JOURNAL OF THE OPTICAL SOCIETY OF AMERICA Unilateral Color Deficiency, Congenital and Acquired JENNIFER COX Technical Optics Section, Imperial College, London, S. W.7., England (Received October 11, 1960) The literature on unilateral color vision defects is reviewed, with particular reference to a unilateral deuteranope recently described by Graham and his associates and by Walls. A similar atypical unilateral deuteranomalous subject is described where the color vision defect has been acquired due to the disease retrobulbar neuritis. The hue discrimination and luminosity curves for this patient are compared with those found by Graham, and the possibility that retrobulbar neuritis could be responsible for a unilateral deutan defect with good visual acuity is discussed. IN recent years the interest in unilateral color vision defects has been revived and details of one such person have been widely published.'-" Although details of people with defective color vision in one eye only have appeared as long ago as 1879, and approximately 40 have been recorded by reliable sources, it is not usually the practice to screen the color vision of each eye separately. Thus, we may assume that dissimi- larities between the two eyes have been largely over- looked and it is more difficult to assess the genetic significance or incidence of this type of color defect. Individuals with one normal eye and one color-defective eye provide direct evidence of the color perceptions of the color-blind, since they are able to compare the appearance of the same stimuli presented to each eye in turn. This is in contrast to the situation with the regular bilateral defects where one may have only theories upon which to base an assertion in regard to what hues are actually seen in the spectrum. When trying to choose between rival theories of normal color vision, the potential theoretical value of a unilateral defect is therefore great. It is even more valuable when a genetic basis can be proved or, in the case of an acquired defect closely simulating a hereditary one, if the site of the lesion can be isolated. No one investigator has seen enough unilateral cases of all sorts to have resolved the questions which they raise. In the present paper only one case of acquired unilateral deficiency, of possible great importance, will be set forth in detail. It will be compared with that one case of apparently congenital origin which it seems most closely to resemble. What this comparison may be worth is for some future investigator to say after these strands have been drawn together with many others. 1 C. H. Graham, Y. Hsia, and E. Berger, J. Opt. Soc. Am. 45, 407 (1955). 2 C. H. Graham and Y. Hsia, Science 120, 780 (1954). 3 C. H. Graham and Y. Hsia, Science 127, 675 (1958). 4 C. H. Graham and Y. Hsia, Proc. Natl. Acad. Sci. U. S. 44, 46 (1958). ' C. H. Graham and Y. Hsia, Proc. Nati. Acad. Sci. U. S. 45, 96 (1959). 1C. H. Graham and Y. Hsia, Proc. Am. Phil. Soc. 102, 168 (1958). 7 E. Berger, C. H. Graham, and Y. Hsia, J. Opt. Soc. Am. 48, 614 (1958). 8 E. Berger, C. H. Graham, and Y. Hsia, J. Opt. Soc. Am. 48, 622 (1958). 9 G. L. Walls, Am. J. Optom. 35, 449 (1958). 10 G. L. Walls, Am. J. Optom. 36, 169 (1959). The accepted theories of the genetic transmission of color-vision deficiency do not allow that a unilateral defect may occur as a straightforward entity. A sex- linked color anomaly is usually manifest as a regular well-defined binocular defect in man, with charac- teristics which vary only within narrow limits. The anomaly is carried on the nonhomologous portion of the x chromosome and any aberration likely to cause a unilateral color defect (such as fracture of the chromo- some in some cells) is likely to produce other genetic peculiarities as well. The incidence of congenital color- vision defects in males is usually quoted as 8%. In actual fact, even with large samples of over a thousand people or more, this figure is found to vary widely from place to place and in different races." Individual samples in Europe and America, with a minimum of a thousand subjects, only place the incidence of color defects between 6 and 10% (Table I). The figure is signifi- cantly lower in the Asian and Negroid races. On the whole, fewer women defectives are found in the equiva- lent surveys than would be expected if a simple sex linkage is assumed (Table II). For a woman to be defective she must receive two defective genes, one