US2573464A - Method and machine having application in pupillography - Google Patents

Description

00L 1951 0. LOWENSTEIN EAL 2,573,454

METHOD AND MACHINE HAVING APPLICATION IN PUPILLOGRAPHY Filed Aug. 6, 1948 6 Sheets-Sheet 1 INVENTOR arm ZoWENJrE/N 11?, ENE Z orwavrew BY [RIC KLHPPE Oct. 30, 1951 o. LOWENSTEIN ET AL 2,573,464

METHOD AND MACHINE HAVING APPLICATION IN PUPILLOGRAPHY Filed Aug. 6, 1948 6 Sheets-Sheet 2 III"! I I INVENTOR 0110 Lowe/vsrEnv BY Lea/v6 laswavnzw 0 ERIC kLflPPEk ATTORNEYJ Oct. 30, 1951 o. LOWENSTEIN ETAL 2,573,464

METHOD AND MACHINE HAVING APPLICATION IN PUPILLOGRAPHY TIME AXIS INVENTOR BY IRENE laevvem ew 1951 o. LOWENSTEIN ET AL 2,573,464

METHOD AND MACHINE HAVING APPLICATION IN PUPILLOGRAPHY Filed Aug. 6, 1948 6 Sheets-Sheet 4 INVENTOR Get. 30, 1951 o. LOWENSTEIN ET AL 2,573,464

METHOD AND MACHINE HAVING APPLICATION IN PUPILLOGRAPHY Filed Aug. 6, 1948 6 Sheets-Sheet 5 INVENTOR Orro lowwWE/N 0. LOWENSTEIN EI'AL MACHINE HAVING APPLICATION IN PUPILLOGRAPHY Oct. 30, 1951 6 Sheets-Sheet 6 METHOD AND Filed Au 6, 194a INVENTOR.

Orro lavvelvsre/N IRENE (oars/v Few R/c fim pao latented Get. 30, 1951 METHOD AND MACHINE HAVING APPLICA- TION IN PUPILLOGRAPHY Otto Lowenstein and Irene Loewenfeld, New York, and Eric Klapper, Orangeburg, N. Y. said Loewenfeld and said Klapper assignors to said Lowenstein Application August 6, 1948, Serial No. 42,768

3 Claims.

This invention relates to a method and apparatus for automatically measuring and plotting a series of images of varying sizes such as a series of images of the pupils of the eye.

The invention is particularly useful in the dia nostic procedures of pupillography. The method of pupillography has been described in many former publications of the present inventor, for example, Archives for Psychiatry 1927, pages 285-297 (German), The Physiology and Pathology of Pupillary Movements, Particularly in Schizophrenia (Berlin 1933); The Light Reflex of the Pupils in Syphilitic Lesions of the Central Nervous System (Basel, Switzerland, 1935); The Psychosensory Restitution Phenomenon (Basel, Switzerland 1937, German); Les Troubles du Rflexe Pupillaire a la Lumiere Dans Les Aiiections Syphilitiques du Systeme Nerveux Central (Paris 1939, French); Present State of Pupillography; Its Method and Diagnostic Significance. (With E. D. Friedman, Archives of Ophthalmology, volume 27.)

In short the method of pupillography comprises the steps of (1) taking a series of photographs of the pupils of the eyes under the influence of different stimuli, (2) thereafter measuring, plotting and/or drawing a curve of the pupil diameters of the eyes as they were affected by the stimuli and (3) then comparing the resultant curve or graph with the curve or graph of the normal reaction or with the curve or graph of certain known abnormal reactions.-

In taking the series of photographs the apparatus must be devised to provide for sharp clear photographs of each eye. Each of the eyes must be focused separately by separate optical systems since some patients hold their head at a slight angle and since some patients have one eye which is more deeply set in the orbit than the other. Since the horizontal eye spacing is different for different individuals it is also necessary to make the space between the optical systems adjustable. Two conflicting factors make the photographing diflicult: On the one hand, the two optical systems must be brought close together so as to obtain the images of the two eyes close to each other. On the other hand, the photographing must be done rapidly With infra red light and infra red sensitive film so that lenses of large diameter (or in other words lenses with a small focal ratio or f-number) are very essential to obtain the required exposure of the film.

