US2255689A - Means of recording eye movements - Google Patents

Description

P 9, 1941- c. c. TAYLOR ET AL 2,255,689

MEANS OF RECORDING EYE MOVEMENTS Original Filed Feb. 15, 1957 5 Sheets-Sheet 1 INVENTOR. (2724 6'- 7 774016 JAMES X 77776018 5 Sheets-Sheet 2 m 6 mm 72 mmm. m w ,2 w X we NW ..x. 2 \w a: S T Q Q 2 \X m L 59 QFW F 3 .CJ m

Sept. 9, 1941.

Original Filed Feb. 13, 1937 Sept. 9, 1941. c. c. TAYLOR ET AL MEANS OF RECORDING EYE MOVEMENTS Original Filed Feb. 13, 1937 5 Sheets-Sheei 3 \IlQlllllIlllll INVENTOR. 63 7 61, 63 777x402 JHMES X 777x002 Sept. 9, 1941. c. c. TAYLOR ET AL MEANS OF RECORDING EYE MOVEMENTS 5 Sheets-Sheet 4 Original Filed Feb. 13, 1937 Y Q im kw R Y Ar H 6% W \M,% Q- an, as E\ .0 p CM W Q N m W4 Z l 3/ Mm 5 WW V Y B N m- :N am h A l 7! a! Sept. 9, 1941, c -c. TAYLOR ET AL 2,255,689

MEANS OF RECORDING EYE MOVEMENTS Original Filed Feb. 13, 1937 5 Sheets-Sheet 5 [A Q Q g I Q a i I i I i l g INVENTOR. Q a C921, 6. 779x405 {Q2 M m Q B k HMES Tan/am "I'll In 'I I'll" Y WW1 9% Fatented Sept. 9, 1941 2,255,689 MEANS OF aEooRmfio EYE MOVEMENTS Carl C. Taylor and James Y. Taylor, Brdwnwopd, Tex., assignors to Educational Laboratories, Inc., Brownwood, Tex.,a corporation of Texas Original application February 13, 1937, Serial No. 125,674. Divided and this application October 7, 1938, Serial No. 233,782

1 Claim. (c1. 8820) This invention relates to new and useful improvements in eye photographing devices, and has particular reference to novel means of recording eye movements.

This application is a division of our application Serial Number 125,674, filed February 13, 1937, for Means and method of recording eye movements.

One object of the invention is to provide an improved device for photographing movements of the human eye.

Another object of the invention is to provide a compact device for photographing the binocular eye movements of a person while reading and which will record the binocular movements of the eyes simultaneously either with or without the patient wearing correction lenses before the eyes. I

Another object is to provide means in an eye movement photographing device whereby only the light reflected by the corneas of the eyes may be sharply focused on the photographic recording film of the device and which will greatly magnify the minute movements of the eyes with the film at a relatively short distance from the eyes.

Another object of the invention is to arrange the fixation means or readingmatter, sources of illumination, and eye movement focusing means at such an angular relation to each other that substantially only light reflected from the corneas of the eyes will be reflected into the focusing means.

Another object is to control the speed of travel of the moving film so as to provide means whereby the speed of reading and the binocular movements of the eyes at said speed may be quickly, easily, and accurately determined.

Another object is to provide an apparatus for making photographic records of the binocular eye movements of a person while reading or observing accommodation stimulating indicia, which has means for positioning the persons head relative to the objective of the photographing apparatus so that in the case of a person wearing corrective lenses, the reflections from the lenses will not interfere with the taking of the photographic record.

Another object is to provide a novel means of determining the muscular imbalance or im-,

balance of innervation of the muscles which control the accommodation and vergence functions of the eyes.

Another object is to provide an improved apparatus for readily determining the cooperation or lack of cooperation of the binocular vision functions of the two eyes during the persons normal reading by photographically recording the simultaneous movements of the persons eyes on a photographic film which is moved at. a

constant speed, thereby giving a graphic record of the relative movement of the persons eyes at succeeding time intervals while the person is "reading.

Another object of the invention is to provide an improved device for photographing eye movements, which can be operated in a lighted room,

thereby eliminating the necessity of photographing in a dark room.

Still another object of the invention is to provide an improved device for photographing eye movements of a person while reading, having ascertained by observing the film.