from each parent, and, therefore, the incidence should correspond to the square of that found for men. The lower figure obtained is explained by some theoreticians as due to a "cancelation" resulting in normal vision when a women possesses two genes for different types of color defect (e.g., protanopia and deuteranopia). Occasionally cases are reported in the literature which appear to contradict the theory of sex linkage and which suggest that a more complex transmission may be the case. It also seems possible that factors other than genetic ones play a part. Recent advances in the technique of nuclear sexing and chromosome counting seem to hold the clue to the genetic puzzle, but again genetic aberrations may not account for all the observable differences." This present paper emphasizes the fact that unilateral color defects can be acquired long after birth, due to the effect of eye disease, even when visual acuity is normal. One of the first references to a unilateral color defect was made by Holmgren as early as 1881.12 He obtained 11 R. Kherumian and R. W. Pickford, Hereditg et Frequence des Dyschroinatopsies (Vigot Frres, Paris, 1959). 12 F. Holmgren, Proc. Roy. Soc. (London) 31, 302 (1881). 992 VOLUME 51, NUMBER 9 SEPTEMBER, 1961
Transcript
JOURNAL OF THE OPTICAL SOCIETY OF AMERICA
Unilateral Color Deficiency, Congenital and Acquired
JENNIFER COXTechnical Optics Section, Imperial College, London, S. W.7., England
(Received October 11, 1960)
The literature on unilateral color vision defects is reviewed, with particular reference to a unilateraldeuteranope recently described by Graham and his associates and by Walls. A similar atypical unilateraldeuteranomalous subject is described where the color vision defect has been acquired due to the diseaseretrobulbar neuritis. The hue discrimination and luminosity curves for this patient are compared with thosefound by Graham, and the possibility that retrobulbar neuritis could be responsible for a unilateral deutandefect with good visual acuity is discussed.
IN recent years the interest in unilateral color visiondefects has been revived and details of one such
person have been widely published.'-" Although detailsof people with defective color vision in one eye onlyhave appeared as long ago as 1879, and approximately40 have been recorded by reliable sources, it is notusually the practice to screen the color vision of eacheye separately. Thus, we may assume that dissimi-larities between the two eyes have been largely over-looked and it is more difficult to assess the geneticsignificance or incidence of this type of color defect.Individuals with one normal eye and one color-defectiveeye provide direct evidence of the color perceptions ofthe color-blind, since they are able to compare theappearance of the same stimuli presented to each eyein turn. This is in contrast to the situation with theregular bilateral defects where one may have onlytheories upon which to base an assertion in regard towhat hues are actually seen in the spectrum. Whentrying to choose between rival theories of normal colorvision, the potential theoretical value of a unilateraldefect is therefore great. It is even more valuable whena genetic basis can be proved or, in the case of anacquired defect closely simulating a hereditary one,if the site of the lesion can be isolated.
No one investigator has seen enough unilateral casesof all sorts to have resolved the questions which theyraise. In the present paper only one case of acquiredunilateral deficiency, of possible great importance, willbe set forth in detail. It will be compared with that onecase of apparently congenital origin which it seems mostclosely to resemble. What this comparison may beworth is for some future investigator to say after thesestrands have been drawn together with many others.
1 C. H. Graham, Y. Hsia, and E. Berger, J. Opt. Soc. Am. 45,407 (1955).
2 C. H. Graham and Y. Hsia, Science 120, 780 (1954).3 C. H. Graham and Y. Hsia, Science 127, 675 (1958).4 C. H. Graham and Y. Hsia, Proc. Natl. Acad. Sci. U. S. 44,
46 (1958).' C. H. Graham and Y. Hsia, Proc. Nati. Acad. Sci. U. S. 45,
96 (1959).1 C. H. Graham and Y. Hsia, Proc. Am. Phil. Soc. 102, 168
(1958).7 E. Berger, C. H. Graham, and Y. Hsia, J. Opt. Soc. Am. 48,
614 (1958).8 E. Berger, C. H. Graham, and Y. Hsia, J. Opt. Soc. Am. 48,
622 (1958).9 G. L. Walls, Am. J. Optom. 35, 449 (1958).10 G. L. Walls, Am. J. Optom. 36, 169 (1959).
