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An apparatus for pupillography with intermittent infrared light
Journal of PsychosomaticResearch, 1961, \ol. 5, pp. 224 10 22h. Prrgamon PrcasLtd. Printed in Northern Ireland
AN APPARATUS FOR PUPILLOGRAPHY WITH 1NTERMITTENT INFRARED LIGHT* IWMAR
DUREMAN. TORKEL SC‘HOLANDER alld (Received
30 November
HENRY SALDE
1960)
INTRODUCTION DURING recent years the continuous registration of pupillary reactions to different external and internal stimuli has been accomplished chiefly by using two diflerent principles, the photoelectric and the cinematographic. The former method was introduced by Malthesos in connection with animal experiments and has been improved and developed by MATTHES (1941) and C~PPEKS (1951, 1954) for use in investigations with human beings. A similar method has been used by Russian scientists ATAEV (1953) and GLEZER (1953). The foremost exponent for the cinematographic method has been L~VENSTEIN (1942), who during more than thirty years of research has built up a large. complicated and very expensive apparatus.+ MactiEhleR (1941). and more recently PEERSEN, (1956) have simplified the method and tried to make it more adaptable to clinical use. His monograph is recommended for a more detailed historical survey. Common to the methods mentioned here is the use of infrared illumination of the eye. which does not affect the pupil. Registration can thus occur even in the dark. Thephotoelectric method is built on the changes in the amount of reflected infrared light which is brought about by changes in pupillary size. These changes are then registered directly on paper or a film by means of a photocell. Thus. one obtains here an immediate and continuous registration of the course of the reactions. On the other hand, no information is obtained on the absolute size of the pupil. Neither is it possible to follow irregularities in the form and concentricity of the pupil during its course of movement. Thus, even though the method has many advnntagcs because of the direct and continuous reading of the disadvantage that quantitatively pupillary reactions. this dncs not. in its present form, outweigh it is not correct. By menns of cinr,firrtc!:l,up/~ic registration a relatively accurate absolute measurement of the pupil is obtained, and it is also possible to follow any subsequent deviations in form and movement. The method is certainly not continuous. but since the film can be speeded LIP to 100 pictures per sec. in reality this makes little diffcrencc.
From the beginning WC have endeavoured to work out a relatively simple and easy method which would involve the least possible discomfort for both the subject and the cxperitnenter. Finally. there should also be possibilities for synchronizntlon \vith other recordings of autonomic functions. The last named prc-requisite soon forced us to give up the current cinelnatographic methods because of insurmountable diffkultics. Instead we have construAcd an apparatus with intcrmittcnt infrared illumination produced by a stroboscope. The film runs continuously \vithouT a shutter. with the help of two aynchroiimot~)rs. * ):,-omIIWPsvcholo+;l
Lahol-alot-!,
Dep;~rtmcnt
9 D~jr,nc the Final 17rc~x1rotion of 1111, milnu\cl-il:l
of P\qchiair!.
LJn~\~r>ltv of Lp@lr, S\\cd,:t~. f01- puhlic~~t~on wc Iurned th;tt ;i ncbb dcvux
li)i-
An apparatus
for pupillography
with intermittent
infrared
light
225
There are many advantages with such a device; one is that both the stroboscope and the camera can be steered by the same timer which can even start possible simultaneous recordings, another is that there is no difficulty with the marking of time. APPARATUS The apparatus consists of two parts: (i) tine-camera [with a propelling device for the film], (ii) stroboscope and timer [with infrared flashtubes]. The camera is shown open in Fig. I. It is mounted on an arm extending from a stable stand, which permits raising and lowering as well as swinging and displacement sideways. The camera is attached to a table with casters and can be moved toward and away from the subject(S) who sits in a comfortable chair with his head on a specially constructed head-rest which supports the head as firmly as possible without being uncomfortable. A little red twinkling bulb (1) on an adjustable holder attached to the camera, at a distance of 72 cm from S, serves as a fixation point. A simple sighting device permits S to control the focus during the experiment. The camera box is made of plywood which has been lined with aluminium foil, and is painted black inside. The 35 mm film runs from a light-proof casette (2) and is driven continuously by a rubber spool with two synchronmotors (3). By means of an electromagnet (4) one can, either manually or via a timer, hold firmly or release the propellent rubber spool. The speed of the film is adjusted according to the preferred speed of exposure. The two objectives (S), 80 mm Zeiss Tessar 1-2. 