| OCR Text |
Show J. elin. Neuro-ophthalmol. 4: 129-131,1984. An International Symposium on Color Vision Deficiencies Neuro-ophthalmological Perspectives AVINOAM B. SAFRAN, M.D. ANDRE ROTH, M.D. The International Research Group on Color Vision Deficiencies (lRGCVD) met on the banks of the beautiful Lake of Geneva, Switzerland, from June 23 to 25, 1983, for its 7th International Symposium. Eighteen countries were represented. The scientific program was arranged by Dr. Guy Verriest of Gent, Belgium, and Dr. Andre Roth of Geneva, who hosted the meeting. Sixty papers were presented and numerous valuable contributions were made. Some of these with particular relevance to neuro-ophthalmological practice will be reviewed briefly here. Poor reliability of most currently available pseudoisochromatic plates used for the identification of acquired color vision deficiencies was emphasized. Dr. O. Lagerlof of Stockholm, Sweden, has evaluated 1,000 patients with acquired dyschromatopsia, diagnosed by means of Farnsworth Munsell 100-Hue, Lanthony's 40-Hue, Roth's 28-Hue, and Lanthony's desaturated Panel o test. When these same patients were tested by means of pseudoisochromatic plates, many color vision defects were not detected; 85% showed no sign of color vision deficiency when Ishihara plates were used, and 70% showed no sign when either Farnsworth's tritan or Bostrom-Kugelberg plates were used. Furthermore, it was pointed out by Dr. A. Pinkers of Nijmegen, Holland, that with most color deficiency diagnostic tools (e.g., Farnsworth Munse11100-Hue test, Panel desaturated 0-15, Panel 0-15, New Color Test of Lanthony), a type III acquired blue-yellow defect is reported with aging while no change with age has been detected with pseudoisochromatic tests such as those of American Optical Hardy, Rand and Rittler (AO H-R-R). Dr. Pinkers suggests that the American Optical Hardy, Rand and Rittler test may not be a valid device for screening of acquired color vision defects. Actually, acquired color vision deficiencies are more difficult to evaluate than congenital color vision deficiencies by means of the usual1y avail- From the University Eye Clinic, Geneva, Switzerland. June 1984 able pseudoisochromatic plates, because these plates have been composed of confusion colors and neutral colors of congenital color defects. With the intention of providing a pseudoisochromatic test which would be more sensitive to acquired color vision disorders, Drs. S. H. Tanabe, K. Hukami, and H. Ichikawa of Nagoya, Japan, have devised a new set of plates: the "Standard Pseudoisochromatic Plates, Part 2, for acquired color vision defects." The authors have included in this set nine plates for blue-yel1ow defects. In addition, there are five plates for red-green defects, two plates for scotopic vision, and two demonstrative plates. Of the nine blue-yel1ow plates, seven are also intended to serve for the detection of congenital tritan, and four of the five red-green plates, for the detection of both congenital and acquired red-green defects. Two blueyellow and one red-green plates detect acquired defects only. This new set of plates was made public for the first time at this symposium. No clinical trial has yet been published. However, the authors presented results of color vision screening with this test in 66 cases of central serous retinopathy; 22 showed blue-yel1ow defects. In addition, the authors informed us that they had also tested 52 cases of optic neuropathy secondary to ethambutol intoxication and seven cases of optic nerve disorders of various origin. In these cases of optic nerve disorders, identification of blue-yel1ow color dysfunction with the new plates was reported to be higher than with either American Optical Hardy, Rand and Rittler plates, or Panel 0-15; furthermore, identification of red-green defects was higher than that with American Optical plates. "Standard Pseudoisochromatic Plates, Part 2" will soon be available for about $45.00.* Dr. Pinkers considered various practical aspects of color vision testing, based on his personal clinical experience. He stressed the importance of considering visual field defects when interpreting • For information. write to: Igaku-Shoin. Medical Publisher, 1140 Avenue of the Americas, New York, N.Y. 10036. 129 Color Vision Deficiencies the results of the color vision tests; depending on the extent and location of the scotomas, there may be considerable differences between results of 8° tests, such as American Optical Hardy, Rand and Rittler plates, and those of 2° tests, such as Panel D-15. The authors of this review concur with Dr. Pinkers' opinion. Furthermore, they believe that, in patients with cerebral disorders, results may also vary according to the examination technique because shape recognition is required for certain tests, whereas sequential arrangement of caps is required for others. Dr. Pinkers suggested that test forms of various sizes be used if dubious results are obtained with one examination technique. When screening tests indicate apparent total absence of color discrimination, the patient should be asked to identify large colored surfaces. If the patient really does not recognize colors, red will be described as dark whereas green will be described as light. Interestingly, Dr. Pinkers observed that malingerers often call red "light" and green "dark." The Besan~on anomalometer, conceived by Dr. Roth, is one of the most versatile anomalometers available todayt. It allows every binary color match, as well as the plotting of spectral hue discrimination and saturation discrimination curves. Moreover, it has the unique feature of including an automatic device which provides intermittent covering of the color display for minimizing chromatic adaptation during examination. This is especially helpful when perception of green, blue, or purple is evaluated. With this device, Dr. Roth has evaluated red-green (Rayleigh) and blue-green (Engelking-Trendelenburg or Moreland) matches in seven cases of retrobulbar neuritis and four cases of dominant optic atrophy. All cases showed changes with the Moreland