The accepted theories of the genetic transmission ofcolor-vision deficiency do not allow that a unilateraldefect may occur as a straightforward entity. A sex-linked color anomaly is usually manifest as a regularwell-defined binocular defect in man, with charac-teristics which vary only within narrow limits. Theanomaly is carried on the nonhomologous portion of thex chromosome and any aberration likely to cause aunilateral color defect (such as fracture of the chromo-some in some cells) is likely to produce other geneticpeculiarities as well. The incidence of congenital color-vision defects in males is usually quoted as 8%. Inactual fact, even with large samples of over a thousandpeople or more, this figure is found to vary widely fromplace to place and in different races." Individual samplesin Europe and America, with a minimum of a thousandsubjects, only place the incidence of color defectsbetween 6 and 10% (Table I). The figure is signifi-cantly lower in the Asian and Negroid races. On thewhole, fewer women defectives are found in the equiva-lent surveys than would be expected if a simple sexlinkage is assumed (Table II). For a woman to bedefective she must receive two defective genes, onefrom each parent, and, therefore, the incidence shouldcorrespond to the square of that found for men. Thelower figure obtained is explained by some theoreticiansas due to a "cancelation" resulting in normal visionwhen a women possesses two genes for different typesof color defect (e.g., protanopia and deuteranopia).
Occasionally cases are reported in the literature whichappear to contradict the theory of sex linkage andwhich suggest that a more complex transmission maybe the case. It also seems possible that factors otherthan genetic ones play a part. Recent advances in thetechnique of nuclear sexing and chromosome countingseem to hold the clue to the genetic puzzle, but againgenetic aberrations may not account for all theobservable differences." This present paper emphasizesthe fact that unilateral color defects can be acquiredlong after birth, due to the effect of eye disease, evenwhen visual acuity is normal.
One of the first references to a unilateral color defectwas made by Holmgren as early as 1881.12 He obtained
11 R. Kherumian and R. W. Pickford, Hereditg et Frequence desDyschroinatopsies (Vigot Frres, Paris, 1959).
12 F. Holmgren, Proc. Roy. Soc. (London) 31, 302 (1881).
992
VOLUME 51, NUMBER 9 SEPTEMBER, 1961
UNILATERAL COLOR DEFICIENCY
TABLE I. Incidence of color deficiency in males.
PercentNumber Number of
Country Examiners Date tested defective defectives
two unilateral partially color-blind people, the first forviolet and the second for red. In both cases the othereye has a "weak" color sense but was otherwise normal.Cases known any earlier were mostly of "tritanopia"accompanying retinal detachment. In 1931 Miles andBeaumont3 estimated the incidence of unilateral defectsas 4% of all defectives. Judd' 4 described 37 unilateraldefectives found in the literature up to 1948 but con-cludes that only eight of these were tested quantita-tively. In the same year Sloan and Wollach15 describea unilateral deuteranope with the other eye slightlydeuteranomalous.
Of the 37 people described by Judd, the cause of thedefect is listed in 19 cases as inherited, and in 10 casesas acquired (Table III). The etiology of the remainderwas uncertain. The type of the defect observed wasreclassified by Judd and, although these still may be alittle uncertain due to diverse methods of measurement,it is encouraging to note that three cases of opticatrophy produce clear deutan defects, and a patientwith retinitis acquired tritanopia. These agree well withcurrent surveys of acquired defects."-"'
The most important and interesting subject men-tioned in the literature, however, is the one recentlydescribed by Graham and his associatesl-8 and byWalls.9"l0 This is that of a young woman A.H.C. witha normal right eye and color-defective left. She is amyope, -2D right and -4D left with which correctionher acuity is "normal."
Graham et al. have repeatedly characterized A.H.C.'sleft eye as essentially, although not quite typically,deuteranopic. In particular, Graham has considered her
1' W. R. Miles and H. Beaumont, Am. J. Ophthalmol. 14, 636(1931).
14 D. B. Judd, J. Research Natl. Bur. Standards 41, 247 (1948)."L. L. Sloan and L. Wollach, J. Opt. Soc. Am. 38, 502 (1948).16 G. L. Walls, Am. J. Ophthalmol. 39 (No. 2, Part II), 8 (1955).17 J. Frangois and G. Verriest, Ann. oculist. (Paris) 190 (1957).8 J. Cox, Brit. J. Physiol. Opt. 17, 195 (1960).
greatly depressed luminosity curve (Fig. 1) to berepresentative of regular bilateral deuteranopia. Wallsvigorously disagrees,'9 and calls attention to the workof Heath,2 0'2' which shows that in true deuteranopiathe absolute photopic luminosity curve is elevated(above the color-normal's) except in the blue-violetregion.
