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Visual thresholds in the deutan type of red-green deficient colour vision.

Defective temporal integration for a foveally fixated 100' of arc red (660 nm) Btest flash presented on a 30 cd/m2 yellow ( Schott , OG 530) background was measured in subjects with deuteranopia , as well as in subjects with anomalous trichromacy of the deutan type. The mean integration time was 77 +/- 17 ms in 12 normal subjects but only 35 +/- 6, 46 +/- 11 Band 41 +/- 15 ms in respectively 6 subjects with deuteranopia , 7 with extreme deuteranomaly Band 9 with deuteranomaly . An increase in the test duration from 10 to 200 ms increased the mean relative sensitivity by 0.85 +/- 13 log units in the normal subjects compared with 0.45 +/- 0.05, 0.57 +/- 12 and 0.56 +/- 19 in subjects with deuteranopia , extreme deuteranomaly and deuteranomaly .

Adolescent

The new color test.

The New Color Test allows estimation of the neutral zone (separation phase) and the characteristic color confusions (classification phase) using Munsell colors. The width of the neutral zone is estimated by the ranges of hues confused with grey. The severity of chromatic discrimination loss for a given axis is estimated by the range of chromas confused with grey.

Color Perception Tests

Examination of colour vision by use of induced contrast colours. Design of a new series of tissue paper contrast tests.

The ability to induce contrast colours is evident in normal persons by the tissue paper contrast principle. However, tests of good quality are not easily available. The design of a new series of charts follows two principles: 1) Selection of background hues in accordance with the maximally desaturated regions of the spectrum as seen by the colour defectives. 2) Exact adjustment of the neutral test field (constituted by the chart figures) in order to eliminate any false clue due to brightness contrasts. By introducing chart figures of alternative grey values appropriate tests can be attained for each type of colour vision defect. 37 persons with congenital colour defect and 15 persons with acquired defects were examined. The charts, according to the criteria for selection, proved to be selective in their screening efficiency.

Adolescent

Tokyo Medical College Test in acquired dyschromatopsia.

In order to find a successor for the Hardy, Rand and Rittler (AOH-R-R) test the author made a comparison between the AOH-R-R and the Tokyo Medical College (TMC) tests in acquired dyschromatopsia. The diagnosis of the TMC type of a red-green defect is often in contradiction with the results of other color vision tests. In grading the severity of a red-green defect the TMC classification is shifted with regard to the AOH-R-R classification. A corrected grading in better agreement with the AOH-R-R classification is proposed. The TMC blue-yellow screening plates are more sensitive than the AOH-R-R blue-yellow screening plates. A TMC (supermild) blue-yellow defect in general corresponds to blue-yellow defects detected by FM 100 Hue and its derivatives. In the study of acquired dyschromatopsia, it is necessary to use a test battery. In our opinion the TMC can be used in such a test battery although it is not a real successor to the AOH-R-R. If ever the AOH-R-R is reprinted, the blue-yellow plates should be extended to a 'supermild' degree as are the TMC blue-yellow plates.

Adult

[Screening of early color vision loss in diabetic patients].

Colour vision defects have been claimed to appear in diabetes before any retinopathy is visible. In the present study diabetic patients and non diabetic control subjects were screened with two different colour vision tests which include both red-green and blue-yellow parts, and are suitable for quantitative analysis of scores. The Lanthony 40 Hue test and the Tokyo Medical College--T.M.C. tables were used to assess colour vision in 106 diabetic (50 insulin dependent and 56 non insulin dependent) patients and in 99 non diabetic control subjects. Diabetic patients without visible retinopathy, familiar colour vision defects and/or lens changes, had significantly higher scores than control subjects in both eyes. The differences were more evident in non insulin dependent patients. Statistical analysis showed that early loss of colour vision was correlated with age and duration of diabetes for older patients, while correlation with glycosylated hemoglobin was moderately positive only for younger patients. Both tests (especially the Lanthony 40 Hue) resulted to be highly specific and could be used for the clinical study of colour vision losses in diabetic patients.

Adult

The X-Chrom lens. On seeing red.

A broadband red filter placed over one eye will have the effect of improving the ability of certain color vision defectives to name colors correctly. A red-tinted contact lens will have the same effect; such a device is marketed under the name, the X-Chrom lens. In this article, the author examines the basic properties of color vision defects, explains the optical effect of the red filter, and reviews several studies which evaluate the effect of the X-Chrom lens. He concludes that while the lens may allow the wearer to achieve a better score on certain color vision tests, it does not actually correct color vision in the natural environment. Deleterious effects of wearing a red filter are also discussed. It is advised that patients wearing the X-Chrom lens be fully apprised of its limitations and of dangers that may be created by the associated visual distortions.

Color Perception Tests

Autosomal recessive incomplete achromatopsia with deutan luminosity.

