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PubMed1997

Spectral sensitivity in patients with dysthyroid eye disease.

The majority of patients with dysthyroid eye disease have an acquired colour vision defect. However, no psychophysical investigation of selective damage to colour or flicker pathways has been carried out. In order to clarify the nature of the visual pathology, we have used a psychophysical technique (spectral sensitivity) to selectively stimulate the chromatic and achromatic mechanisms. Spectral spots of size 1 degree presented at a rate of 1 Hz on a bright 1000 td white background are detected by the chromatic mechanism but a rate of 25 Hz reveals the achromatic mechanism. Fifteen patients (28 eyes) between the ages of 50-70 years were tested. The study showed that all patients had reduced spectral sensitivity, either 1 Hz, 25 Hz or both. The patients with reduced 1 Hz or 25 Hz spectral sensitivity only had a shorter systemic and ocular duration of the condition, had no proptosis, normal intraocular pressures in primary gaze, slightly higher intraocular pressures on upgaze, normal visual field plots and FM 100-Hue error scores higher than the normal age-matched values. The patients with reduced both 1 Hz and 25 Hz spectral sensitivities had a longer systemic and ocular duration of the condition, had proptosis, normal intraocular pressures in primary position, higher intraocular pressures on upgaze and higher FM 100-Hue error scores than the age-matched normals and those in Groups 1 and 2. A total of 50% of patients in Group 3 had defective visual field plots. These data suggest that there is a damage of the large achromatic fibres and small chromatic fibres in dysthyroid eye disease. The mechanism of the damage could be one of ischaemic or mechanical or both.

Aged↗
PubMed1986

City tests and information theory.

The responses of 455 male subjects on both editions of the City University Colour Vision Tests (City 1 and City 2) were recorded after the establishment of each subject's criterial status using the Nagel anomaloscope. Based on the Information Theory, each plate was assigned a contributory weighted score to the total test score. Using informational analysis, a cut-off point in test score separating normals and defectives was also determined for each test. This scoring system is an improvement on the existing (or manufacturer's) system. The analysis has also shown that the second edition (City 2) is a considerable improvement on the first (City 1). Despite this, even the improved City 2, like its origin, the D-15, is shown to be poorer than most of the commonly used PIC tests.

Adolescent↗
PubMed1977

The locus of unique green in deuteranomalous trichromats.

A method of color naming was used to determine the spectral locus for unique green (UG) as it was perceived by 20 color normals and 24 deuteranomalous trichromats. The loci for the normal group were distributed bimodally, as earlier investigators had reported, and a bimodal distribution was also found for the deuteranomalous group. In the latter group, UG was located at long wavelengths only by those who had been classified as mild deuteranomals according to several clinical criteria. Those who located UG at shorter wavelengths included individuals whose defects ranged from mild to severe. This result is discussed in the context of theories of deuteranomaly and is presented as further evidence for the existence of 2 types of deuteranomaly.

Adolescent↗
PubMed1987

Spectral characteristics of electroretinography in congenital red-green color blindness.

There are few conclusive electroretinography (ERG) studies comparing the spectral characteristics in deutans and normals in contrast to protans and normals. The difficulties of research on deutans were thought to be due to problems in detecting the very slight differences in the spectral characteristics between deutans and normal subjects. To record monochromatic ERG responses accurately in deutans, our time-locked scanning method was improved as follows: We used 12 interference filters for stimulus lights with narrow half widths (4-6 nm) and wavelengths of peak transmission arranged at intervals of 10 nm between 520 nm and 600 nm. Each stimulus light was strictly adjusted to an equal energy and checked simultaneously with ERG recordings. Contact lens electrodes were reformed for comfortable fitting to subjects' corneas. The time interval between each stimulation was set at 300 msec and one scanning of all stimulations took only 3.9 sec. ERG bp-waves were recorded in congenital color blindness by scanning monochromatic light stimuli, and spectral responses obtained could be evaluated as a spectral pattern. Different spectral patterns of responses from those of normal subjects and shift of the peak in the spectral response curves were obtained for congenital color blind subjects. The maximal responses were recorded at around 540 nm in protans and at 570-580 nm in deutans under white adaptation. Differences in the response curves were not found between dichromats and anomalous trichromats. Moreover, selective chromatic adaptation disclosed the separate responses of green cone and red cone systems. In normal subjects the peak of the spectral response curves was shifted to around 540 nm by red adaptation and to around 580 nm by blue adaptation. The spectral patterns changed so that they looked like the patterns under white adaptation of protans and deutans, respectively. But in protans and deutans the same spectral response patterns and almost the same wavelengths of the peak in the spectral response curves as those obtained under white adaptation were recorded under chromatic adaptation. This method provides the possibility of differentiating between red and green color blind subjects and normal subjects by the ERG. Defects or marked abnormality in the red cone system in protans and the green cone system in deutans can also be detected. Monochromatic ERGs of deutans were recorded under more intense red adaptation.(ABSTRACT TRUNCATED AT 400 WORDS)