Walls has found that the luminosity discrepanciesbetween A.H.C.'s two eyes, plotted by themselves,yield a curve which is acceptable as that of the green-ness receptor of three-component theory. He suggeststhat in A.H.C. no receptor type is lacking, but that thegreenness receptor is inhibiting brightness instead ofcontributing to it. The chromatic activities of thegreenness and redness receptors being neurally coupled,A.H.C. has a blue-and-yellow subjective spectrum anda deuteranopic neutral point. These are, however, theonly characteristics in which she resembles a deuter-anope. Walls emphasizes that A.H.C.'s "hue discrimi-nation curve" (Fig. 2) is not in the least like the simpleparabola, centered upon the neutral-point wavelength,which one expects in a deuteranope. In particular the
log. rel.sensitivity0
40 /, - , -
[ /I -norm--- color-201
ial eyer-blind eye
480 S20 60 6? 4 0wave ength mp.
FIG. 1. The luminosity curve of A.H.C's defective eye is de-pressed compared to that of the normal eye, especially in theshorter wavelengths (from Graham and Hsia).
1 G. L. Walls, A.M.A. Arch. Ophthalmol. 62, 13 (1959).20 G. G. Heath, Science 128, 775 (1958).21 G. G. Heath, Science 131, 417 (1960).
993September 1961
JENNIFER COX
TABLE II. Incidence of color deficiency in females.
PercentNumber Number of
Country Examiners Date tested defective defectives
discrimination of hues in the extreme blue region of thespectrum is much better than in classical deuteranopia.The short-wave portion of this curve emulates trit-anopia rather than deuteranopia. The unilateraldeuteranope described in 1948 by Sloan and Wollach' 5
was much more like ordinary deuteranopes.Since the case of an acquired unilateral deutan
defect described below (H.H.) resembles A.H.C. morethan any other known person, an important questionarises: how certain is it that A.H.C.'s defect was nlotacquired postnatally? The pertinent information onthis matter has not been published, but comes throughG. L. Walls as a personal communication:
"In the first place, A.H.C. never knew of the differ-ence between her two eyes until she was 25 years old.This may seem to imply that the defect of her left eyecould not have been congenital. Actually, however,just such an experience occurs frequently with geneticdefects. Asymmetry is discovered purely by accident,for example, with the first use of a monocular micro-scope in a college laboratory course. One of the puzzlingthings about congenital unilateral color blindness isthe curious fact that when the subject is seeing bin-ocularly, all colors are seen as if both eyes are normal.If he or she never happens to look at the same colorstimuli with first one eye and then the other, theasymmetry will go unrealized.
"In all that Graham et al. have published on A.H.C.,there is mention of possible color deficiency in a bloodrelative only in a footnote in one paper, by Berger,Graham, and Hsia.7 Here it is stated that her fatherperformed normally with each eye on three differentpseudoisochromatic chart tests, and with the right eyeon the Hecht-Shlaer (filter) anomaloscope. His left eye'required a somewhat greater than average amount of
red to match a yellow. The settings, nevertheless,probably lie nearer the distribution for normal thanfor protanomalous eyes.'
"Soon after her own deficiency came to light, A.H.C.herself gave chart tests to various relatives. Hermother's only living brother made errors such thatA.H.C. tentatively determined him to be deuteranoidbut not deuteranopic. The Columbia group neverfollowed up this lead."
Walls was able to examine both A.H.C.'s father(B.B.H.) and her maternal uncle (A.N.S.) in July, 1959and used the AO H-R-R test and the Nagel anomalo-scope.
"B.B.H. made no errors on the AO H-R-R, usingboth eyes; but with his left eye at the Nagel he wasdefinitely a protanomal, with a redward deviation of12 scale units from the mean normal red + greensetting, and a matching range of 12 units. He exhibitedno contrast effects; and while he used a somewhatlow intensity of yellow in his perfect matches, heclaimed that red traffic lights appeared just as brightto him as green ones. Walls considers that he may beone of those not uncommon protanomals whoseluminosity curve is nearly normal. He was a railroadfireman for eight years, qualifying as an engine-driver,and in that period repeatedly passed yarn and lanterntests. But when his left eye (unfortunately the only onetested) is isolated, he is clearly defective. At one pointin the examination, he described the anomaloscopefield as being gray above and purple below!