Four patients in three different families had a form of autosomal recessive incomplete achromatopsia not previously described. The visual acuity was 6/18 to 6/60 (20/60 to 20/200) with minimal ophthalmoscopic abnormality and normal fluorescein angiogram. The photopic electroretinographic responses were present in all four patients; the fusion rate of 60 Hz was only slightly subnormal. The high-intensity scotopic response was subnormal. The patients failed color screening plates and accumulated over 400 errors with scotopic axis on the Farnsworth-Munsell 100-hue test. The Rayleigh match was abnormal, displaced toward the red primary, but with normal luminance. The photopic luminous efficiency function was similar to that of the deuteranope. Color matching revealed a trichromatic form of color vision mediated by long wavelength and short wavelength cones, and a rhodopsin receptor.

Adolescent

Isolating the color vision loss in primary open-angle glaucoma.

We evaluated the results of Farnsworth-Munsell 100-Hue tests in age- and lens density-matched eyes of normal subjects, glaucoma suspects, and patients with primary open-angle glaucoma. With these controls in place, no significant correlation between the test results and age or between the test results and lens density was found. However, a significant difference in the total error scores on the 100-Hue test remained. This difference could not be explained by pupil size or medications taken. We concluded that color vision loss in glaucoma is in part attributable to the disease process and cannot be explained solely on the basis of changes in age and lens density.

Aged

The influence of homonymous visual field disorders on colour sorting performance in the FM 100-hue test.

An influence of visual field disorders on sorting performance in the FM 100-hue test is reported. Patients with left-sided field disorders performed worse in the conventional testing direction, i.e. from left to right, compared with patients with right-sided defects. Reversing the direction of sorting led, however, to a similar impairment in patients with right-sided field defects. Observations in normals tested under different conditions of hue sorting support the view that the difference obtained cannot be accounted for by a hemisphere difference in colour processing but by the strategy adopted by subjects.

Adolescent

[Blue cone monochromasia: diagnosis, genetic counseling and optical aids].

Cone and rod functions of three blue cone monochromats (age 13-20, male) from three different families were investigated. In contrast to rod monochromats, they lack prominent nystagmus. Color matches as determined using the Nagel anomaloscope came close to those of rod monochromats but the green primary appeared slightly brighter to them. In color discrimination tests (Farnsworth-Munsell 100-hue and Panel D-15 desaturated), maximum confusion followed protan rather than scotopic axes. Measurements of spectral sensitivity revealed action spectra exclusively of blue sensitive cones, even under conditions that should isolate green- or red-sensitive cones. After 20 minutes of dark adaptation, rods determined the spectral sensitivity function. Transient tritanopia, which in normals results from the interaction between cones sensitive to short and long wavelengths, was completely absent in blue cone monochromats. Visual acuity (Snellen charts and contrast gratings) revealed values between 20/200 and 20/60. Recognition of high-spatial low-contrast gratings was improved by blue cut-off filters (Schott BG 28) and considerably worsened by yellow cut-off filters (Schott OG 510). Since alteration of visual acuity induced by cut-off filters was not found in rod monochromats, this two-filter test is a means of differentiating quickly between rod achromats and blue cone monochromats. As the mode of inheritance is autosomal recessive in rod achromats and x-linked recessive in blue cone monochromats, differential diagnosis is important for correct genetic counseling.

Adult

Farnsworth-Munsell 100-hue test for patients with diabetes mellitus.

We evaluated 164 eyes of 87 patients with diabetes mellitus compared with 50 eyes from 25 healthy subjects as the control group. We compared 87 patients with diabetes mellitus (164 eyes) in relation to their duration of diabetes, fundus findings, visual acuity, and color vision defects. In all patients, color vision defects were determined using the Farnsworth-Munsell 100-hue test, and the total error score was established on the basis of age norms from subjects without diabetes. No color vision defect was detected in the control group. In the diabetic group, fundus degeneration and color vision defects were observed and correlated with the duration of diabetes. The dominant color defect was of the blue-yellow type.

Adolescent

Computer analysis of Farnsworth-Munsell 100-hue test.

Color vision abnormalities indicated by the Farnsworth-Munsell 100-hue Color Vision Tests (FM-100) were analyzed by computer to better characterize and group congenital and acquired color vision disorders and to help establish statistically significant diagnostic criteria. Standard evaluation of the FM-100 is by axis and error score calculations. A method has been established for computer-averaging many tests from patients with the same color abnormalities determined by history, standard FM-100 and Nagel anomaloscope. The computer calculated an average error score and standard deviation for each of the 85 color caps. Every time a new patient was evaluated for color vision abnormality, his score was compared with averaged tests with common diagnoses, by calculating distance scores. The averaged test with the lowest distance score consistently tended to coincide with the diagnosis. An analysis of 130 FM-100 color tests found technician-calculated error scores to be incorrect, although usually minor, in 40% of the tests. The computer-calculated axes agreed well with the technician's estimates. The distance scores predicted the diagnosis accurately 89% of the time. Many errors were due to the small number of protanopes averaged and inability to distinguish trichromats from dichromats.