Heretofore, in the plotting of the curves, it has been necessary to manually measure the 2 diameter of each pupil in each of the pictures taken. In the measuring of the eyes an accuracy of about 99.25% is necessary to make a satisfactory diagnosis.

It is an object of this invention to provide a method and apparatus for automatically and accurately producing a plot of the series of pupil diameters.

Another object of this invention is to provide a method and apparatus for measuring and plotting the various diameters of the pupils recorded on a series of photographs.

Another object of the invention is to provide a method and apparatus for automatically measuring and photographically plotting the diameters of a series of pupil images.

Another object of the invention is to provide a method and apparatus for automatically measuring and photographically recording the plots of the diameters of the pupils in a series of images of the two eyes in such a way that the recorded plots of the variations in diameters of the two eyes are superposed and can be distinguished from each other.

These objects and others ancillary thereto are obtained by taking the series of pictures of the eyes by means of a camera which has two closely spaced photographic objectives which are separately adjustable toward and away from the eyes for focusing and are also adjustable laterally with respect to each other. In order to employ large lenses (with a small f-number) as objectives the adjacent edges of the two lens objectives may be cut away or the lenses may be placed at a slight angle to each other. step the diameters of the images of the eyes obtained by the first step are obtained by a process and apparatus which causes a photoelectric cell to scan the images of the pupils and provides a means for measuring and recording the diameters of the pupils as measured by the photoelectric cell and scanning means. The scanning is obtained by employing a projector to project In the second sudden application of voltage, as the image of the pupil enters the slit, causes the single sweep to be triggered. The trace is thus started in a deflected position and remains deflected until the opposite pupillary border is reached, when the voltage disappears and the traceconsequent- 1y drops down, so that the sweep is completed in its zero position. A photograph of a small part of the downward moving portion of the trace on the oscilloscope represents the diameter ,of each pupil and the photographs of the series of downward traces may be taken on specially prepared film or paper so that the changing diam: eter of the pupil can be read directly from this photograph.

In preparing the first set of photographs from the eyes of the patient infra-red light and intrared sensitive film is preferably employed. The human eye is least sensitive to this type of light and where additional light is to be employed as the stimulus, .a green light to which the human eye most sensitive and to which the infra-red film is :least sensitive is effective. Large lens objectives are employed for the camera and these should be made separately adjustable in at least two directions, i. e., toward and away from the eye and laterally. The adjacent edges of the lenses can be ground off to permit the lenses to be moved close together to obtain a photograph with the image of the two eyes close together.

In the measuring of the pupil diameter the unsettling influence of the light passed by the iris of the eye interferes with the proper measurement of the pupil, because it constitutes a variable value. In patients with blue eyes which reflect less infra-red light than brown eyes, the iris will appear lighter on the film. Thisreduces the contrast between the iris and pupil portions of the picture. In case of a very light iris, its va ue ma he s hig hat t e S ngl sweep i ac ual y tri r d b the is and wh n i a effort to prev t t is the nQhrQhQu in O the oscilloscope is reduced, the .value of. the pupil ill also fai to tri t e sweep- In rd r to ov rteh e this eff c me ns p app in a count olta e t t ou p t pi he h toe e i c l and a rectifier-trigger circuit is provided so that the trig e nt of the pho oelec c c l can h adjusted for each individual set of photographs.

To ob n a erm nen l of e ri on in diameters .of the pupils, a camera is arranged to take a picture of small portion of the downwere a of e tr te he os i osco e.- S i able means are provided to differentiate the alternate images so that the m tor right and left eyes can be distinguished.

The novel features characteristic of this inven tion are set forth with particularity in the appended claims. The invention itself, however, both as 'to its organization and its method of opera io og e w h addi io al O iQQ-iS an advantages thereof, will best be understood from the following description of specific embodiments W13! 9 in 9 mm? wi h th c om n n draw ngs i h;

Figure 1 is a perspective .Yieyv illustrating how he pi u es of the es. a e ak n- .Fieiire 3 a d a ramma ic sho in o t e optical system of the camera.

Figure 2A is ,a perspective Yiew of the mountin fo he o ject ve lenses. f he Fi ure 2B is a dia rammat c view of the two nses in a cameras owip how the lar e nse (with small f-numherap having the adjacen s des cut away can be employed to take the pictures of the eyes.