"A.N.S. made no errors on the AO H-R-R beyondthe screening plates, thus receiving the label 'mildred-green defect, unclassified as to type.' At the Nagel,however, he showed a nine-unit redward deviation withan eight-unit matching range. He also obtained the
TABLE III. Recorded cases of acquired color vision defects.
contrast effects characteristic of a protanomal, seeingthe lower-half of the field as a reddish yellow whenmatched in brightness to the pure green above (whichhe called bluish-green), but seeing the lower-half asyellow when it was a brightness match for the pure redabove. No means were available with which to make anysort of evaluation of his long-wavelength luminosity."
With a color-normal mother and brother, A.H.C.cannot have received more than one gene for deuter-anopia or deuteranomaly, if her mother happens tocarry either. Inevitably, she has her father's gene forprotanomaly. With a protanomalous brother, hermother is much more likely to have had a protanomalygene to give to A.H.C. than any deuteranoid gene. Shecould not be a compound carrier and have a normalson. But if A.H.C. has two genes for protanomaly sheshould be a bilateral protanomal, and if she has onlyone she should be normal. In a female, a unilateralembryonic somatic mutation of a normality gene intoa deuteranoid one should not produce a color-blind eye.However, if an inherited protanomaly gene was presentin the same cells with the deuteranoid mutant gene,then any result is believable. For, we have alwaysbefore us the example of Weale's J.G., a compoundhleterozygote for protanomaly and deuteranomaly whowould be expected to be normal but instead is totallycolor blind.' 6
While A.H.C. cannot be proved to have an inheritedbasis for any sort of deuteranopia-like defect, it iscertain that she has at least one inherited color-defectgene, may have two, or may have a somatic-mutantgene. The evidence that her defect has a genetic basisis thus much stronger than is any reason to assume thatit must have been acquired.
LOR DEFICIENCY
AAW,40-
0C Deuteranope'30t
.0 W
W -\
0 -'20
,,,, ,/IC <OaCt
400 40 80 520 60
995
"I, \, I
., I
\--'A.H.C.
. . . . . . .
600 40 80 mpwavelength A
FIG. 2. The curve found by Pitt for a typical deuteranope issuperimposed on the hue discrimination curve determined byGraham and Hsia for A.H.C. The loss of discrimination illustratedby A.H.C. is not typical of a deutan defect. In particular, thediscrimination in the blue region of the spectrum between 480and 400mu is similar to that found in tritanopia.
The disease retrobulbar neuritis is an inflammationof the optic nerve in the region behind the eye. Theinflammation is, therefore, not visible with the oph-thalmoscope except in the later stages when the diskmay be whiter due to secondary atrophy. The attackoccurs suddenly with rapid loss of vision. The patientgoes blind almost overnight. Characteristically the eyerecovers spontaneously without treatment and acuitygradually improves. The vision may be fully restoredor may remain slightly impaired; in subsequent attacksthe acuity is less likely to return to 6/6. Retrobulbarneuritis is usually due to demyelinating disease and aunilateral inflammation occurring in the late twentiesis often the first symptom of multiple sclerosis.
During a recent analysis of color-vision defectsacquired in diseases of the eye,'8'2 2 four cases of uni-lateral retrobulbar neuritis and one binocular retro-
6/3/58 6/18+ x x x x x x x x x x x x x x x A r r r r Slight B-YStrong deutan
6/17/58 6/12 x x x x r x x x x x x A A o A r r r r Slight B-YStrong deutan
6/24/58 6/12 x x x x r r x x ,x x x x x x o A r r r r Strong deutan7/2/58 6/12+ x x x x r r - - x x o o A + r r r r r r Mild deutan7/8/58 6/9- x x x x r r - x x o x r x + r r r r r r Ambiguous R-G7/15/58 6/9 x x x x r r x x x x o o r + r r r r r r Mild deutan8/27/58 6/9 x x x x r r x x x x o x x + o A r r r r Mild deutan3/10/60 6/9 x x x x r r x x x x o o A + o A r r r r Mild deutan
6/3/58 6/18+ r r r r r xxx xx x x x x x x x r r r r x x x x R-Gdefect6/17/58 6/12 r x r x x x r x x x x x x x x x x r r r r 2- 4- 3- 9- Deutan6/24/58 6/12 r c r x x r c x x x x x x x x x x c c c c 2- 4- 3- 9- Deutan7/2/58 6/12+ r c c r r c c c c x x x x x x x x c c c c 2- 4- 3- 9- Deutan7/8/58 6/9- r r r r r c c c c x x x x x x x x c c c c 2- 4- 3- 9- Deutan7/15/58 6/9 r c r r r c c c c x x x x x x x x c c c c 2- 4- 3- 9- Deutan8/27/58 6/9 r r r r x c c c c x x x x x x x x c c c c 2- 4- 3- 9- Deutan3/10/60 6/9 r c c r r c c c c x x x x x x x x r r c c 2- 4- 3- 9- Deutan
r =plate read correctly; x =number or motive not visible; "-=motive visible but not distinguishable; c =confusion number seen; A-0 Plates(H-R--R); o =circle only distinguished; + =cross only distinguished; A =triangle only distinguished.