A further object of the invention is to provide an improved device for photographing the eye movements of a person reading, which is cheap and simple in manufacture and which takes up very little space when in use, and which is also readily portable. 7

An important object of the invention is to provide an improved device having means for focusing eye movements on a film, whereby said movements are recorded thereon, and also having a simple adjustment for the focusing means.

Still another object of the invention is to provide an improved device for photographing the eye movements of a person while reading and including means for holding the persons head rigid during photographing, said means being adjustable for each person.

Another object of the invention is to provide an improved device for photographing eye movements which includes lenses for focusing the eye images on a traveling film, said lenses being mounted so as to be universally adjusted manually by the operator.

A still further object of the invention is to provide lenses for focusing eye images on a traveling film and a view finder including a mirror on to which'the images are focused, the images on An important object of the invention is to pro- 7 vide an improved eye photographic machine having text or indicia to be read by the subject during the photographing, and having means for concealing this test from, thersubject while pre-,

I liminary adjustments and observations are made prior to the actual photographing.

A construction designed to carry out the invenfrom a reading of the following specification and I by reference to the accompanying drawings in which an example of the invention is shown, and I wherein:

2,255,6Q F essential that the eyes be photographed through the corrective lenses. With this problem in mind and with the problem of forming simple, eiiicient, and economical means for photographing the binocular movements of the eyes simultaneously,

7 and which although compact in structure would enable the magnifying or amplifying of the mi- 'nute movements'of the eyes so as to obtain records 'whichmightbe easily and accurately studied, we

Figure 1' is a side elevationiof'an eye photo Figure 2 is a longitudinal sectionalview of the same;

Figure 3 is a plan view of the same; Figure 4 an end elevation of thesame; Figure 515 a partial elevation of the side opposite that shown in Figure 1;

Figure 6 is a partial longitudinal sectional view of the view finder;

Figure 7 is a vertical sectional View of the same taken on the line 1-1 of Figure 6; V

Figure 8 is a detail sectional View of the lens mounting; 7

' Figure '9 is a partial 'front' elevation of the same;

Figure 10 Figure 11 is a sectional detail of the same;

Figure 12 is a detail of the filmfwinding reel drive connection: and

Figure 13. is a diagrammatic View illustrating the function of the device embodying the inven- 1 tion as regards its use in photographing the i movements of the eyes through correction lenses.

Photographic devices for recordingthe movements of the eyes have, in most instances in the past, been designed for laboratory use and as far as we are aware, lenses having a long focus were used to focus the eye movements on to the recording film. The object of using a long focus lens was to magnify the minute movements of the eyes so that they could be readily distinguished on'the film. Because of said long focus lenses it was essential to use a'relatively long housing. This, therefore, made the prior art instruments very cumbersome and impractical for commercial use. Most prior art instruments photographed only the movements of one eye and for this reason did not'provide a binocular record I of the eye movements whereby the binocular coordinationrof the two eyes could be studied;

Due to the fact that mostof these prior art instruments only recorded the monocular movements of an eye, errors 'of accommodation as ;well as errors of vergence could notLbegstudied, as no means were provided on the record whereby the movement of one eye could be compared with themovement of the other eye as used binocularly, for examplewhen reading. 7 1

It was also found that with most prior artv instruments, photographic records of the eye move- Jments, could not be obtained when corrective lenses were in position before the eyes, as it was irnpossiblein mo'stall instances to obtain a satiisfactory photographic record of the eyemovefments throughsaid corrective lenses;

In view of the fact; therefore, that We are paris a detail of the film drive sprocket clutch;

1 graphing device constructed in'accordan ce with Q I the invention;

carefully considered the problems involved and carefully designed and computed the various ing a transverse supporting member I2 rigidly secured to its I rear end-by triangularlshaped brace members I3 Figure 3). Although the member I2 is shown as a separate piece and secured to the bar II, it can be made integraltherewith. .The forwardend'of the bar II is formed with a flat yoke II. I r

The member I2 has depending lugs I4 at its ends and a transverse angle bar I5 is fastened by bolts I6 to the lugs. Suitable rubber feet or Washers I5 are inserted between the lugs and the bar, the bolts I fi passing'through the angle bar and washers, and being fastened into the lugs, as shown in Figure 1. Lugs II, similar to the lugs I4, depend from the shoulders of the yoke II and have a transverse angle bar I8 secured thereto by bolts I9. Rubber washers I8 are positioned between the lugs and angle bar. A longitudinal tubular rod '26 has its ends secured to the central portions of the angle bars and has a tubular vertical depending leg 2| made integral therewith. It is pointed out that the rod 20 is positioned at an angle in a horizontal plane, the leg 2I' being substantially vertical. 7

The lower end of the leg is slidable in a tube 22 extending upwardly froma stand 23. A set screw 24 having a'suit'able hand knob 24 is threaded through the tube 22 and its inner end engages the leg H to hold said leg in a desired position within the tube. It is obvious from the foregoing that the frame III is carried by the longitudinal rod 20 and may be raised or lowered position of the leg within the tube 22.