Figure 2C is a diagrammatic view of a modified optical system employing large lenses which however are placed at an angle to the horizontal.

Figure 3 is a view of the film containing a se ies o ima es of t eyes.

Figure 4 is a diagrammatic plan view of the apparatus for measuring the sizes of the pupils.

fi ure {1A is a detail view of the rotating mirr.o r of Fig re 4.

Figure 5 i a view of the screen of the cathode ray 11 1 10 Figure 6A and 6B are views illustrating th response of the apparatus to the iris and pupil of the eye.

Figure '1 is a detail view showing the camera taking a picture of a portion of the screen of the cathode ray tube.

Figure 8 is a View of the plot obtained by the camera of Figure 7.

Figure 9 is a perspective view of a modified form of apparatus.

Figure 10 is a plan View of an apparatus similar to that of Fi ure 9 Figure 11 is a plan view illustrating another modified form of the apparatus.

Figure 12 is a detail view 9f the camera of Figure (i. I

Fi ure -1 il u trates ho t p et s are aken- The eyes 10 and ll) of the patientare illuminated by ra s pr je ted from li h sou c H an I contain the i ra ed f ters H an The pictures of the separate eyes l0 and I0 of the patient are taken by a camera l2 having two objectives !3 and M. A stimulus is applied to one or both Of the eyes of the patient by light source [5 and I6 which may contain green filters I5 and l 6. Usually onlyone eye at a time is stimulated by green light, for example, and the response of the p i s o the w eyes a e compared- In order to bring the photographs of the eyes close together the optical system shown diagrammatically in Figure 2 employed, The camera objective contains lenses l1 and I8. The eye II] is ima ed by lens I] at I9 and the eye I0 is ima ed by lens I! at 21. Similarly the eye I0 iS ima ed at .2 a th eye n at, 22 by t e lens (.8. Only the two inside images 19 and 20 are photographed by the film 25. A shield 103 extending from between the lenses H and I8 down to the film is provided to prevent any interference due to overlapping of the two images, etc. Asshown in Figure l, the mounting means for the ob ec i es s p ov d d w h a im a tin m n l3 for one objective which is adapted to move the objective 1; towards and away from the subject independently of the other objective l4 so that differences in the inset positions of the eyes of the patient, .ete. pan-be compensated for. The objective lilcontains an adjusting knob 14' which is adapted to move the objective M laterally with respect to the objective It so that patients having different pupillary distances may be photographed.

It is also necessary to adjust the apparatus to eo p ns e for pa ents ho t their heads- On ethod t com sa or hi tilt is y i t n h h e a Another met of c ensa n h em loy a sh wn i t mpd iie d vice o F ure 2A- he d ice o his figur not onl he ob e t ve 13 adj s able in and out by the focusing device [13' and jective system is rotatable so as to permit the objectives to be tilted to compensate for the tilting of the head of the patient. It is important for the patient to be at ease during the photographing process and if it is natural (or more comfortable) for a patient to tilt the head he must be allowed to do so.

Figure 2B is a detail view of the lenses of the two objectives shown in Figure 1 and illustrates how the lenses l1 and |8 are ground away at the adjacent edges H1 and H 8 respectively so as to permit employment of large lenses and yet obtain close spacing of the optical centers of the lenses.

An improved type of lens system and the optical path of the light rays is shown in Figure 2C. In the device of this figure the lenses I1 and I8" are tilted at a slight angle to the horizontal so that the images formed by said lenses will be closer to each other and more space is thus provided between the lenses l1" and IS".

The camera I2 is a motion picture type of camera and takes a series of negative images such as shown in Figure 3. This is the film from which it is necessary to obtain and plot the changing size of the diameters of the pupils. Heretofore the best method of measuring these diameters has been to project the picture on a screen to obtain a sharp, clear, large image and then measure and. plot the change in size of each pupil individually by hand.