Color Perception Tests

X-linked incomplete achromatopsia with more than one class of functional cones.

Five affected males in the fifth generation of a large pedigree of X-chromosomal incomplete achromatopsia were tested. All had SWS cone function. A 19-year-old affected man was a classical blue cone monochromat on color matching and spectral sensitivity. A 16-year-old boy showed evidence of a long wavelength sensitive cone active in 8 degrees color matches. With a blue-green background, his cone spectral sensitivity function peaked near 550-560 nm. Three younger boys, aged 7-10 yrs were evaluated only with color matching. All showed evidence of long wavelength cone function with an 8 degree field and one showed long wavelength cones in 2 degree matches. An independent observation concerning the family was the finding that deuteranomaly was introduced in the third generation. The fourth generation women, all obligate carriers of X-linked achromatopsia, had a 0.5 chance to carry deuteranomaly. Neither carrier state per se is usually associated with expression of deuteranomaly. Three of the five tested expressed deuteranomaly. This finding of deuteranomaly in the carrier females might be a consequence of a double carrier state indicating association between the genes for deuteranomaly and X-linked achromatopsia.

Adolescent

Traumatically acquired color vision defect.

A 24-year-old man acquired a color vision defect shortly after an accident in which he struck the back of his head. Results of the Farnsworth-Munsell 100-hue test showed that the patient had poor color discrimination in both eyes. His color matches on the Nagel anomaloscope suggested a red/green disturbance. Results from increment threshold testing demonstrated on absence of the blue mechanism. Results of field sensitivity measurements confirmed that foveal vision was mediated by the red or green mechanism. This case showed both similarities and differences to previously reported cases of acquired color vision defects secondary to cortical trauma.

Accidents, Traffic

[Cerebral achromatopsia (symptoms, course, differential diagnosis and strategy of the study). I].

To the patient, the sudden onset of cerebral achromatopsia is like switching to black and white on a color TV. As a rule, the defect arises due to bilateral ischemic infarction in the inferior occipitotemporal region. Bilateral upper homonymous quadrantanopsias usually leave the macula more or less unimpaired, so that visual acuity is largely preserved. Prosopagnosia and loss of topographic memory are often associated with central achromatopsia. Investigations of color vision must include color-naming procedures and largefield tests in addition to the conventional methods. Color-naming tasks are indispensable in differentiating cerebral achromatopsia from the aphasic and disconnective types of color anomia. The authors' recommended strategy for investigating color vision relies on records of a case of cerebral achromatopsia obtained six months and two years, respectively, after the onset of symptoms. In addition to the above-mentioned procedures, spectral increment thresholds on white and colored backgrounds were determined. For the first time in cerebral achromatopsia, examinations with large-field spectral matches were performed using the projection anomaloscope. Large-field tests are indispensable for monitoring recovery in cases of central achromatopsia. In the author's patient, recovery of blue-green discrimination was far more complete than that of red-yellow-green discrimination, and for both conditions large-field color vision was far superior to small-field.

Aged

Luminance noise and the rapid determination of discrimination ellipses in colour deficiency.

A computer-controlled test of colour vision is described, in which luminance noise and masking contours are used to ensure that the subject's responses depend on chromatic signals. The test avoids the need--common to most computer-controlled tests--to define equiluminance for the individual subject before the colour test itself can be administered. The test achieves a good separation of protan and deutan subjects and reveals the large range of chromatic sensibilities among anomalous trichromats. As a population, dichromats had higher thresholds on the tritan axis of the test than did normals. In an extension of the test, full discrimination ellipses were measured for normal and colour-deficient observers. The nature of anomalous trichromacy is discussed and the possibility is raised that hybrid genes, resulting from genetic recombination, may code for incorrectly labelled or functionally impaired molecules.

Adolescent

Color vision screening of young children.

Early detection of congenital color vision defects is desirable, but school screening studies have been stymied by lack of a suitable test. We evaluated a new color vision test, the APT-5, for use by volunteer screeners in schools and preschools. The screeners tested 1794 children, ages 3 to 13 years, and found the APT-5 easy to use with young children ages 5 years and up. Children who failed the screening were recruited for diagnostic color vision testing; for the children ages 5 to 13 years, 56% of those who failed the screening were successfully recruited. Data analysis indicated that the false-positive rate in this age group was 1% to 2%, and that for boys in this age group the positive predictive value was 71% to 81%. Retest data indicated that most false-positives were not due to the test itself, but to other factors in the school screening situation. Two thirds of all children scored as abnormal by anomaloscopy were simple deuteranomalous, indicating that the APT-5 effectively identified even mild color defects. The results of this trial indicate that the APT-5 is suitable for school color vision screening of children ages 5 years and up.

Adolescent