be needed for some patients.

The socket I50 is adapted to receive a removable secondary target receiving member I5 II which is of tubular form and has a reduced lower portion that fits intothe socket. The upper enlarged portion of member I5] is provided with a horizontally disposed substantially semi-circular slot I52 adapted to receive a secondary target 24a. This target 24a is made of translucent material having a suitable image formed therein and is preferably of the shape illustrated in Fig- 'ure 5. It comprises a semicircular lower portion 24b and an upper substantially rectangular portion 240 with a shoulder Md being formed to limit inward movement of the target when inserted in the slot I52. The portion 241) has the same radius as the interior of the upper portion of. member I5l. The portion 280 will project outwardly from member I5l. By gripping portion 240 with the fingers the portion Mb may be rotated relative to the axis of the member I5I.

'32 a plurality of substantially semicircular slots 155 are formed therein at longitudinally spaced intervals. Any one of these slots is adapted to receive a primary target 24s. The target 246 is preferably made of translucent material and has sameshape as target 24a but is larger. The target will be maintained in vertical position after tube 32 and is preferably of the same curvature 1 It is of the as the tube. It may be rocked relative to the axis of the tube 32 in the same manner described with reference to target 2 3a. It will be apparent that the distance of the primary target from the lens I9 may be varied by positioning the target in different slots. This variation of the positions of the target will be equivalent to using plus and minus auxiliary lenses in association with the lens I9. A calibrated scale I55a may be provided adjacent the slots I55 which may be calibrated in quarter diopters to indicate the position of the target.

The rear end of each tube 32 is provided with a light housing I53. This housing has a light socket 39 secured to the side thereof which receives a removable light bulb 33. The bulb 33 is horizontally disposed. The rear end, the sides, the top and the bottom of the housing I55 are closed. The forward end thereof is open and communicates with the tube 32. In front of the bulb 38 in the housing 56 a plurality of sockets I57 are provided for receiving one or more square color filters I53. A light shield I59 pivoted to the top of housing I56 will normally cover the filter-receiving sockets I57. This color filter may be provided for a purpose which will be explained hereinafter. It will be apparent that light from the bulb 38 will illuminate the target 246 in the manner illustrated in Figure 2. If the filter I53 is in the position indicated, this light will first pass through the filter.

Each of the tubes 32 has its forward end universally connected to the supporting arm I! and its rear end universally connected to the stage 29. For connecting theforward end of each tube to the arm I! a bracket 33 is provided. The forward end of the tube is pivotally connected to the upper end of bracket 33 as at 34. The lower portion of the bracket 33 is provided with a pin which fits into a socket i'la provided on the upper end of the arm I! and the pin is free to rotate in the socket. The pin may be merely slipped into or out of the socket in order to mount the forward end of the tube 32 on the support IT or to remove it therefrom. Thus, it will be apparent that the forward end of the tube 32 is connected to the support I! in such a manner that it may move universally relative thereto.

The rear end of the tube 32 is universally connected to the stage 29 by the structure which I will now describe. The connection is made to a member 24 which is vertically adjustable on a plate member or strip 23 carried by the stage 20. The member 23 is mounted on the stage in exactly the same manner as the corresponding member disclosed in my prior patent. Also, the member 24 is mounted on the strip 23 in practically the same manner as the card-holding member 24 of my patent. Movement of the members 23 towards and away from each other is controlled by means of the knob 29, as described in my patent.

Each member 23 carries a forwardly projecting lug 23a. The upper portion of a screw 25 is threaded through this lug. The lower portion of the screw is threaded through a forwardly projecting arm 35a which has its rear end secured to the lower portion of member 24. By rotating the screw 25, the member 24 and the arm 35a carried thereby may be adjusted vertically relative to member 23. A calibrated scale 24 is provided on member 23 to indicate the vertical position of member 24 on member 23. The forward portion of member 35a has a slide 3519 of semicircular cross-section formed thereon.