"'J. Cox, Brit. J. Physiol. Opt. 18, 3 (1961).
II
JENNIFER COX
575
570
(a) 6/3/58 (c) 6/24/58
(b) 6/17, 58 (d) 7/2/58FIG. 3. The plots for the 100-hue test showv the recovery of monocular retrobulbar neuritis and the consequent changes in color dis-
crimination for H.H. The radial lines represent the 85 hues of the test and the distance from the central circle indicates the error score.As the patient recovers, the error score becomes less and the confusion bands shrink. Twvo confusion areas lying on a diagonal acrossthe diagram indicate a deutan defect. [Parts (e)-(h) on opposite page.]
bulbar neuritis were examined. One patient with aunilateral inflammation (H.H.) was examined ex-tensively at intervals during the period of recovery.The tests used were the Ishihara plates (10th Ed.),the American Optical Company plates (Hardy, Rand,and Rittler), and the Farnsworth-Munsell 100-hue test.The luminosity curve and hue discrimination curvewere determined with the Wright colorimeter and thediagnosis, initially of deuteranopia and later of deuter-anomaly, was confirmed with the Nagel anomaloscope.The patient's unaffected left eye had normal trichro-matic vision with an acuity uncorrected of 6/5. Theresults for the defective right eye are given in Table IV
for each plate in both series together with the date,visual acuity, and diagnosis.
It will be noted that at the beginning of the study inJune, 1958 the acuity was 6/18 and improved in sixweeks to 6/9 but did not improve further. At the firsttest the color-vision defect was an unspecified red-greenanomaly, which as the acuity improved resolved intodeuteranopia and subsequently into deuteranomaly.There were small discrepancies and ambiguities betweenthe two tests, but on the whole the defect was diagnosedas characteristic of a congenital deutan defect. Theresults are consistent with a recent survey of thereliability of pseudoisochromatic plates.22 The patient
996 Vol. 51
September 1961
580
575570
UN I LATERAL
(--) 78/58
COLOR DEFICIENCY
FIG. 3 (continued).
FIG. 4. Luminosity and hue discrimination curves for H.H.showing an acquired monocular deutan defect caused by retro-bulbar neuritis. The luminosity curve for the defective eye isnarrower than the curve for the normal eye and is particularlyreduced in the shorter wavelengths. The hue discrimination curveis similar to that of a deuteranomolous trichromat found byWright but differs in the suggestion of improved discriminationbelow 460mLu.
log. rel.sensitivity1-0
0*5
0 - -normal ey--- color-blind
-05 480 520 60 600 40. wavelength mp
W,U
W I
._
o oc C
tn z.2 >
._a
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3
2
eye
0
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!0
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c 460 500 40 80wvength A M
997
(g) 8/27/58
(f) 7/15/58
500 495 490
(h) 3/10,/60
A
I
998 ~~~JENNIFER COXVol. 51
TABLE V.