8, are mounted side by side on moveable plates, thus permitting an adjustment which corresponds to the distance between the pupils. The film runs horizontally, and when both eyes are photographed the objectives are placed so that the eyes are reproduced each on its half of the film. When photographing one eye, only one-half of the film is used and after it has been turned in the dark the other half can be exposed. Precision focusing has been solved with a mirrorvisor device (6) so that the picture is thrown by way of a mirror upon a ground-glass at the time of focusing. Small, round, mutually displaced prisms are inserted in the ground glasses. These serve two purposes, viz. that of exact focusing, and that of correct placement of each eye on its half of the film. In focusing, the camera is moved until both eyes are in the right position and are reproduced sharply without breaks of the contours in the prism-sight. This distance is corrected for infrared wave length (PETEKSEN pp. 102-103). While photographing the mirrors are pressed up by means of a catch. Exposure takes place with two Sash-tubes (7) which are coupled in series and are driven by a stroboscope with a very high output. When the frequency of exposure is pushed up towards 100 pictures per second, practical problems arise in connection with overheating. Thus it is necessary to arrange for air or liquid cooling of the flash-tubes. Moreover with such high speeds the voltage in the stroboscope must be much increased. If the condensers are not allowed to charge sufficiently between each flash, the result will obviously be a reduction in the light-intensity. With frequencies around 25-30 pictures per second, however, the generation of heat becomes negligible, during shorter periods of recording. The flash-tubes are mounted in adjustable projectors and equipped with a Kodak infrared filter no. 87. This effectively filters out waves shorter than 740 m/c, and the remaining infrared light does not affect the pupils. The film used is Kodak infrared super sensitive. Up to this time reading of the films has been accomplished by means of a projector, which enlarges each picture to ten times its original size. SUMMARY
An apparatus for pupillography which is simple and easy to handle and therefore adaptable to practical clinical purposes is described. The registration is cinematographic, but the film runs continuously without a shutter with the help of two synchronmotors. The infrared illumination is intermittent and produced by a stroboscope. AcknowlerlRernents-Fredrik Backlund, M.A. and our technician Martin Juhlin have managed the construction of the apparatus. Without their invaluable assistance and never failing interest this work would have been impossible. Our work has been supported by grants from the Swedish Medical Research Council. A special
226
INGMAR
DUREMAN,TORKELSCHOLANDERand HENRY SRLDE
grant given to one of us (Dureman) by the Vasteras Board of Culture made it possible to make invaluable direct contacts with German experts on pupillography. The subsequent refinement of the method through experiences obtained during large-scale practical application would have been impossible without generous support from the Swedish Malt Beverages Research Council and Syster ThanelI’s Fund for Psychiatric Research. REFERENCES ATAEV M. M. (1953) A method for simultaneous recording of pupillary reactions and E.E.G. during conditioning in man (in Russian). Sechrnov J. Physiol. 39, 622. CXPPERSC. (1951) Eine neue Methode zur stetigen Registrierung der konsensuellen Pupillenreaktion Klin. Mbl. Augenheilk. 119, 411. CXPPERS C. (1954) Die fortlaufende Registrierung der direkten und der konsensuellen Pupillenreaktion. Y. Gvuefes Arch. Augenheilk. 155, 588. GLEZERV. D. (1953) Contraction of the pupil by conditional reflex (in Russian). Sechenou J. Physiol. 39, 571. L~WENSTEIN0. and FRIEDMANE. D. (1942) Pupillographis studies. I. Present state of pupillography; its method and diagnostic significance. Arch. Ophthal. IV. Y. 27, 969. MACHEMERH. (1933) Eina kinematographische Methode zur Pupillen-messung und Registrierung der Irisbewegung. Klin. Mbl. Augenheilk. 91, 302. MALTHESOSC. (1939) Eine Methode zur fortlaufenden Registrierung der Pupillenweite. Arch. Physiol. 241, 129. MATTHESH., MATTHESK., BRUNNW. and FALK R. (1941) Untersuchungen iiber die Pupillenreflexe beim Menschen. Pjfiigers Arch. ges. Physiol. 244, 644. PETERSENP. (1956) Die Pupillographie und das Pupillogramm, Eine methodologische Studie. Acta Physiol. &and. 37, Supplement 125. pp. I-141 YOUNG F. A. and BIERSDORFW. R. (1952) An apparatus for taking rapid photographs of the pupil in visual darkness. Amer. J. Psycho/. 65, 617.