Figure 4 shows diagrammatically one method and means for automatically measuring and plotting the sizes of the pupils according to the present invention. In this figure, the projector 30 projects the images of both eyes in rapidsuccession toward the stationary mirrors 3| and 32. A screen or shield 33 is placed between projector 30 and mirrors 3| and 32 so that the images of one eye only are projected onto mirror 3| and the images of the other eye only are projected onto mirror 32. Mirrors 3| and 32 are adjustably mounted so that they can be tilted or pivoted as shown in Figure 9. The images from mirrors 3| and 32 are directed toward a rotating mirror. As the mirror 3!; rotates it reflects first an image from mirror 3| and then an image from mirror 32, etc. The reflected images from rotating mirror 34 pass across a slit 35, and fall upon the photoelectric cell 31. The output of the photoelectric cell after being twice amplified and rectified is fed. to the oscilloscope. The rectifier is interposed between the second stage amplifier and the oscilloscope. A countervoltage is applied at 56' to the once amplified voltage of the photoelectric cell to bring the desired measuring point (immediately above the value of the iris) to ground potential. The rectifier cuts oiT voltages below ground potential and thereby eliminates the values of the iris.

The sudden shock necessary to trip the single sweep of the oscilloscope is therefore not produced directly by the difierence in density of the irisand pupil-portions of the image on the film, but is instituted when the rectifier starts conducting as soon as the voltage rises above ground; in other words, the rectifier acts as a trigger. This method is independent of the abruptness or contrast of the change in optical density.

Figures 6A and 6B illustrate how the iris and pupil of one eye may difier in photoelectric response from that of another eye. In these figures the portions of the projected film images which are passed by the screen 33 are shown at 50, 5|. In these images 52 and 53 represent a portion of the iris and 54 and 55 represent the pupils. Just below the images 50 and 5| in Figures 6A and 6B are illustrative traces produced on the oscillo scope when the respective images 50 and 5| are scanned by the photoelectric cell. The line 56 of Figure 6A shows the portion of the trace which: must be cut ofi to produce an accurate curve of the pupil and line 51 shows that a much larger countervoltage must be applied to cut oil the iris response of the eye image of Figure 6B than that of 6A. The countervoltage applied by means 56' must therefore be adjusted for the photographs of the eyes of each patient. The two eyes of the same patient may also photograph difierently or produce a difierent response as is illustrated by Figures 6A and 63 although generally the difierence in response will be much less for two eyes of the same patient than for the eyes of different patients. However, it is also necessary to adjust the countervoltage for each eye of the same patient. Since this difierence is less it has been found advantageous to adjust for the difference between two eyes of the same patient by adding a second countervoltage 51 to the twice amplified voltage as shown in Figure 4. The countervoltage 56 is applied to all responses of the photoelectric cell whereas the countervoltage 5'!" is applied to the responses of only the right or the left eye images. The time of applying the second countervoltage 51 is determined by the switch 84.

It is not necessary to see the height of the curve traced by the spot in the cathode ray tube since the downward movement of the spot measures the time required for the image of the pupil to be scanned by the photoelectric cell. It is essential to obtain a substantially square response curve, however, and this type of curve is obtained if the photographs of the pupils are sharp and clear, if the projector is properly focused, and if the proper counter voltages are applied, etc. A typical curve on the screen 59 of the cathode ray tube of a single sweep oscilloscope is shown in Figure 5. Since the speed of the single sweep is uniform, the time taken by the slit to cross the pupil is in direct proportion to the position of the descending branch of the trace on the face of the oscilloscope tube. By proper calibration, the descent is caused to occur at its proper point in reference to a coordinate system 58 covering the range of pupillary diameters.

The trace thus produced on the oscilloscope screen is recorded by means of a moving picture camera which is geared to the movements of the projector and the mirror. The camera aperture covers a narrow slit 6| across the middle of the oscilloscope tube.