Adolescent↗
PubMed1998

Can clinical colour vision tests be used to predict the results of the Farnsworth lantern test?

Clinicians usually do not have access to a lantern test when making an occupational assessment of the ability of a person with defective colour vision to recognise signal light colours: they must rely on the results of ordinary clinical tests. While all colour vision defectives fail the Holmes Wright Type B lantern test and most fail the Holmes Wright Type A lantern, 35% of colour vision defectives pass the Farnsworth lantern. Can clinical tests predict who will pass and fail the Farnsworth lantern? We find that a pass (less than two or more diametrical crossings) at the Farnsworth Panel D 15 Dichotomous test has a sensitivity of 0.67 and specificity of 0.94 in predicting a pass or fail at the Farnsworth lantern test: a Nagel range of > 10 has a sensitivity of 0.87 and a specificity of 0.57. We conclude that neither the D 15 nor the Nagel Anomaloscope matching range are satisfactory predictors of performance on the Farnsworth Lantern.

Color Perception Tests↗
PubMed1988

Sorsby's pseudoinflammatory macula dystrophy--Sorsby's fundus dystrophies.

The findings are presented on the updated Kempster pedigree with Sorsby's fundus dystrophy. The study confirms the features described in other families: autosomal dominant inheritance with complete penetrance, loss of central vision due to subfoveal ingrowth of new vessels, and progressive peripheral chorioretinal atrophy. By contrast to other reports the family in the current study have peripheral retinal dysfunction, a deposit of a subretinal yellow material throughout the fundus and a tritan colour defect, all prior to the loss of central vision; in some patients there was loss of central vision from atrophic disease, rather than from ingrowth of subretinal new vessels; and, there was a different temporal progression of the central subretinal neovascular complex. These features suggest the possibility of genetic heterogeneity.

Adult↗
PubMed1996

Cavernous hemangioma with cone dysfunction.

We report a 13-year-old male who complained of strabismus and low visual acuity in the right eye. Saccular aneurysms filled with dark-colored blood were noted in the upper nasal quadrant of the right fundus. Ishihara color plates and Lanthony's new color test revealed a red-green color defect. Cone response and 30-Hz flicker responses were nearly absent. Cavernous hemangioma of the retina is a rare vascular hamartoma; the associated findings show cone dysfunction concomitant with this peripheral lesion.

Adolescent↗
PubMed1995

Eigenvector interpretation of the Farnsworth-Munsell 100-hue test.

We measured the reflectance spectra for the 85 color caps of the Farnsworth-Munsell 100-hue test. Eigenvectors and eigenvalues of a correlation matrix of cone responses were computed, with the cone responses being determined from the 85 test caps, arranged in order (according to color) by means of a linear model. It is shown that the Farnsworth-Munsell 100-hue test can be simulated by use of eigenvectors of the cone responses. The eigenvectors can be interpreted as nonopponent signal and opponent color signals. The normal observer can determine the color of a cap by using two opponent color signals. For color-blind persons (dichromats) one or the other opponent signal is defective, and errors can occur during the test. The simulation results also suggest that eigenvectors can be used to predict results of arrangement tests similar to the Farnsworth-Munsell 100-hue test.