This slide is adapted to receive a ball portion 31b formed on the lower end of a pin 31a depending from the rear end of tube 32 to which it is secured. When the stage 20 is rotated, the ball 31b will turn in slide 35b and will move longitudinally thereof.

Thus, it will be apparent that the two tubes 32 have their rear ends universally connected to the stage 20 and their forward ends universally connected to the support II. The forward ends of the two tubes will always lie close to each other. However, the distance between the rear ends of the two tubes may be varied by adjusting the knob 29. Furthermore, the vertical position of the rear end of each of the tubes may be varied by adjusting the position of the member 24 on the member 23. The stage may move in a rotary path and thereby carry the rear ends of the members 32 in a rotary path. Obviously, this will cause the primary targets 24e carried by the members 32 to move simultaneously in the same direction and to the same extent through closed paths and the targets will be prevented from rocking relative to the line of sight and from overturning. The universal connections will permit such movement of the members 32. During this movement the patient may be viewing the targets through the lenses I9. In order to prevent all of the weight of each member 32 being applied to the stage 20, a counterbalance spring 34a is associated with the pivot point 34. This spring is so arranged that it will tend to swing the rear end of member 32 upwardly so as to relieve the stage 20 of part of the weight thereof.

Light shields I68 may be associated with the forward ends of tubes 32 to prevent light from outside sources from entering tubes 32 in any appreciable amounts. A brow rest I6I may also be associated with the forward end of tubes 32. In using this device a single primary target 24a is mounted in the rear end of each of the tubes 32. As previously stated, this is done by placing one of the targets 24c in one of the slots I55. The patient is seated before the instrument and will View the targets through the lenses I9. When the lights 38 are on, the primary targets will be illuminated and the patient looking through the tubes 32 will see these targets. The patient can fuse these targets when the rear ends of the members 32 are adjusted to the proper :1

vertical position by moving the members 24 vertically on the members 23 and when the rear ends of the members 32 have been adjusted the proper distance apart by means of the knob 29.

Then if the motor of the machine is started, the

stage will move in a rotary path and the primary targets will consequently be carried in a rotary path. In the main, the treatment of the patient with this instrument may be carried out in substantially the same way as described in my prior patent by merely using the primary targets alone.

With this instrument, however, I have provided a different arrangement for stimulatin or inhibiting accommodations by changing fixation from the primary targets 24a to secondary tarfilters I 58a and the images thereof will be reflected by the lens I9a forwardly through the lenses I9 into the eyes of the patient. The lights 38 when on will be reflected through the targets 24c, causing the images thereof to be reflected through lenses I9a, lenses I9 into the eyes of the patient. The interior of tube 32 and of the lower portion of member I5I preferably is provided with a dull finish I62.

In the overcoming of any anomalies of convergence or accommodation it is very desirable to keep the eyes of the patient light-adapted at all times. However, it is desirable also to stimulate or inhibitaccommodation and convergence by changing fixation from one set of targets to another.

To do this, I control the lights I54 and 38 in such a manner that during a short period the lights 38 will be on, illuminating the primary targets 246 so that they can be seen by the patient, and the lights I54 will be off so that secondary targets 24a will not be seen. During the next period, the lights I54 will be on so that secondary targets 24a can be seen by the patient and the lights 38 will be off so that the primary targets cannot be seen by the patient. Thus, even when fixation of the eyes on the targets is changed from the primary to the secondary targets and vice versa, the eyes are kept lightadapted.

With this arrangement both monocular and binocular accomodative exercises may be carried out. Monocular exercises may be carried out by having one of the primary targets illuminated while the other is not and one of the secondary targets illuminated while the other is not, the illumination periods of theprimary and secondary targets alternating. Binocular exercises may be carried out by having both primary targets illuminated while both secondary targets are dark, and vice versa, the'periods alternating at intervals. The instrument is preferably constructed so that the secondary target position is 2.50 diopters closer to the lens I9 than the primary target position which is at infinity provided the primary target is at the zero position on scale I55a. Thus a change in fixation from the primary target to the secondary target demands 2.50 diopters of accommodation and no change in convergence. By inserting auxiliary lenses in the sockets I91) and adjusting the rear ends of tubes 32 to change the convergence angle, almost any adductive and accommodative demand can be instituted, either in ratio or in any amount, either function in advance of the other. The principle of this training is the rapid change in binocular focus requirement from stimulation to inhibition, with the convergence angle fixed,

by alternating fixation from infinity to a near point.