AN APPARATUS FOR PUPILLOGRAPHY WITH 1NTERMITTENT INFRARED LIGHT* IWMAR
DUREMAN. TORKEL SC‘HOLANDER alld (Received
30 November
HENRY SALDE
1960)
INTRODUCTION DURING recent years the continuous registration of pupillary reactions to different external and internal stimuli has been accomplished chiefly by using two diflerent principles, the photoelectric and the cinematographic. The former method was introduced by Malthesos in connection with animal experiments and has been improved and developed by MATTHES (1941) and C~PPEKS (1951, 1954) for use in investigations with human beings. A similar method has been used by Russian scientists ATAEV (1953) and GLEZER (1953). The foremost exponent for the cinematographic method has been L~VENSTEIN (1942), who during more than thirty years of research has built up a large. complicated and very expensive apparatus.+ MactiEhleR (1941). and more recently PEERSEN, (1956) have simplified the method and tried to make it more adaptable to clinical use. His monograph is recommended for a more detailed historical survey. Common to the methods mentioned here is the use of infrared illumination of the eye. which does not affect the pupil. Registration can thus occur even in the dark. Thephotoelectric method is built on the changes in the amount of reflected infrared light which is brought about by changes in pupillary size. These changes are then registered directly on paper or a film by means of a photocell. Thus. one obtains here an immediate and continuous registration of the course of the reactions. On the other hand, no information is obtained on the absolute size of the pupil. Neither is it possible to follow irregularities in the form and concentricity of the pupil during its course of movement. Thus, even though the method has many advnntagcs because of the direct and continuous reading of the disadvantage that quantitatively pupillary reactions. this dncs not. in its present form, outweigh it is not correct. By menns of cinr,firrtc!:l,up/~ic registration a relatively accurate absolute measurement of the pupil is obtained, and it is also possible to follow any subsequent deviations in form and movement. The method is certainly not continuous. but since the film can be speeded LIP to 100 pictures per sec. in reality this makes little diffcrencc.
From the beginning WC have endeavoured to work out a relatively simple and easy method which would involve the least possible discomfort for both the subject and the cxperitnenter. Finally. there should also be possibilities for synchronizntlon \vith other recordings of autonomic functions. The last named prc-requisite soon forced us to give up the current cinelnatographic methods because of insurmountable diffkultics. Instead we have construAcd an apparatus with intcrmittcnt infrared illumination produced by a stroboscope. The film runs continuously \vithouT a shutter. with the help of two aynchroiimot~)rs. * ):,-omIIWPsvcholo+;l
Lahol-alot-!,
Dep;~rtmcnt
9 D~jr,nc the Final 17rc~x1rotion of 1111, milnu\cl-il:l
of P\qchiair!.
LJn~\~r>ltv of Lp@lr, S\\cd,:t~. f01- puhlic~~t~on wc Iurned th;tt ;i ncbb dcvux
li)i-
An apparatus
for pupillography
with intermittent
infrared
light
225
There are many advantages with such a device; one is that both the stroboscope and the camera can be steered by the same timer which can even start possible simultaneous recordings, another is that there is no difficulty with the marking of time. APPARATUS The apparatus consists of two parts: (i) tine-camera [with a propelling device for the film], (ii) stroboscope and timer [with infrared flashtubes]. The camera is shown open in Fig. I. It is mounted on an arm extending from a stable stand, which permits raising and lowering as well as swinging and displacement sideways. The camera is attached to a table with casters and can be moved toward and away from the subject(S) who sits in a comfortable chair with his head on a specially constructed head-rest which supports the head as firmly as possible without being uncomfortable. A little red twinkling bulb (1) on an adjustable holder attached to the camera, at a distance of 72 cm from S, serves as a fixation point. A simple sighting device permits S to control the focus during the experiment. The camera box is made of plywood which has been lined with aluminium foil, and is painted black inside. The 35 mm film runs from a light-proof casette (2) and is driven continuously by a rubber spool with two synchronmotors (3). By means of an electromagnet (4) one can, either manually or via a timer, hold firmly or release the propellent rubber spool. The speed of the film is adjusted according to the preferred speed of exposure. The two objectives (S), 80 mm Zeiss Tessar 1-2. 