Color Perception↗
PubMed1983

Validation of the Holmes - Wright lanterns for testing colour vision.

The recently introduced Holmes - Wright Type A and Type B lanterns and the Farnsworth lantern were administered to 100 observers with normal colour vision and 100 observers with defective colour vision. With the fail criteria adopted, all normals passed the Holmes - Wright Type A lantern and with one exception all normals passed the Farnsworth lantern. However, 8% of normals failed the more difficult Holmes - Wright Type B lantern. It is noted that the normals who fail this lantern test appear to do so not because of poor colour discrimination but because the coloured stimuli presented by the lantern have a point brilliance close to the average chromatic threshold. About one-third of the colour vision defective group passed the Farnsworth lantern and between 14 and 17% passed the Holmes - Wright Type A lantern depending on the test procedure used. Only two mild deuteranomals in the sample of 100 colour abnormal observers succeeded in passing the Holmes - Wright Type B lantern. Dichromats and severe anomalous trichromats fail all three lanterns so that those who pass are all mild anomalous trichromats. A significant proportion of protanomals pass the Farnsworth lantern and some protanomals pass the Holmes - Wright Type A lantern despite their reduced sensitivity to red light and correspondingly reduced signal range for red signals.

Color Perception Tests↗
PubMed1978

Clinical experience with the Lovibond Colour Vision Analyser. Results from the examination of normal and congenital colour-deficient subjects.

The Colour Vision Analyser was used for testing 98 persons of both sexes, aged from 10 to 70 years, and recognized as normal by means of pseudo-isochromatic plates and an anomaloscope. A drop of the saturation thresholds from yellow to green and from blue to purple was observed from the age of 40 years. The saturation thresholds from yellow to green was found lower in every age group than that from blue to purple. Congenital colour defects could be completely distinguished from normal subjects. As for the classification in types, those diagnosed as deutan by means of the anomaloscope were also diagnosed as deutan by the Analyser, however, there were, among those diagnosed as protan by the anomaloscope, some subjects who were diagnosed as deutan by the Analyser. Nearly all cases could be classified as anopia or anomaly.

Adolescent↗
PubMed1993

Pattern of dysfunction in progressive cone dystrophies--an extended classification.

An extended classification for progressive cone dystrophies is proposed on the basis of the retrospective analysis of the clinical and electrophysiological findings obtained in a series of 91 patients with progressive cone dystrophies and of a review of the literature. This classification depends on the different patterns of electroretinographic responses. Four main categories and ten subgroups are distinguished. Generalized cone dystrophies are most frequent (76/91), affect all types of cones, and may be subdivided according to the degree of rod involvement. In selective cone dystrophies (8/91), the three cone types are affected differently as detected with the color electroretinogram. They are subdivided on the basis of the cone type predominantly involved. Additional inner retinal transmission defects may occur in cone dystrophies (3/91). They are identified by an alteration in the b/a-wave ratio on the electroretinogram and may affect the cone or rod pathway. Localized cone dystrophies (4/91) are limited to certain retinal areas.

Adolescent↗
PubMed1978

Colorimetry by a new principle.

A simple and informative method is described for determining the type and extent of color defects. The subjects' responses are registered automatically on a chromaticity diagram that is based on the newtonian model. Color defects are readily identifiable by a skewing of the normal central gray area toward the defectively perceived color. The examination permits independent variation of hue and saturation for each color and requires less than five minutes for the entire procedure. Unlike conventional color tests, the present method indicates exactly what colors are or are not seen at any level of saturation.

Adolescent↗
PubMed1981

Impaired color discrimination among viscose rayon workers exposed to carbon disulfide.

A possible effect of chronic carbon disulfide exposure on the optic nerve was studied by giving the Farnsworth Munsell 100-Hue Test for color discrimination to 62 exposed and 40 nonexposed men. Carbon disulfide exposure did not relate to specific pattern defects in color discrimination, but impaired color discrimination occurred significantly more often in the exposed group than among the referents. The abnormal findings suggest an impairment in the receptiveness of the ganglion cells or demyelination of the optic nerve fibers.

