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Color Fields Condemned
556
EDITORIALS
broad, upward conjunctival bridge. This bridge, held by fixation forceps, gives good control of the eye during the operation. Afterwards it gives a better coaptation of the lips of the corneal incision. It also furnishes a broad vascular supply for the corneal flap. This is an elaboration of the cataract operation worthy of the attention of other operators. Other lectures, given by local instructors, with demonstrations before sections of the class, and round-table-discussion luncheons, filled out the course. It was arranged so that most of the first week was devoted to ophthalmology, the second week to otolaryngology. The last days were allotted to a meeting of the Western Section of the "Triological" Society, at Santa Barbara. Wednesday, January 26th, the course being given over to otolaryngology, the Western Ophthalmological Society held its annual meeting. "Disturbances of the vertical motors of the eye" by Professor Bielschowsky opened the program. "A report on seventy-five cases of sympathetic ophthalmitis observed at the Massachusetts Eye and Ear Infirmary" was read by Dr. Rodman Irvine; and one on "Contact glasses," by Dr. John P. Lordan of Los Angeles. In the afternoon there was a symposium upon uveitis, opened by papers on pathological aspects, by Dr. M. M. Beige1man; tubercular etiology, by Dr. H. G. Merrill; and focal infections, by Dr. W. B. Boyce. Probably the Western Society will meet in connection with the Midwinter Course next year. Edward Jackson COLOR FIELDS CONDEMNED The steadily increasing importance of critical study of the visual fields in the problem of cerebral localization has led on the one hand to greater refinement in the study of the white fields and on
the other hand to a renewed emphasis on the significance of the color fields. We have also come to attach a larger importance to perimetry and campimetry in regard to lesions of the optic nerve and retina and in dealing with the progress of glaucoma. It cannot, however, be said that there is universal agreement as to the relative value of various methods of visual-field study. As to the significance of changes in the white field there has been little question; but there have always been some who doubted the dependability of findings as to the color fields. Some still believe that the taking of the color fields is an essential part of perimetric investigation; while others maintain that accurate study of the fields for white will disclose every fact which can possibly be learned from comparison of the color fields. The mechanism by which visual impressions are received and transmitted to the brain centers is hardly less a mystery today than when it was pondered over by Young or Helmholtz. We know that the retina transforms vibrations into nerve impulses, and there seems no great difficulty in appreciating that stronger stimuli should give rise to sensations of greater brightness. But shall we ever know, rather than theorize, concerning the means by which different wave lengths are interpreted as variety of color? To most of us it would probably seem natural to suppose that the vibrations which we perceive as color are conveyed impartially by each nerve fiber from the eye to the brain. Furthermore, one might suppose that damage to a single fiber would affect alike its capacity for conveying the individual wave lengths (corresponding to different colors) and for conveying the sum total of those wave lengths (from which we derive the impression of white light). Some such point of view is inherent in
EDITORIALS
557
the criticisms offered by Magitot and ous difficulties. Hue varies with intensity Dubois- Poulsen (Annales d'Oculistique, of illumination. Most investigators have 1937, v. 124, p. 649) under the title abandoned colored lights in favor of "Condemnation of colored test objects." colored papers. Because the exact characIn favor of the taking of. color fields ter of the illumination changed the zone it has been argued that the procedure en- within which the different colors were larges scotomata and renders them more perceived, it was proposed to make the manifest; the diameter of the blind spot tests in full daylight, with the eye preof Mariotte, for example, being increased adapted. It was shown by Alajmo that one fourth with a red as compared with a in these conditions the blue and yellow white test object. It is believed that de- fields coincided and that the red field was fects can be discovered earlier with the 10 degrees larger than the green. There colored objects than with a white object. further remain the problems of obtaining But this apparent advantage of the papers whose colors would be constantly color method is unfortunately neutralized fresh, and winter days as clear as sumby inconveniences, some of which are mer days! Magitot and Dubois-Poulsen characterinstrumental, others attributable to the ize as false the long-cherished belief that patient. The constancy of the results obtained the fields for colors are narrower than depends on the size of the test object, its those for white. "The peripheral achrocontrast with the background, its hue, matopsia of Landolt and Charpentier is an erroneous notion." As a matter of. fact, and the intensity of