The coordinate system is shown in the final photograph (Figure 8) as white lines on a grey background by faintly illuminating the face of the oscilloscope tube with a G. E. 6 watt fluorescent tube emitting light in the violet-ultraviolet range of the spectrum, and by painting the coordinate system black. It may also be caused to appear as dark lines on grey background by painting the lines with fluorescent paint onto the oscilloscope tube. The paint will fiuoresce when struck by the violet light, thus appearing dark on the record (Figure 9). The final trace (Figure 8) is thus produced on a sensitized band of film or paper, moving perpendicular to the slit-aperture of the recording camera, advancing intermittently and in step with the projector 30. It consists of a row of black lines, each representing one pupillary diameter, caused by the descending branch of the single sweep trace it crosses the center of the oscilloscope "tube covered by the aperture of recording camera 60. Two lines are recorded 'on film 6b (Figure8) one for-the right and one for the left pupil, each time the projector 353 and recording camera 60 areata-standstilL To d-iiferentiate between the traces representing the right and left pupilla-ry diameter, a semitransparent shutter par tly obscures the aperture of the recording camera while one pupil is meas ured and is open while the other pupil is measured." Because the picture to be covered by this shutter is long and thin, the shutter must also be long and thin. T-his can be accomplished various ways; one of which isillustrated in Fig ure 1 2 v A separate compartment I60 is located at the side of the camera 66 and contains the film movingmechanism, etc. The drive shaft I6-'I is connected to or is part of the main drive IBI for the whole apparatus which is driven by the motor 162. The shaft it! extends through the side =I53'into the camera '60 and contains an exc'en tr-ically mounted rod 169 which forwards the film intermittently. Connected to the shaft I 61 is a gear its which meshes with gear I55 which attached to shaft IE6. The shaft I66 is also another gear We which meshes with large gear IlI which drives the film transport roller I12. Also attached to the shaft F65 is a cam IN. The shaft IE6 is driven to' make one complete revolution when each pair of eye images is scanned. A lever Il is pivoted to the bearing element I68 at I15 and is adapted to be moved by the cam H3. Attached to the free end of the lever Ilt is a rod I76 which in turn is attached at the other end to a shutter moving means I80. The shutter moving rod I80 is pivotally attached to the side IE3 at ISI. the rod I39 that extends in front of the opening I82 of the camera Si: is the semi-transparent shutter means I33. A spring I84 is attached to the rod I8@ and tends to hold the lever I'M against the cam surface of the cam I73. It will be seen therefore that the cam I'I3 holds the semi-transparent shutter 5-83 away from the slot I82 for about /2 of each cycle so that the images of the trace which represents the diameter of either the right or the left eye as recorded on the film of camera 6!! are always darker than the images which represent the other eye.

Resetting the single sweep is done by a cam and microswitch which is synchronized with the remainder'of the apparatus in any suitable way. Figure 4A shows one sucharrangement in which two cams are attached to the shaft II! which rotates mirror 36. The mirror 31 has two mirror surfaces so that four eyes or two frames of the right and left eyes are scanned with each complete rotation of the mirror. The single sweep must be returned to its zero position by the resetting circuit (to ground potential'l four times with each revolution of the mirror- 34; The resetting cam ii of Figure 4A therefore has four projections l2, it, 74 and 75 cooperating with microswitch it to reset the oscilloscope. Above the cam 'II is shown the cam ll; This cam has two projecting quadrants wand-81 "and two -"i-ndented quadrants 82 and 83. Cam TI cooperates with microswitch 8d to apply the countervolta'ge 51' to the voltage developed by the images ofone of the eyes.

- Figures 9 and 10 show a modified form -of t'he Attached to the part of 8 apparatus which has some advantages over the device-of Figures 4 and 9. In the apparatus of these figures the scanning is obtained by a rotating-cylinder instead of the rotating'niir r'or 34, of Figures 4 and 4A. The rotating cylinder 85 contains a plurality (4 shown in Figure 10) of slits 86, 81, 88 and 89. These slots or slits are shielded from one side as shown at 90 and "S'I'in Figure '10. The shields from any two adjacent slits project in opposite directions so that the shieldeife'ctivel cuts oil? the light; com ing from one of the stationary mirrors SI, 32'. The'cylinder or drum 85 is rotatable on a shaft 92 so that images from the mirrors '3I and 32 are scanned alternately by the slits (-Figu 'ejlfl) Adjacent the outside edges of the slits 8649a pair of sharply honed blades I90, I9I are adjust ably mounted as by means I92, I93. A suitable lens system 93 directs the light rays passing the slits toward the photoelectric cell 37. Adapted to rotate'with the drum 85 are two cams II and TI. The cam lI' corresponds to cam ll of Figure 4A and acts with the switch I5 to reset the single sweep oscilloscope. The cam ll corresponds to cam "I1 of Figure 4A and cooperates with switch 84' to connect or disconnectthe counter E. F. which is to be applied at the second stage of amplification similar to the counter voltage means 51' of Figure 4. V

Figure 11 shows diagrammatically, another modified form of the invention in which the mirrors are eliminated. The drum 85' contains a number of slits 94, 95. The projector 30' is' adapted to project the images of the two eyes from two separate lens systems 96, 91. The light from each image is focused by a lens system 98 or- 99 is passed through a stationary shield I00 and is directed toward the photoelectric cell 3-! by prism IUI- or I02. Cams similar to cams TI, H or -'II", "-11" are attached to the shaft 92 to effect the resetting of the oscilloscope and control the proper counter voltage.