Adult↗
PubMed1995

Peripheral cone contrast sensitivity in glaucoma.

Colour vision tests for detection of glaucomatous damage frequently suffer from two problems: most tests are confined to foveal vision, whereas defects tend to appear first extrafoveally; and the modulation directions in colour space are not optimal. This paper deals with peripheral testing à la Yu, Falcao-Reis, Spileers and Arden [(1991) Investigative Ophthalmology and Visual Science, 32, 2779-2789], and investigates whether there are modulation directions that show preferential sensitivity reduction in glaucoma. In 14 eyes with early glaucoma, 17 risk eyes and 10 normals, 12 deg peripheral colour contrast thresholds were determined for L, M, S, L-M and L+M test directions. Threshold elevations were correlated in all test directions, with S modulation yielding the largest elevations.

Aged↗
PubMed1994

Colour vision screening in glaucoma: the Tritan Album and other simple tests.

Results from simple colour vision tests used for the detection of the Type III colour vision deficiency in glaucoma and ocular hypertension are presented. We assessed 49 patients with primary open angle glaucoma, 16 ocular hypertensives, 54 age matched normals and 50 young normal observers using six established tests and the recently introduced Tritan Album. This test was introduced specifically for acquired colour vision deficiencies. Results show in general that individual tests have low sensitivity and poor screening efficiency. The best screening efficiency was achieved by the City University Colour Vision Test and the AO HRR plate test, no acquired tritan defects were identified by the Farnsworth F2 plate, and the Tritan Album had very low sensitivity (the lowest excluding the F2 plate). Best results were obtained from a combination of City University and HRR test scores and this combination could provide useful additional data on colour vision in a glaucoma screening programme.

Aged↗
PubMed1986

Red-green mixture thresholds in congenital and acquired color defects.

A color television display was used to measure thresholds for mixtures of red and green on a white background; red and green components could be either incremental, decremental or zero. Ellipses are fitted to a plot of green contrast as a function of red contrast, and it is argued that the length of the ellipse is a measure of red-green color discrimination and the width of the ellipse is a measure of luminance discrimination. It is shown that the technique reliably distinguishes normals from congenital color defectives and also protan from deutan subjects. For some cases of acquired color defects (e.g. optic neuritis), there is a roughly equal loss of color and luminance discrimination whereas, in other cases (e.g., hereditary optic atrophies), the loss of color discrimination is much greater than the loss of luminance discrimination.

Adult↗
PubMed1986

Visual evoked response in syphilitic optic atrophy. A case report.

A case of neurosyphilis is described. The presenting symptoms were reduced visual acuity and impaired colour vision. The examination revealed bilateral optic atrophy and acquired red-green colour defect. A syphilitic aetiology was based on positive serological tests in blood and CSF, pleocytosis and increased total protein in the CSF. The abrupt decline in visual acuity was arrested by treatment with penicillin and systemic steroids, but normalization of vision was not obtained. All VER-records, of P2 latencies and morphologies were surprisingly normal, but the amplitudes were reduced.

Color Vision Defects↗
PubMed1994

Pathologic scotopization: a shortened Nagel-II anomaloscopic micro-screw method.

The Nagel-II micro-screw method uses eleven colour equations between 620 and 560 nm. The luminance settings are given and are based on the data of colour normal individuals. In the shortened version, intended to detect pathologic scotopization, it is ascertained at which position of the micro-screw the patient's colour adjustments drop beneath the level of 60 scale Units. A total of 64 patients was examined. 29 congenital colour defectives and 35 acquired colour defectives. With the shortened micro-screw method the patients can be divided into four groups: (1) a group without pathologic scotopization, which includes congenital protan defectives: (2) a group in which pathologic scotopization starts; (3) a group with evident pathologic scotopization, due to Stargardt's disease and other cone dystrophies; and (4) a group with complete pathologic scotopization, which includes the congenital achromats and the end-stages of the cone dystrophies.

Color Perception Tests↗