A housing 25 (Figures 1 and 2) is mounted on the bar II at the rear-end thereof and is secured at its rear by a verticalbrace 26 and at its forward end by a suitable bracket 2 7. The housing is divided into ;two compartments 28 and 29, in which the entire camera mechanism is mounted. The film supply reel 30 is demountably secured on a shaft 3| in the forward compartment 29. The film 32, unwinding from the reel, passes upwardlythrough a guide channel 33 on the rear wall of the compartment 29;and then through an opening'34 in said wall and-into the rear compartment 28. In the upper end of this latter compartment; and adjacent the opening 34, a film an opening 36 in a film winding box 36. The box 36 is removably mounted in the compartment 28 and has a film winding reel 31 journaled on abearing 38. carried on a shaft 39 supported in one side of the housing 25. The inner end of the sha'f-t 39 has a slot 39 (Figure 12) which is arranged to engage a pin 40 which extends transverselywithin the reel 31. It is obvious that rotation of the shaft will drive the film reel 31, when said reel is in position within the compartment 28. The compartments are normally closed by sliding side doors 28 and 29.

The housing is provided with an elongated flared --ex-tensio'n 40 which extends forwardly therefrom, being supported by and secured to the top of-the bracket 21. The rear end of the extension is open, whereby the interior of the case communicates with the interiorof the forward compartment 29 of the housing. A transverse horizontal partition 4| is positioned in the compartment 29 and this partition is substantially flush with the bottom of the extension, thus forming a continuous passage from the forward end of said extension to the rear wall of the compartment 29.

The lenses of the camera (Figures 8 and 9) are mounted to be universally adjustable in the forward wall of the extension 48. Each lens is supported in a tube 43 which is slidably mounted in a, sleeve 44, which extends through a circular opening 45 in the front wall of the extension. The sleeve is eccentrically mounted in a disk 45, which is larger in diameter than the opening 35, whereby forward displacement of the disk and sleeve is prevented. The disk 45 is eccentrically confined within a ring 4'! which is secured to the rear of the front wall of the extension by a spring washer 4'! suitably secured to the inner periphery of the ring. It is obvious that due to the eccentric mounting of both the sleeve 44 and the disk 46, each lens 42 carried by the sleeve is universally adjustable in all directions. By mounting the lenses as shown, a maximum adjustment of said lenses is had in a minimum amount of space.

A head clamp 55) (Figures 1 to i) is provided at the forward end of the machine, This clamp is arranged to hold the head of the person in position during the photographing of his eye movements. The clamp includes a pair of standards which extend upwardly from the arms of the yoke II. The standards are connected and braced at their upper ends by a transversetie rod 52 which is fastened to said standards. A similar rod 53 braces the lower end of the standards. The bar 52 has a transverse angle bar 52' secured thereto and this bar carries a pair of loosely pivoted forehead rests or stops 54,. suit ably secured in bearings 55 made integral with the bar, whereby said stops are adjustable with relation to said bar.

A support 56 is secured on the lower transverse rod 53 at the central portion thereof "and a bracket 5'! is adjustably secured to the support by a set screw 58. The screw is provided with a knurled knob so as to be readily turned by hand. The bracket extends forwardly from the support and has a bearing 51' at its outer end. Ascrew 58 having a knurled knob at its lower end is threaded through the bearing and carries a chin rest 59 at its upperend. -It is obvious that the chin rest can readily be raised or lowered with relation to the bracket by merely rotating the screw. V

. As.;show.n in. Figure ..1,. the person whose eye movements are to be photographed places his chin on the chin rest 59 and his forehead against the stops 54 on the transverse bar 52'. For clamping the sides of his head and to prevent transverse movement of the same, a pair of arms 60 extend forwardly from the upper end of each standard. The rod 52 passes through the rear end of each arm, whereby said arms are pivotally mounted thereon; Suitable bearing members 6%! arepositioned on the rod 52 between the arms and the-standards 5|. The rod has a head 6| on one end-thereof and has a nut 6| on its opposite end. -'By tightening the nut 6! the arms 60 are frictionally clamped in position with relation to the standards.