The transparent member I9a is preferably in the form of a base-down prism to eliminate the phantom image from secondary target 24a which would otherwise be caused by the double reflection from opposite surfaces of member Illa into the eye of the patient causing him to see two images.

In theseexercises, it is desirable to use color filters in order to obtain a monochromatic light. It is preferable that the color filters I53a in as-. sociation with the secondary targets be of a stimulating color to obtain a stimulating effect. It is preferable that the color filters I58 in association with the primary targets be of .an inhibitory color to obtain a sedative effect.

I provide 'means for controlling and flashing the lights I54 and 38. This means isof such a nature that it may be set to turn on lights 38 and simultaneously turn oiT lights I 54 and vice v-ersa at intervals. The periods the lights 38 and I54 are on and olT may be adjusted relative to each other as desired. Furthermore, the light I54 and the light 33 for either tube may be flashed independently of the lights for theother tube. Also, one of the lights 38 may be on with the corresponding light I54 simultaneously off while the other light 38 is off with the corresponding light I54 simultaneously on, and vice versa. The intensity of the lights for either eye may be controlled independently of the intensity of those for the other eye. The illumination for one eye may be completely interrupted without affecting the illumination of the other eye. The light for one of the targets 246 may be flashed while the light for the other target 24c may be constant. Various other illuminating combinations may be obtained with my instrument for various purposes.

Inv Figure 6, I illustrate a circuit which may be used for controlling the operation of the lights 33 and the lights. I54 and other parts of my instrument. Portions of this circuit are the same as the circuit disclosed in my prior patent and need not be described in detail.

The circuit comprises wires I25 and I25a leading from a sourceof current. Wire I25 is connected to a-motor 42 of a type disclosed in my prior patent. This motor 42 drives the mechanism disposed within housing 4 as described in my patent. A switch MI is interposed in the line I25 for making and breaking the circuit to motor 42. The line I25a leads to. a master switch I33a. The switch I38a is also connected to a line I35. A line I39 leads from line I35 and is connected to a jumper plate I40 which is also connected to a line I42. When alternating current is employed, the jumper plate I40 is used but when direct current is employed this plate is removed. The line I42 is also connected to the motor reversing switch 80. A resistance element I3! is interposed in line I39. A line I36 leads from plate I40 to line I35 to which it is connected.

The line I35 leads'to one of the double pole double throw switches Ma and is connected to a pole 129a thereof. Two of these switches 4Ia are provided and are identical with each other. One switch is for controlling the lights of one of the tubes 32 and the other switch is for controlling the lights for the other tube 32. The pole I23a of the left-hand switch is connected by a line I32 to the pole I29a of the other switch. Each of the switches is provided with a dead pole I30a. Furthermore, each of the'switches is provided with poles I29 and I30. Movable contact members I3I and I3Ia are also provided on each switch. The members I3I and I3Ia are adapted to be moved simultaneously by suitable means. The members I3I and I3Ia are adapted to be .in contact with poles I33a and I29a, respectively, or with poles I30 and I29, respectively. The poles I30 of the switches 4Ia. are connected by a line I2'Ia to the lights I54 in series and the line I2Ia. is