8, are mounted side by side on moveable plates, thus permitting an adjustment which corresponds to the distance between the pupils. The film runs horizontally, and when both eyes are photographed the objectives are placed so that the eyes are reproduced each on its half of the film. When photographing one eye, only one-half of the film is used and after it has been turned in the dark the other half can be exposed. Precision focusing has been solved with a mirrorvisor device (6) so that the picture is thrown by way of a mirror upon a ground-glass at the time of focusing. Small, round, mutually displaced prisms are inserted in the ground glasses. These serve two purposes, viz. that of exact focusing, and that of correct placement of each eye on its half of the film. In focusing, the camera is moved until both eyes are in the right position and are reproduced sharply without breaks of the contours in the prism-sight. This distance is corrected for infrared wave length (PETEKSEN pp. 102-103). While photographing the mirrors are pressed up by means of a catch. Exposure takes place with two Sash-tubes (7) which are coupled in series and are driven by a stroboscope with a very high output. When the frequency of exposure is pushed up towards 100 pictures per second, practical problems arise in connection with overheating. Thus it is necessary to arrange for air or liquid cooling of the flash-tubes. Moreover with such high speeds the voltage in the stroboscope must be much increased. If the condensers are not allowed to charge sufficiently between each flash, the result will obviously be a reduction in the light-intensity. With frequencies around 25-30 pictures per second, however, the generation of heat becomes negligible, during shorter periods of recording. The flash-tubes are mounted in adjustable projectors and equipped with a Kodak infrared filter no. 87. This effectively filters out waves shorter than 740 m/c, and the remaining infrared light does not affect the pupils. The film used is Kodak infrared super sensitive. Up to this time reading of the films has been accomplished by means of a projector, which enlarges each picture to ten times its original size. SUMMARY
An apparatus for pupillography which is simple and easy to handle and therefore adaptable to practical clinical purposes is described. The registration is cinematographic, but the film runs continuously without a shutter with the help of two synchronmotors. The infrared illumination is intermittent and produced by a stroboscope. AcknowlerlRernents-Fredrik Backlund, M.A. and our technician Martin Juhlin have managed the construction of the apparatus. Without their invaluable assistance and never failing interest this work would have been impossible. Our work has been supported by grants from the Swedish Medical Research Council. A special
226
INGMAR
DUREMAN,TORKELSCHOLANDERand HENRY SRLDE
grant given to one of us (Dureman) by the Vasteras Board of Culture made it possible to make invaluable direct contacts with German experts on pupillography. The subsequent refinement of the method through experiences obtained during large-scale practical application would have been impossible without generous support from the Swedish Malt Beverages Research Council and Syster ThanelI’s Fund for Psychiatric Research. REFERENCES ATAEV M. M. (1953) A method for simultaneous recording of pupillary reactions and E.E.G. during conditioning in man (in Russian). Sechrnov J. Physiol. 39, 622. CXPPERSC. (1951) Eine neue Methode zur stetigen Registrierung der konsensuellen Pupillenreaktion Klin. Mbl. Augenheilk. 119, 411. CXPPERS C. (1954) Die fortlaufende Registrierung der direkten und der konsensuellen Pupillenreaktion. Y. Gvuefes Arch. Augenheilk. 155, 588. GLEZERV. D. (1953) Contraction of the pupil by conditional reflex (in Russian). Sechenou J. Physiol. 39, 571. L~WENSTEIN0. and FRIEDMANE. D. (1942) Pupillographis studies. I. Present state of pupillography; its method and diagnostic significance. Arch. Ophthal. IV. Y. 27, 969. MACHEMERH. (1933) Eina kinematographische Methode zur Pupillen-messung und Registrierung der Irisbewegung. Klin. Mbl. Augenheilk. 91, 302. MALTHESOSC. (1939) Eine Methode zur fortlaufenden Registrierung der Pupillenweite. Arch. Physiol. 241, 129. MATTHESH., MATTHESK., BRUNNW. and FALK R. (1941) Untersuchungen iiber die Pupillenreflexe beim Menschen. Pjfiigers Arch. ges. Physiol. 244, 644. PETERSENP. (1956) Die Pupillographie und das Pupillogramm, Eine methodologische Studie. Acta Physiol. &and. 37, Supplement 125. pp. I-141 YOUNG F. A. and BIERSDORFW. R. (1952) An apparatus for taking rapid photographs of the pupil in visual darkness. Amer. J. Psycho/. 65, 617.