A screw 62 having a knurled knob is threaded through the outer or forward end of each arm and each screw carries a clamping disk 63 at its inner end. The arms are connected and braced by a bar 64. Thus, it will be seen that when a persons-head is placed in the clamp 58 and the proper adjustments of the clamping disks 63 and the chin rest 59 are made, the head is held in a rigid, immovable position. The adjustments are easily and quickly made so that the clamp will readily fit any size head.

For supplying sufiicient and proper light for photographing the eye, a pair of suitable electric lamps 65 are provided. Each lamp is positioned within a cylindrical casing 68. The casings are mounted, one at the rear end of each arm ll of the yoke ll. Each casing is provided with a small opening 61 in its'forward side, and these openings are so positioned that light rays escaping therefrom will reflect directly into the eyes of the person whose head is held in the clamp 50 (Figure 1). It is this light cast into the eyes and reflectedby the cornea of the eyeswhich is picked up by the lenses 42 and focused on the film. A small square opening 68 is provided in the rear wall of each lamp casing 66 to permit the escape of light. This escaping light serves to illuminate the reading cards, which are supported in a holder Ill.

The holder is secured to the forward end of the bracket 2! and includes a rigid card holder H which carries a card 12 with indicia thereon. A flap 13 of the same size as the holder H is pivoted to the holder at its upper end and when the flap is in its lowered position, it covers the card 12, hiding it from the view of the subject. If desired, a second card 13 can be supported on the front side of the flap. It is the indicia on these cards that is read by the person while his eye movements are being photographed.

For obtaining the correct adjustment of the lenses so that the light rays reflected from the eyes will be focused directly on to the center of the film, a View finder (Figures 2, 6 and '7) is provided in the housing 25 above the compartment 29. The finder includes a mirror 15 which is secured at its upper end to a rock shaft 16 which is journaled in the housing 25,.adjacent the opening 34 in the rear wall of the compartment 29. One end of the shaft extends outwardly through the wall of the compartment and is provided with a short vertical rocker arm ll. By swinging the arm the mirror is swung to either he across the passage between the lenses and the film or to be in a raised position against the underside of the top of the housing 25 to unobstruct the passage.

With the mirror in a lowered position, as shown in Figure 2, the light rays comingthrough the lenses are caught thereby and are -visible on a section of ground glass 18' which covers an opening 78 inthe top of the housing. The opening is f arranged to be closed by a sliding panel 19 pro- 1 vided with a suitable hand knob 80. Attachedto 1 spring drive 90. 35 is rotating to drive the film through the housing, the winding reel is also rotated to hold the 3 filmtaut at all times. a The person whose eye movements are to be photographed places his head in the head clamp 59. 1 justed to position his head so that the light rays f from the lamps 65 emitting through the openings 61 in the cylindrical casings 66 willshine direct- I ly in his eyes. By disposing the frame and machine at an angle, it is possible for aperson who tions.

the knob is a short arm 8| which extends rear- 11 rotates the shaft/T6 to swing the mirror upwardly against the underside of the top of the 1 housing 25, whereby the passage between the lenses is unobstructed and the light rays are focused directly on the film.

For driving the film through the device, an electric motor 83 is mounted on one side of the 3 housing 25 and is controlled by a suitable switch H83. The drive shaft '84 of the motor has con- 1 nection through a clutch 8'5 with the shaft 35' of the drive sprocket 35. The particular construction of the clutch is clearly shown in Figures 10 and 11. The clutch includes a pulley 86 mounted i on the end of the drive shaft 84 and thispulley has a split spring washer 81 fastened to its outer face. The sprocket shaft 35' has an enlarged j knurled hand disk 88 on itsouter end-and the outer face of the disk is adjacent the spring wash- 1 er 87. A pin 89 onthe outerface of said disk is arranged to be engagedb-y the end of the split spring washer when. the pulley 86 is rotated.

. By observing Figure 11, it will be seen that the disk 88 can be rotated in acounterclockwise direction by hand and thepin 89 will ride against the outer face of the spring washer depressing the same and makingno connection therewith.