also connected to line I251) at a point between lights I54. This line I25b is also connected to line I21 at a point between lights 38. This line I2! connects lights 38 in series and is connected to rheostat switches 40a which are employed for controlling the intensity of illumination of the lights for each tube 32. The left-hand rheostat switch 40a is connected to the contact member I3Ia of the left-hand switch 4Ia by a line I33a. The right-hand rheostat switch 40a is connected to the contact member 'I3Ia of the right-hand switch 4Ia by a line I331). The line I331) is connected to a pole I 330 of a three pole double throw switch indicated by numeral 4Ib which includes the movable contact member I33d. The line I33a is connected to the pole I33e of switch M?) which also includes the movable contact member I33f. The contact member I33d is connected by line I33g to the movable contact I3I of the left-hand switch Ma. The pole I3I of the right-hand switch 4Ia is connected by line I33h with the movable contact I331. The pole I29 of the right-hand switch M11 is connected by line I 331 to the movable con tactmember I33Ic of switch Mb. The pole I29 of the left-hand switch 4| is connected by line I331 to a line I34. Additional poles I33m, I33n, and I330, are associated with the movable controls I33d, I33k, and 133 respectively of switch 4Ia. Means is associated with switch Mb for moving all of the movable contact arms I33d, I337c and I33 simultaneously. The line I34 has its upper end connected to pole I33m. Poles I33n and I330 are connected to each other by line-I33p which is also connected to line I34a. The line I34a has its upper end connected to pole I33q which is also associated with movable contact member I33Ic. The line I34 has its lower end connected to a contact 500 of a flasher switch 50b. The line I34a has its lower end connected to the other contact 500 of flasher switch 5021. A pivoted lever 49b carries a contact 59d on its lower end which is adapted to alternately engage the contacts 500. This lever is moved about its pivot point at proper intervals by means of a cam 49a. This cam may be carried on a shaft 41b which is driven by motor 42 in a suitable manner. The cam 49a is preferably made of two flat members of different contour which may be adjusted relative to each other to vary the intervals at which lever 49?) is swung about its pivots. This cam is preferably of such a nature that a slow flashing of the lights will be obtained and, as previously stated, the speed of flashing can be varied. The line I34a also is connected by line I342) to a contact arm 50a of a flasher switch 50. The line I34 is connected by a line I340 to a contact arm 50a of the other flasher switch 50. The other arms 50a of the flasher switches are connected together and to the line I35 by a line I35a. A single pole double throw switch I3b is provided for selectively connecting line I35 to line [35a or line I35 to line I351). The line I 35b is connected to contact arm 50d carried by lever 49b. The contacts 50a of switches 50 are normally spaced apart but are alternately engaged by a cam 49 mounted on a shaft 41 (corresponding'to shaft 4'! of my prior patent) which is driven by the motor 42.

With this circuit and cooperating parts the following results can be obtained:

Master switch I38a may be opened or closed to deenergize or energize the entire circuit.

Motor switch I4I may be opened or closed to deenergize or energize the motor circuit independently of the rest of the circuit. 7

Motor reversing switch will be operated by means described in my prior patent to reverse the motor at intervals.

Rheostat switch 400 at the left may be operated independently to control the intensity of illumination for the left eye.

Rheostat switch 40a at the right may be operated independently to control the intensity of illumination for the right eye.

Switch 4Ia at the left may be operated independently so that contact members I3I and I3Ia will contact with poles I30a and I29a, respectively. for obtaining constant illumination of light 38 for the left eye or so that they will contact with poles I30 and I29, respectively, for obtaining alternate flashing of light 38 and light I54 for the left eye.

Switch 4Ia at the right may be operated independently so that contact members I3I and I3Ia will contact with poles I30a and I29a, respectively, for obtaining constant illumination of light 33 for the right eye or so that they will contact with the poles I30 and I29, respectively, for obtaining alternate flashing of light 38 and light I54 for the right eye.

Switch I3b may be operated to selectively connect, flasher switches 50 into the circuit for lights 38 and I54 to obtain fast alternate flashes of lights 38 and I54 or to selectively connect flasher switch 50b into the circuit for lights 38 and I54 to obtain slow alternate flashing of these lights. When switch 50b controls the flashing, the on or off periods may be varied by adjustment of cam 49a. When switches 50 or 50?) control the flashing, the speed of flashing may be varied by varying the speed of motor 42 by the speed control described in my prior patent.