We claim:

1.The method of measuring automatically and registering graphically, a series of consecutive pictures 'or images of the pupils of the eyes on a transparent filmsuch as obtained by the method known'as' pupillography comprising the steps of projecting the images intermittently and sequeritially in the general direction of a slit. behind which is a photoelectric cell, causing the image to "be scanned by said slit at a uniform; speed bymovihg-the slit and image relative to to each other whereby the light establishes a.

a counter voltage device which is adjustable to eliminate undesirable low voltage reactions of the photoelectric cell, rectifying the resultant voltage and "feedingthe-rectified voltage to the direct input-terminal of a single sweep oscilloscope, resettingtheoscilloscope after each image has-been scanned whereby each scanned image of the transparent film traces a square wave on the screen of said oscilloscope, the downward portion of said wave -be'in pproportional to the time required for the pupil image to be scanned by said slit, photographing a part of each of the downward portionsof said'waves on an intermittently moved film of a photographic camera to obtain a plot in'which the position of the various photo: graphed-parts of the wave on the photograph is proportional tothediameter of the pupil scanned;

2. An apparatus for measuring automatically and registering graphically, a series of consecutive pictures or images of the pupils of the eyes on a transparent film such as obtained by the method known as pupillography comprising means for projecting the images intermittently and sequentially, a slit for scanning the images formed by the projecting means, a photoelectric cell behind said slit adapted to receive the light which passes through said slit, means adapted to move the image from the projecting means reative to said slit, means for amplifying the voltage developed by the light from said slit which falls on said photoelectric cell, means for applying a predetermined counter voltage to the amplified voltage, a single sweep oscilloscope adapted to be triggered by a small positive voltage, a rectifier for rectifying the voltage resulting from the combination of the amplified voltage and the counter-voltage the output of which is connected to the direct input terminal of said oscilloscope, means for resetting the oscilloscope after each image has been scanned, means for photographing a correspondin portion of each response curve which is traced on said oscilloscope.

3. An apparatus for measuring automatically and registering graphically a series of consecutive pairs of pictures or imagesof the right and left pupils of the eyes such as obtained by the method known as pupillography comprising means for projecting the pairs of images consecutively, a slit for scanning the images produced by said projecting means, a photoelectric cell behind said slit adapted to receive the light passing through the latter, two stationary reflecting means, one for each of the two projected right and left images of the pupils, a rotatable reflecting means intermediate said two stationary reflecting means so arranged as to reflect the images coming from the said stationary reflecting means across said scanning means when rotated, means for rotating said rotatable reflecting means at a uniform speed so that the said right and left images are moved across said slit consecutively at a uniform speed, means for amplifying the voltage developed by the light from said slit which falls on said photoelectric cell, means for applying a predetermined counter voltage to each of the amplifled voltages obtained from the images of the pupil of the left eye, separate means for applying a different predetermined counter voltage to each of the amplified voltages obtained from the right eye, a single sweep oscilloscope adapted to be triggered by a small positive voltage, a rectifier for rectifying the voltages resulting from the combination of amplified voltages and countervoltages the output of which is connected to the direct input terminal of said oscilloscope, means for resetting the oscilloscope after each image has been scanned, and means for photographing a corresponding portion of each response curve that is traced on the oscilloscope to graphically register the measured dimensions of the pupils.

OTTO LOWENSTEIN. IRENE LOEWENFELD. ERIC KLAPPER.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,132,520 Taylor et al. Oct. 11, 1938 2,184,131 Taylor Dec. 19, 1939 2,229,721 Brandt Jan. 28, 1941 2,445,787 Lilienield July 27, 1948

Images