: Thus, the sprocket 35 which is rotated when the 1 disk is turned can be rotated manually without affecting any of the other parts.

However, the clockwise rotation of the disk and sprocket is prevented by the pin 89 striking the projecting end of said spring washer. operating, the pulley 86 and spring washer 81 When the motor is are rotated in a counterclockwise direction and the projecting end of the washer will engage the 3 pin and rotate the disk 88 and sprocket shaft 35 therewith, whereby the sprocket 35 is driven to cause the film to unwind from the supply reel 1 39 to the take-up reel 31.

To take care of slack in the film and keep the I film taut during operation, a pulley 16' is mounted on a driveshaft 39 (Figure 5), which drives the film winding lreel. This pulley is connected with the pulley Men the motor shaft by a crossed Thus, while the drive sprocket The clamping disks and chin rest are adis wearing eye glasses with bifocal lenses, to bserve the cards on the card holder through said :bifocal lenses, whereby his eye movements will be photographed under normal reading condi- It is noted that at first the motor is not operating, The panel 19 (FiguresG and'?) is then ;s1id ;upwardly-to uncover the openingj'l8 in the ,topof the" housing25. L Thismovement' lustrates how it is possible with the device empermits the mirror 15 to swing downwardly un der its own weight, across the passage between the lenses i2. and the film 32. The person is now observing the card 13' on the flap 13. The light rays from the lamps 65, which are shining in the eyes, are reflected from the cornea of the eyes into the lenses.

As can be seen from the drawings the head rest is designed to position a persons head so that his eyes are in front of each of the camera objectives and so that the longitudinal axis of the latter will be inclined downward relative to the plane of straight ahead vision of the eyes from thefront to the back of the camera. The rays of' light which project from the small holes 61 in the covers 66 strike the eyes and corrective lenses at such an angle that the reflections produced by the surfaces of the corrective lenses will not be focused on the film when the camera lenses 42 are adjusted to focus the light reflected from the eyes on said film. I

It will be noted that the angle the rays of light from the holes 61 make with the camera axis is approximately the same as the anglethe axis of the camera objectives make with the plane of straight ahead vision. Although this angle is not extremely critical, it is important that the position of the light source be such that the rays from the virtual images of the corrective lenses are not brought to a focus on the .film when acute angle or are inclined approximately twen-,

ty-five degrees withv respect to the plane of straight ahead vision of the patients eyes, the reflections from the corrective lenses will not prevent taking a photographic record of the refiections from the eyes, that is, providing the rays of light from the source of illumination strike the cornea from an 1 angle considerably above or below the axis of the camera objective. This is partly due to the fact that the plane of the corrective lenses is usually inclined slightly forward at the top. The source of illumination may be above or below the axis of the photographic objective, but when the rays project from within the plane of the axes of the objective lenses the reflections from one eye glass interferes either with the record of the corresponding eye or with the record of. the other eye, depending upon the angle the raysmake with the axes of the camera objectives.

This will probably be better understood by referring to Figure 13 which diagrammatically ilbodying our invention to photograph the eye movements through corrective lenses. In this figure the tube 43 supporting the focusing, lens 42 of the camera is diagrammatically illustrated. Thefilm 32 is shown as being moved in the rear of the guide channel 33 in therear wall of'the compartment 29.' This guide channel is provided with a stop opening 98 thereby'expos'ing a portion only of the film depending, of course, upon the area of said stop opening.

The tubular member 43 is formed relatively long so that the end 99 thereof functions as. a stop opening along the .path ofthelight focused, from the cornea of the observers eye illustrated at It"). The angle'of theline of sight while viewing-the opening 51 of the lamp housing 66 relative to the axis-of the focusing means andllne of'sight IOI is also diagrammatically illustrated. The prescription lens I02 is diagrammatically illustrated in its related position before the eye of the observer.

Now referring more particularly to, thebundle of light rays I03 which are directed to the cornea I04 of the observers eye, it will be noted-that the said rays will be returned as illustrated at I05 into the focusing system 42 of the camera. The focusing system; which in this particular-instance comprises a short focusing lens 42, will focus the said rays I05 on to the film 32, as illustrated at I06.

The focusing lens 42 is of such power andis so positioned relative to the eye, and the film is supported at such a distance relative to this position, that when the eye is carried through its successive minute movements during reading, the said movements will be greatly magnified so that it may be easily distinguished on the film; This short focus lens thereby enables the magnifying of the minute movements of the eyes without the necessity of having a relatively long light chamber and is greatly responsible for the great reduction in size of the instrument embodying our invention.