Switch IIa may be operated to move contact arms I33d, I33lc and I33 to the right into contact with poles I330, I33q and I332, respectively, to produce an alternate flashing, that is with the lights 38 and I54 for one eye flashing alternately with the lights 38 and I54 for the other eye or to move contact arms I33d, I33lc and I33 to the left into contact with poles I33m, I33n and I330, respectively, to cause lights 38 for both eyes to flash on and oif simultaneously and lights I54 for both eyes to flash on and off simultane ously. However, in both positions of switch 4Ia, when the light 38 for one eye is on the light I54 for that eye is off and, vice versa.

Thus, it will be apparent that with this instrument I provide means for changing fixation from primary to secondary targets, While keeping the eyes constantly light-adapted. I have found that this arrangement is very desirable for stimulating or inhibiting accommodation.

Although I have specified that secondary targets are provided in the target-carrying members II, the instrument can be used without such secondary targets. When used in this manher the bulbs I54 will serve as a source of light for keeping the eyes light-adapted when illumination of the primary targets has been interrupted.

Although I have stressed that the members I50 are provided for receiving the secondary target-carrying members I5I and light housings I53, they serve an additional purpose when the secondary targets are not being used. As illustrated in Figure 4, the image of the eyeball will be reflected in the angularly disposed lens I9a when the patient is looking into the tube 32. This image can be seen by the practitioner when he looks downwardly through the member I50. Thus, these members I50 serve as a means for checking fixation.

With the arrangement illustrated in Figure 4, however, when the practitioner looks down through the member I50 two images of the eye will appear in the member I So. The phantom image caused by different reflections of the light, coming from the eye of the patient, by opposite surfaces of member I9a can be eliminated by the arrangement illustrated in Figure 7. Also, with this arrangement it will not be necessary to remove light housing I53 and secondary target carrying member I5I to observe fixation of the eye. An additional peep-hole I502) may be provided behind member I50. An additional diagonally disposed transparent member I9d will be disposed in tube 32 below this peep-hole. This member will be in the form of a base-up prism. The combination of the proper basedown prism I and base-up prism I9b will eliminate the phantom image of the eye of the patient which would otherwise appear to the practitioner.

It will be apparent from the above description that I have provided apparatus for orthoptic training purposes having many advantages many of which have been discussed herein and others of which will be apparent from the drawings and the following claims.

Having thus described my invention, what I claim is.

1. An optical instrument of the type described comprising a pair of elongated hollow members so mounted that a patient may look through the forward ends of such members, a translucent target mounted adjacent the rear end of each of said members, a source of light in each of said members behind each target, a separate source of light associated with each of said members so arranged as to direct light into the member adjacent its forward end, and means for flashing both of said sources of light in such a manner that when one is off the other is on, said hollow members being substantially horizontally disposed and having their forward ends mounted in substantially fixed relationship and their rear ends mounted for adjustment relative to each other, the rear ends of said members being carried by a member movable in a closed path in a substantially vertical plane.

2. An optical instrument of the type described comprising a pair of elongated hollow members so mounted that a patient may look through the forward ends of such members, a translucent target mounted adjacent the rear end of each of said members, a source of light in each of said members behind each target, a separate source of light associated with each of said members so arranged as to direct light into the member adjacent its forward end, a second translucent target associated with the latter source of light, and means for flashing both of said sources of light in such a manner that when one is off the other is on, said hollow members being substantially horizontally disposed and having their forward ends mounted in substantially fixed relationship and their rear ends mounted for adjustment relative to each other, the rear ends of said members being carried by a member movable in a closed path in a substantially vertical plane.

3. An optical instrument of the type described comprising an elongated hollow member so mounted that a patient may look through the forward end of such member, a translucent target mounted adjacent the rear end of said member, a source of light behind said target, said member being provided with a transversely extending extension, a translucent target disposed mounted that a patient may look through the forward end of such member, a translucent target mounted adjacent the rear end of said member, a source of light behind said target, said member being provided with a transversely exending extension, a source of light in said ex- 3 tension, a transparent member located in said member in line with said extension for reflecting the light'of the source in said extension from the forward end of said member, and means for flashing both of said sources of light in such a manner that when one is off the other is on.