the illumination. Colored test objects must be relatively the color fields may extend almost as large. Using the gray background recom- far as the field for white. Wentworth mended by Engelking, Ferree, and Rand, obtained this result by using spectral and others, red and green are perceived colors of sufficient intensity; Feree and over a much larger field than on a black Rand, and also Gaudissart, by increasing ground, for the reason that the largest the illumination. With sufficient illuminacolor fields are obtained in the absence tion, green may be perceived as far at the periphery as white. of contrast. The inevitable conclusion is that color It is easy to insure a uniform gray in the perimetric background, but uniformity perimetry as it is usually practiced and and permanence are far more difficult in reported can only be possible with colors regard to colored papers, discs, or balls, lacking purity and brilliancy. To every whose tendency to become dull is in pro- scotoma for color, declare Magitot and portion to the weakness of their color Dubois-Poulsen, there is a corresponding saturation. They must therefore be scotoma for white. Certain minor difficulties pertaining to changed frequently. The attempt to overcome this difficulty by using a luminous the patient are of definite significance but red spot is defeated by the fact that the may be neglected in practice. These inlight intensity of the spot should always clude (1) defects of color and light sense be the same, so that it is necessary to (estimated at 4 percent of the cases) ; (2) resort constantly to new bulbs, adequately the fact that the field for red is smaller standardized, and using an electric cur- in hyperopes and the field for blue dirent of constant strength. minished in myopes, whereas a narrow The two factors in chromatic quality, pupil enlarges the field in both categories namely, tint and luminosity, present seri- of ametropia; and (3) that age has more
558
EDITORIALS
influence in reducing the color fields than the white field. Of much greater importance is the psychic factor. The taking of a visual field taxes the patient's intelligence and power of attention. Evans has shown that fear may enlarge the blind spot. It is often difficult for a person of moderate intelligence to realize that he must at the same time see the test object and the fixation point, and in color perimetry there is added the further demand for correctly recognizing and naming the colored test objects. In short, color perimetry calls for more sustained attention than white. Fatigue may produce islands of amblyopia. Many patients have difficulty in maintaining their attention for longer than 10 minutes. The differences in color perimetry are extreme, and it is impossible to obtain complete standardization. The maximum and minimum figures obtained show wide variation. As contrasted with color perimetry, Magitot and Dubois-Poulsen point out that records of the fields for white have the requisite qualities of simplicity, precision, and constancy of results. This method must, however, be practiced with accurate consideration of all the factors involved. The size of the test object employed should vary according to the zone under examination. Accepting the words in their broad application, the authors quote with approval Moreau's saying that the peripheral field "guesses," the middle field "perceives," and the central field "sees." As a matter of clinical convenience Magitot and Dubois-Poulsen recognize three principal isopters: (I) peripheral, (2) middle, (3) central. With a gray background and constant illumination, and using the customary 33-centimeter are, they apply a 3-millimeter test object
to the zone outside the 3D-degree circle, and a I-millimeter object to the zone between 10 and 30 degrees. The central zone they suggest should be explored with the stereocampimeter, preferably using Evans' technique for angioscotometry. W. H. Crisp
PUBLIC-SCHOOL LIGHTING An interesting and valuable contribution to the science of proper lighting as it pertains to public schools was made by J. Fleischer and A. J. Hoffman in the Transactions of the Illuminating Engineering Society some two years ago. The information gleaned from their investigations should be in the hands of the opththalmological profession to answer the frequent questions. The work was performed in five different public schools in Chicago, involving 78 classrooms and 2,682 students in the fifth, sixth, seventh, and eighth grades. No special conditions were set up beyond the necessary equipment, which consisted of a portable kit so arranged that the lighting intensity on an inclined working plane could be varied from I to 400 foot-candles. The color and quality of the light remained constant, the intensity of illumination being the only variable. In the first trial, undiffused illumination was used, meaning that there was no diffusing medium between the light and the visual task. This was referred to as "undiffused lighting." In the second trial, a screen with good diffusing qualities that eliminated specular reflection was placed between the light and the visual task. The resulting illumination was referred to as "diffused lighting." The child was asked to read good black type on a good quality of white paper, 12-point type being used in the fifth and sixth grades