The light rays I05 reflected from the cornea are .illustrated as originating from the virtual focal point I'I of the corneal surface I04. The light rays I03 striking the surface of the lens I02 will be reflected along the path of the dot and dash lines illustrated at I08 coming as from the virtual focal point I09. It will be seen that thestop opening 99 formed by the end of the tube 43 does not receive any of these light rays. It also is apparent that the light rays I which come to a focus as illustrated at H0 in a plane in front of the film, even if the stop opening 99 were not used, would not be focused in the exposed area of the film 32, which in this instance, is in the vicinity of the stop opening 98.

The reason, therefore, that the'light'rays reflected by the corrective lens I02 are not'focused on the film, is because of the angular relation of the cone of light I03 relative to the axis of the focusing system and to the line of sight of the eye viewing the reading matter at 13. For example, if the light source 65 were nearer the axis of the focusing means, the light rays reflected by the surface of the lens I02 'would be more nearly parallel with the light rays I 08 reflected from the surface of the lens and the said light rays I08 would thereby be directed to the exposed area of the film, as has been usual in the prior art.

By controlling the above angular relations We have made it possible to photograph through correction lenses without interference by said correction lens. To aid in bringing'about this result, it will also be noted that the stop openings 33 and 38 will greatly cut out extraneous-light rays reflected by the surface of the lens I02. The angle at which the plane of the lens is supported relative to the longitudinal axis of the focusing system also plays an important part.

It will be noted that the head rest for supporting the head of the patient is in a vertical plane and that the axis of the focusing system is inclined downwardly relative to said vertical plane. This causes the reflected rays, as illustrated by the lines Iii and H2, to be directed atv a reater angle relative to the axis of the focusing means. The image focused at I I0 will thereby be further away from the exposed area of the film 32.

It will be. notedthat due .to the particular arrangement. for supporting the head of the patient and the angular tilt of the photographic instrument, the eyes look through the lower portions of the lenses so that in instances where bifocal or multifocal. lenses are used having specially corrected reading fields, the movements of the eyes maybe photographed through said fields.

. The film 32 is preferably moved at a constant predetermined speed during the photographing so that the speed .of reading may be calculated by the number of Words in the lines exposed and the time of said exposures.

It is also pointed out that the diameter of the lens-52 as compared with the correction lenses I02 is very small. This also eliminates the entry of extraneous light rays into the focusing system of the camera.

It is to be understood that the above Figure 13 is diagrammatic and is used herein only to illustrate the function of the device embodying our invention.

If in cases of corrective lenses of unusually high surface powers (high curvatures) lens refiections should enter the focusing system and be brought into the exposed area of the film, slight re-adjustment of the patients glasses by tilting or sideadjustment of the focusing system assures their total elimination.

The angle of the mirror l5'is such that the operator can observe the images therein through the ground glass 18' which covers the opening I0. By grasping the-tubes 43, which carry the lenses 42, one in each hand,- the operator can readily focus the images directly on to the cen ter "of the mirror, observing said images on the glass I8 during-the adjusting. The mounting of the lenses is an important feature of the machine for it permits a quick, easy and simple adjustment to be made manually without the use of 'gears or mechanical means. When the adjustment of the lenses is made, the panel 19 is slid rearwardly to cover the opening. This slidingaction swings the mirror upwardly out of the way, due to the arm 8| carried by the knob on the panel engaging and swinging the rocker arm 11.

Th reflection from the eye is now focused directly on the film through the lenses. At this time the flap l3 of the card holder I0 (Figures 1 and 2) is swung upwardly and the card 12 held-by the rigid card holder H can now be observed by the person. At this point the motor is turned on and the film travels through the housing 25 from the feed reel 30 to the take-up reel 31. The person now reads the indicia on the card 12, his eyes having become accustomed to observing the card by his observance of the first card I3, and themovement of his eyes is recorded on the film. If there is any 'hesitancy or defects in his eyes during reading, it is clearly shown on the film.

It will 'be readily apparent that the coordination or lack of coordination of the eyes of the person will beshown up very distinctly by observing thedista-nce between the records of the individual eyes. Since the film is moved at a constant speed, the variation in the relative movements of the eyes will be shown as a function of time.