equation, while 11 showed color deficiency with either the Engelking-Trendelenburg, or the Rayleigh equation. Dr. Roth first emphasized that: 1) in acquired defects, the blue-green matches are modified earliest and most seriously, the red-green match being also modified, but to a lesser degree; and 2) in combinations of congenital and acquired defects, the Moreland bluegreen matches are always modified. Therefore, differentiation of congenital from acquired or mixed forms is facilitated by the use of blue-green matches. Dr. Roth then established that matches made with the Moreland equation consistently gave results that were quantitatively more abnormal than those obtained when the EngelkingTrendelenburg equation was used. He concluded that the combined use of Rayleigh and Moreland equations provide at least as many diagnostic t The instrument is manufactured by Statice, rue Lavoisier, ZI. des Tilleroyes, F-25000 Besan~on, France. 130 clues as the classical plate and arrangement tests (e.g., Ishihara plates and Farnsworth Munsell 100-Hue), and can be considered relevant for routine examination of acquired optic nerve disorders. When the distance between two wavelengths of the visible spectrum exceeds a certain value, the sensation produced by their mixture is that of a color that is not present in the solar spectrum. Such colors are called extraspectral colors, or purples. In clinical practice, these colors have received less attention than spectral ones. Yet, purples are strongly represented in the 4th cortical visual area (S. Zeki: The representation of colors in the cerebral cortex. Nature 284: 412-418,1980). In their paper (presented at the symposium), Dr. Roth and Ms. D. Hermes reported that, with the Besan~on anomalometer, they studied five eyes with retrobulbar optic neuritis, for metameric matches of the purples. The subjects were also evaluated with Ishihara plates, Farnsworth Munsell 100-Hue, and 28-Hue, both saturated and desaturated. The authors showed that the matching range of purples is widened in medium degree acquired defects, but not in mild defects. Therefore, for retrobulbar optic neuritis, purple equations are not as sensitive as the Moreland equation. This apparently is the first time that the function of diseased optic nerves has been evaluated by means of purple equations. A new pocket device approaching the properties of an anomaloscope was presented by Drs. F. Bolle, H. Krastel, and W. Jaeger, of Heidelberg, Federal Republic of Germany. It is based on LED technology and allows for the evaluation of a redgreen equation. In cases of acquired disorders of the optic nerve, the authors have observed a broadening of a Rayleigh-like equation. The instrument is now undergoing a process of spectral sharpening by means of additional filters, and probably will be commercially available within a few months. The McCullough effect is a contingent visual aftereffect, induced by looking at a horizontal red-black grating every few seconds, for a period of several minutes. Subsequently, a vertical white-black grating appears reddish, and a horizontal white-black grating appears greenish. This phenomenon differs from the usual afterimage in that it is not restricted to the size of the previously shown pattern. Furthermore, it may persist for days or weeks. Inspired by the design of C.C.D. Shute (Shute, C.C.D.: Subjective colors and brain functions. Elldeav. New Ser. 5: 141-146, 1981), Drs. ]. L. Vola, P. Gastaud, and J. Leid, of Marseille, France, devised a new instrument for quantifying the McCullough effect. It is of potential interest for neuro-ophthalmological evaluation, since brain mechanisms have been suggested to Journal of Clinical Neuro-ophthalmology explain various characteristics of the McCullough effect, such as its interocular transfer. The authors and Dr. W.K Felgenhauer, of Geneva, Switzerland, reported the case of a patient who presented with episodes of transient cerebral achromatopsia. Apparently, alteration in color vision had occurred either in isolation or following a temporary loss of vision. It was identified as a result of careful history taking. It has rarely been described in the literature as a transient isolated phenomenon. As in the case of other fleeting visual defects induced by vertebrobasilary insufficiency, patients presenting with this disorder may not be aware of any specific change in their visual function, although they may notice some alteration of vision. Many other papers were presented which were of interest for neuro-ophthalmologists. Dr. F.M. de Monasterio of Bethesda, Maryland, critically reviewed electrophysiological investigations of color vision at the cellular level, emphasizing that many color-opponent cells in the retina and the lateral geniculate body can be misclassified as nonopponent cells if they are studied without chromatic adaptation. Dr. E. Zrenner, of BadNauheim, Federal Republic of Germany, re- June 1984 Safran, Roth viewed extensively the topics of ERG, VEP, and color vision. Fundamental aspects of metameric matches relevant for assessment of color vision were considered thoroughly by Dr. J. Pokorny, of Chicago, Illinois. Excellent papers dealing with clinical electrophysiology and colored stimuli were given by Dr. M.L.F. de Mattiello and associates (Buenos-Aires, Argentina), Dr. Y. Grall and associates (Paris, France), and Drs. Y. Vji and M. Yokoyama (Mie, Japan). Practical aspects of quantification of color vision deficiencies by means of Farnsworth Munsell 100 Hue and Panel 0-15 were reexamined by Dr. J. Bowman and associates (Brisbane, Australia), Dr. Block and associates (Glasgow, Scotland), and Dr. K. Kitahara (Tokyo, Japan). These, as well as other valuable papers, are to be included in the Proceedings of the Symposium, which will be printed by Dr. W. Junk, Publishers, The Hague, Holland. The next Symposium of the International Group on Color Vision Deficiencies will be held in southern France, in June 1985. Write for reprints to: Avinoam B. Safran, M.D., Clinique d'Ophtalmologie, H6pital Cantonal Universitaire, CH-1205, Geneva, Switzerland. 131 |