(a) R.F. retrobulbar neuritis R.E. Age 27
A.O. Plates (H-R-R)Date V/A 1 2 34 5 6 7 89 1011 1213 1415 16 l17l89 20 iag. ofdefect3/20/58 6/36 x x x x"- "" x x x x "-" x x x "~ r r r r r Slight B-Y
Strong R-G5/15/58 6/24 x x rx r r r rr x r o r + r r r r r r Mild deutan7/3/58 6 / 9 - x xrx r r r rr + r r r r r r r r r r Slight deutan
3/20/58 6/36 r c r r x x x x x x x x x x r r r r x x x x R-G defect5/15/58 6/24 r r r r x r r x x x r x x r r x r r r r r x x r x R-G defect3/7/58 6/9- r r r r r r r c c r r r x r r r r r r c c r r 3- 9- Deutan
4/30/59 6/6 r r r X X X r x X r r X x x r X X r r r r x x24 25
(d) N.D. retrobulbar neuritis O.U. Age 31
Right eyeA.O. Plates (H-R-R)Date V/A 1 2 34 56 7910 111 21415 16 17 819 20 Diag. of defect
3/27/58 6/24 X x x r r x xx x x "- x -"-- x x r r r r R-G dfect7/10/58 6/24 Xx x x x x x xx x X x A o nr r r r Slight B-YStrong R-G5/26/59 6/24 X x xxx Ax x Xx x x x + o A r r r r Slight B-Y____________________________________________________________Deutan
3/27/58 6/5 x x x rr r rr r X r r r r r r r r r R-G defect7/10/58 6/6 x xr - r A rr r r r r r r r r r r r Slight deutan5/26/59 6/6 xX xr x r r x r r r o r A r r r r r r r Deutan
3/27/58 6/Sr r r r r x r r r r r r r r x X r r r r r X -5 -6 Protan7/10/58 6/6 r r r r r X r r c x x x x X X r x r r r r r -2 -5 -6 Protan
998
September 1961 UNILATERAL COLOR DEFICIENCY
570
Soo us490
(a) 3/20,'58 (b) 5/15/58
FIG. 5. These plots for the 100-hue test show the recovery of monocular retrobulbar neuritis and theconsequent changes in color discrimination for R.F.
had suffered a slight relapse when examined in August,1958. When examined in March, 1960 the acuity hadstill not improved beyond 6/9 and the color defect wasclearly deuteranomalous. Ophthalmoscopically therewas very little difference between the two eyes but theright optic disk was slightly whiter.
The plots for the 100-hue test likewise indicateddeuteranopia after an initial ambiguity (Fig. 3). Asthe patient recovered, the color confusion became lessmarked and within narrower limits. In particular, theconfusions in the yellow region of the spectrum seemed
to indicate the severity of the anomaly. Errors in thisregion increased when the patient suffered a relapse.
The wavelength discrimination and luminosity curvesfor both eyes were measured on three separate occasions.
Those for the left eye were completely normal. Thehue-discrimination curve for the right eye indicatedan atypical red-green defect (Fig. 4) and the luminositycurve is suggestive of a deutan defect. Both of thesecurves more closely resemble those of A.H.C. than thoseof regular deuteranopes.
Examination of the other patients with this diseaseon the whole confirms the results obtained for H.H.,although the color loss is less precise (Table V). R.F.
examined on three occasions showed a classical deutan
defect which was considerably reduced when the acuityhad improved to 6/9. The 100-hue test also shows thereduction of the defect (Fig. 5).
The three other patients examined gave ratherdisappointing results, possibly because acuity was poor
or because the attack was not the first. C.P. had anacuity of only 6/60 and the red-green defect wasunspecified. Although J.F. had an acuity of 6/6, thiswas her third attack of retrobulbar neuritis, and againthe red-green defect was unspecified.
The patient with binocular retrobulbar neuritis dueto disseminated sclerosis had an active inflammationin both eyes and also suffered temporary muscle
paralysis; the visual acuity did not improve during theperiod of examination. The results of the color-visiontests were ambiguous, but the red-green defect wascertainly severe. It is interesting to note that when thecolor defect is severe a small amount of tritanopia,indicated by the plates, also may be present. Wallsobserved this same sort of thing in A.H.C.
These results show that in a unilateral color vision
defect due to retrobulbar neuritis, the visual efficiencymay be nearly normal, and while the defect is notidentical with regular deuteranopia it is not unlike aknown atypical deutan defect (that of A.H.C.) whichin all probability has its basis in some combination of
red-green defect-genes and unusual actions thereof.
ACKNOWLEDGMENTS
I would like to thank Professor W. D. Wright forhis help and encouragement, and Professor A. Sorsbyfor permission to examine patients at the Royal EyeHospital, London. I am particularly grateful to Dr.G. L. Walls for information on the heredity of A.H.C.