These records are very valuable in determining the type of refractive lenses necessary to relieve eye strain or the kind of orthoptic training whichcwill give the most beneficial results. Also such: a binocular record will show distinctly whichof the eyes is restless in case of nystagmus. If the binocular'record shows thatthe vertical lines of: each of the individual records are sub-L- "stantia'lly'parallel, this will indicate that the per'son'i's able to hold his eyes relatively fixed on each fixation point while if the vertical lines'are not parallel, the patient is suffering from overconvergence or underconvergence. It should be stated here that since each of the camera objectives consists in only one lens 42 and the film moves upwardly, the movement of the record on the film is opposite to the movement of the eye. It is also to be noted that if the persons eyes are easily fatigued, this will be shown up as a variation in the distance between the individual records'after the person is caused to read for aperiod of time.

The speed of travel of the film can readily be adjusted so that the time elapsed for the reading of the card can be ascertained by the length of 'fllm taken to record the reading. If it is desired to record more than one persons eye movements 'onthe same roll of film without removing the length of film of each recording immediately afterward, a spring-pressed plunger 9| is positioned' in the top of the housing 25 above'the drive sprocket 35 The sprocket has aradial central groove 92 and when the plunger is depressed the pointedlower end of said plunger passes through the film into the groove to punch avh'ole in the film. Thus, each time a recording of one persons eye is taken, the plunger is deiprssed, whereby a hole is made in the film.

Then,'after the entire roll of film is used each recording is separated by a hole in the film.

, If it is desired to'remove each recording immediately after taking, a sliding blade 93 is provided on top of the take-up reel box 36 (Figure 2).

This blade is arranged to slide over the opening 36" in the top of the box and it is obvious that when film is passing through this opening the sliding of the blade will cut the film. The box 36 may then be removed from the compartment 28 andthe recorded film developed. The box is then returned to the compartment and the film again'wound on the winding reel, ready for feed roller an indicator 94 (Figures 2 and 5) is secured. on the outer end of a rock shaft 95, which is positioned in the lower front end of the compartment 29. The rock shaft carries an elongated" arm 9'0 which is held in constant en- 1 gagementwith the film roll 32 by a spring 91 se- 1' useful; however, we desire it understood that w the invention is not limited to such exact details of construction, because it is manifest that changes and modifications may be made, within the scope of the appended claim, without departing from the spirit of the invention.

- Having described our invention we claim:

1 In a device for photographically recording movements of each of the eyes of an individual simultaneously, the combination of means for j the next recording.

For ascertaining the amount of film on the;

locating the head of the individual in a given position, means for directing a beam of light onto the corneas of'the eyes at said given position to produce light reflections from said corneas, a dark chamber, light sensitive means supported for movement in said dark chamber and for exposures of separate portions thereof to the light reflected from the respective corneas, said dark chamber, on the side thereof toward the individ ual, having. a relatively flat wall'with spaced openings therein aligned substantially with each of the respective eyes of the individual, tubular members in said openings comprising telescoping parts supported for longitudinal movement relative to each other, one of each of said parts having'a focussing lens therein and the other having a relatively flat surrounding disc-like flange portionprotruding outwardly thereof in a direction substantially normal to the longitudinal axis of said part and of a diameter greater than the diameter of the openings in the relatively flat wall of the dark chamber and disposed in the rear of the inner surface of said wall adjacent the respective openings, perforated plates'spaced from said flat wall and each engaging a respec-' tive disc-like flange portion on the side thereof opposite the wall, resilient means for urging said perforate plate into frictional side surface rela tion. with the disc-like flange portion, said resiliently urged perforate plate providing. slide means forsupporting said disc-like flange pora side wall thereof, a light receiving screen in said opening, light reflective means pivotally supported internally of the. said housing for receiving light from said light focusing means for directing it onto said screen, said reflective 'portion-of the reflective means being spaced relative to the screen a distance substantially equal to thespace between the exposed portions of said light sensitive means and said reflective portion of the reflective means whereby the light may be initially focused on said screen, the said reflective 'means being movable to close said window opening and. to allow the focussed light to reach the light sensitive means, eye fixation means supported externally of the dark chamber for exposure to the eyes to bring about bin-ocular movements of the eyes while viewing the same and means for moving the light sensitive means when receiving said corneal reflections when the eyes are viewing said fixation means to record the displacements of the images of the light reflected from the corneas substantially in the plane of the moving portions of the light sensitive means caused by the respective eyes during the

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