5. An optical instrument of the type described comprising an elongated hollow member so mounted that a patient may look through the forward end of such member, a translucent target mounted adjacent the rear end of said memher, a source of light behind said target, said member being provided with a transverselyextending extension, a translucent target disposed in said extension, a source of light behind said target, a transparent member located in said member in line with said extension for reflecting the image of the second target'from the forward end of said member, and means for flashing both of said sources of light in such a manner that when one is off the other is on, said transparent member being prismatic toeliminate phantom image of the second target.

6. An optical instrument of the type described comprising a pair of elongated hollow members so mounted that a patient may look through the outer ends of such members, a translucent target mounted adjacent the inner end of each ofsaid members, a source of light in each of said members behind each target, a separate source of light associated with each of said members so arranged as to direct light into the member -adjacent its outer end, and means for flashing both of said sources of light in such a manner that when one is off the other is on, said hollow members having their outer ends mounted in substantially fixed relationship and their inner ends mounted for adjustment relative to each other, the inner-ends of said members being carried by a member movable in a closed path in a plane substantially normal to the axes of said members. "7. An optical instrument of the type described comprising a pair of elongated hollow members so mounted that a patient may look through the outer ends of such members, a translucent target mounted adjacent the inner end of each of said members, a source of light in each of said members behind each target, a separate source of light associated with each of said members so arranged as to direct light into the member adjacent its outer end, a second translucent target associated with the latter source of light, and means for flashing both of said sources of light in. such a manner that when one is off the other is on, said hollow members having their outer ends'in substantially. fixed relationship and their inner ends mounted for adjustment relative to each other, theinner endsof said members being carried by a member movable "in a closed pathin a plane substantially normal to the-axes of said members.

8. An optical instrument of the type-described comprising a pair of elongated hollow members so mounted that a patient may look through the forward ends of such members, a translucent target mounted adjacent the rear end of each of said members, -a source of light in each of said members behind each target, a separate source of light associated with each of said members so arranged as to direct light into the-member adjacent its forward'end, and'means for flashing both of said sources oflight in such a manner that when one is off the other is on, said hollow members being substantially horizontally disposed, the rear ends of said members being carried by a member movable in aclosed path in a substantially vertical plane.

9; An optical instrument-ofthetype described comprising a pair of elongated hollow members so mounted that a-patient may-look through the outer ends of such members, a'translucent target mounted adjacent the rear end of each of said members, -a sourceof'lightin eachof said members'behind each target,a separate source of light associated'with eachof said-members so arranged as to direct light intothe member adjacent its forward end, a-second translucent target associated with the lattersource of light, and means for flashing both of said sources of light in such a mannerthat when oneis oil the otheris on, said hollow members being substantially horizontally disposed, the rear ends of said members being carried by a member movable in a closed path in a substantially vertical plane.

10. An optical instrument of the typedescribed comprising a pair of elongated hollow members so mounted that a patient may look through the outerends of such members, a translucent target mounted adjacent the inner end of each of said members, a source of light in each of said members behind each target, a separate source of light associated with each of. said members so arranged as to direct light into the member adjacent its outer end, and means for flashing both of said sources of light in such a manner that when one is off the other is on, said hollow members having their outer ends pivotally mounted and having their inner ends carried by a member movable in a closed path in a plane substantially normal to the axes of said members.

11. An optical instrument of the type described comprising a pair of elongated hollow members so'mounted that a patient may look through the outer ends of such members, a translucent target mounted adjacent the inner end of each of said members, a source of light in each of said members behind each target, a separate source of light associated with each of said members so arranged as to direct light'into the member adjacent its outer end, a second translucent target associated with the latter source of light, and means for flashing both of said sources of light in such a manner that when one' isofi" the other is on, said hollow members having their outer ends pivotally'mounted and having their inner ends carried by a member movable in a closed path in a plane substantially normal to the axes of said members.

LE ROY WOTTRING.

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