EDITORIALS
broad, upward conjunctival bridge. This bridge, held by fixation forceps, gives good control of the eye during the operation. Afterwards it gives a better coaptation of the lips of the corneal incision. It also furnishes a broad vascular supply for the corneal flap. This is an elaboration of the cataract operation worthy of the attention of other operators. Other lectures, given by local instructors, with demonstrations before sections of the class, and round-table-discussion luncheons, filled out the course. It was arranged so that most of the first week was devoted to ophthalmology, the second week to otolaryngology. The last days were allotted to a meeting of the Western Section of the "Triological" Society, at Santa Barbara. Wednesday, January 26th, the course being given over to otolaryngology, the Western Ophthalmological Society held its annual meeting. "Disturbances of the vertical motors of the eye" by Professor Bielschowsky opened the program. "A report on seventy-five cases of sympathetic ophthalmitis observed at the Massachusetts Eye and Ear Infirmary" was read by Dr. Rodman Irvine; and one on "Contact glasses," by Dr. John P. Lordan of Los Angeles. In the afternoon there was a symposium upon uveitis, opened by papers on pathological aspects, by Dr. M. M. Beige1man; tubercular etiology, by Dr. H. G. Merrill; and focal infections, by Dr. W. B. Boyce. Probably the Western Society will meet in connection with the Midwinter Course next year. Edward Jackson COLOR FIELDS CONDEMNED The steadily increasing importance of critical study of the visual fields in the problem of cerebral localization has led on the one hand to greater refinement in the study of the white fields and on
the other hand to a renewed emphasis on the significance of the color fields. We have also come to attach a larger importance to perimetry and campimetry in regard to lesions of the optic nerve and retina and in dealing with the progress of glaucoma. It cannot, however, be said that there is universal agreement as to the relative value of various methods of visual-field study. As to the significance of changes in the white field there has been little question; but there have always been some who doubted the dependability of findings as to the color fields. Some still believe that the taking of the color fields is an essential part of perimetric investigation; while others maintain that accurate study of the fields for white will disclose every fact which can possibly be learned from comparison of the color fields. The mechanism by which visual impressions are received and transmitted to the brain centers is hardly less a mystery today than when it was pondered over by Young or Helmholtz. We know that the retina transforms vibrations into nerve impulses, and there seems no great difficulty in appreciating that stronger stimuli should give rise to sensations of greater brightness. But shall we ever know, rather than theorize, concerning the means by which different wave lengths are interpreted as variety of color? To most of us it would probably seem natural to suppose that the vibrations which we perceive as color are conveyed impartially by each nerve fiber from the eye to the brain. Furthermore, one might suppose that damage to a single fiber would affect alike its capacity for conveying the individual wave lengths (corresponding to different colors) and for conveying the sum total of those wave lengths (from which we derive the impression of white light). Some such point of view is inherent in
EDITORIALS
557
the criticisms offered by Magitot and ous difficulties. Hue varies with intensity Dubois- Poulsen (Annales d'Oculistique, of illumination. Most investigators have 1937, v. 124, p. 649) under the title abandoned colored lights in favor of "Condemnation of colored test objects." colored papers. Because the exact characIn favor of the taking of. color fields ter of the illumination changed the zone it has been argued that the procedure en- within which the different colors were larges scotomata and renders them more perceived, it was proposed to make the manifest; the diameter of the blind spot tests in full daylight, with the eye preof Mariotte, for example, being increased adapted. It was shown by Alajmo that one fourth with a red as compared with a in these conditions the blue and yellow white test object. It is believed that de- fields coincided and that the red field was fects can be discovered earlier with the 10 degrees larger than the green. There colored objects than with a white object. further remain the problems of obtaining But this apparent advantage of the papers whose colors would be constantly color method is unfortunately neutralized fresh, and winter days as clear as sumby inconveniences, some of which are mer days! Magitot and Dubois-Poulsen characterinstrumental, others attributable to the ize as false the long-cherished belief that patient. The constancy of the results obtained the fields for colors are narrower than depends on the size of the test object, its those for white. "The peripheral achrocontrast with the background, its hue, matopsia of Landolt and Charpentier is an erroneous notion." As a matter of. fact, and the intensity of the illumination. Colored test objects must be relatively the color fields may extend almost as large. Using the gray background recom- far as the field for white. Wentworth mended by Engelking, Ferree, and Rand, obtained this result by using spectral and others, red and green are perceived colors of sufficient intensity; Feree and over a much larger field than on a black Rand, and also Gaudissart, by increasing ground, for the reason that the largest the illumination. With sufficient illuminacolor fields are obtained in the absence tion, green may be perceived as far at the periphery as white. of contrast. The inevitable conclusion is that color It is easy to insure a uniform gray in the perimetric background, but uniformity perimetry as it is usually practiced and and permanence are far more difficult in reported can only be possible with colors regard to colored papers, discs, or balls, lacking purity and brilliancy. To every whose tendency to become dull is in pro- scotoma for color, declare Magitot and portion to the weakness of their color Dubois-Poulsen, there is a corresponding saturation. They must therefore be scotoma for white. Certain minor difficulties pertaining to changed frequently. The attempt to overcome this difficulty by using a luminous the patient are of definite significance but red spot is defeated by the fact that the may be neglected in practice. These inlight intensity of the spot should always clude (1) defects of color and light sense be the same, so that it is necessary to (estimated at 4 percent of the cases) ; (2) resort constantly to new bulbs, adequately the fact that the field for red is smaller standardized, and using an electric cur- in hyperopes and the field for blue dirent of constant strength. minished in myopes, whereas a narrow The two factors in chromatic quality, pupil enlarges the field in both categories namely, tint and luminosity, present seri- of ametropia; and (3) that age has more
558
EDITORIALS
influence in reducing the color fields than the white field. Of much greater importance is the psychic factor. The taking of a visual field taxes the patient's intelligence and power of attention. Evans has shown that fear may enlarge the blind spot. It is often difficult for a person of moderate intelligence to realize that he must at the same time see the test object and the fixation point, and in color perimetry there is added the further demand for correctly recognizing and naming the colored test objects. In short, color perimetry calls for more sustained attention than white. Fatigue may produce islands of amblyopia. Many patients have difficulty in maintaining their attention for longer than 10 minutes. The differences in color perimetry are extreme, and it is impossible to obtain complete standardization. The maximum and minimum figures obtained show wide variation. As contrasted with color perimetry, Magitot and Dubois-Poulsen point out that records of the fields for white have the requisite qualities of simplicity, precision, and constancy of results. This method must, however, be practiced with accurate consideration of all the factors involved. The size of the test object employed should vary according to the zone under examination. Accepting the words in their broad application, the authors quote with approval Moreau's saying that the peripheral field "guesses," the middle field "perceives," and the central field "sees." As a matter of clinical convenience Magitot and Dubois-Poulsen recognize three principal isopters: (I) peripheral, (2) middle, (3) central. With a gray background and constant illumination, and using the customary 33-centimeter are, they apply a 3-millimeter test object
to the zone outside the 3D-degree circle, and a I-millimeter object to the zone between 10 and 30 degrees. The central zone they suggest should be explored with the stereocampimeter, preferably using Evans' technique for angioscotometry. W. H. Crisp
PUBLIC-SCHOOL LIGHTING An interesting and valuable contribution to the science of proper lighting as it pertains to public schools was made by J. Fleischer and A. J. Hoffman in the Transactions of the Illuminating Engineering Society some two years ago. The information gleaned from their investigations should be in the hands of the opththalmological profession to answer the frequent questions. The work was performed in five different public schools in Chicago, involving 78 classrooms and 2,682 students in the fifth, sixth, seventh, and eighth grades. No special conditions were set up beyond the necessary equipment, which consisted of a portable kit so arranged that the lighting intensity on an inclined working plane could be varied from I to 400 foot-candles. The color and quality of the light remained constant, the intensity of illumination being the only variable. In the first trial, undiffused illumination was used, meaning that there was no diffusing medium between the light and the visual task. This was referred to as "undiffused lighting." In the second trial, a screen with good diffusing qualities that eliminated specular reflection was placed between the light and the visual task. The resulting illumination was referred to as "diffused lighting." The child was asked to read good black type on a good quality of white paper, 12-point type being used in the fifth and sixth grades