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PubMed2002

Color discrimination in schizophrenia.

Neuropsychiatric conditions that involve dopaminergic depletion have been associated with color discrimination deficits along the blue-hue (tritan, or short-wavelength-sensitive) axis. Because dopamine dysregulation may be a major factor in schizophrenia, we investigated color vision in this disorder. The performance of males with schizophrenia (SZ, n = 16) and normal male control subjects (CS, n = 14) was evaluated on five measures of color discrimination. SZ made more hue discrimination errors than CS, but no pattern emerged regarding a hue-specific axis of deficit. Dosage of anti-psychotic medication was not correlated with performance on hue discrimination. These results suggest that in medicated patients with schizophrenia, the dopaminergic disturbance, which may involve system hyperactivity, does not produce tritan-specific color deficits that have been observed in disorders involving dopaminergic hypoactivity.

Adult↗
PubMed1990

Hue discrimination and S cone pathway sensitivity in early diabetic retinopathy.

Measures of hue discrimination and M (green) and S (blue) cone pathway sensitivities were compared in a group of 24 diabetics with either early background retinopathy or no retinopathy. The Farnsworth-Munsell 100-hue test was used to measure hue discrimination, and a two-color increment threshold technique was used to measure S and M cone pathway sensitivities. The results were compared to the level of diabetic retinopathy, to the degree of macular edema, and to the duration of the disease. No significant correlation was found between the Farnsworth-Munsell 100-hue error scores and the level of retinopathy; S cone pathway sensitivity loss, however, correlated significantly with both the level of retinopathy and the degree of macular edema. Our results indicate that measurements of S cone pathway sensitivity using an increment threshold technique provide a more sensitive method than hue discrimination for detecting color vision deficits in early diabetic retinopathy.

Adult↗
PubMed1986

The ability of protan color defectives to perform color-dependent air traffic control tasks.

Air traffic controllers perform a variety of tasks which require them to identify, discriminate and name colors. Qualification standards for this occupation require applicants to have normal color vision. Although the validity of this standard has been questioned, Adams and Tague recently presented evidence in this Journal (1985;62:744-50) that protanopes cannot perform color-dependent air traffic control tasks reliably. In our study, the results of 7 severe and 2 moderate protans are compared to those of 78 normals on a set of tasks which simulated critical tasks performed daily by air traffic controllers. The four tasks included discriminating red from black pencil marks on flight progress strips, color-naming of 1(0) and 0.1(0) discs, and identification of colored line segments embedded in a multi-colored background. The severe protans we tested performed none of the tasks as well as normals. While the performance of the moderate protans was better, statistical conclusions could not be drawn. Our set of tasks bears many similarities to the set used by Adams and Tague and it appears we were trying to answer the same questions. The results of the two studies are similar and the conclusions are the same: severe protans cannot perform color-dependent air traffic control tasks reliably.

Accidents, Aviation↗
PubMed1990

Striking absence of long-lasting effects of early color deprivation on monkey vision.

A monkey (Macaca fascicularis) spent its first three months under far red illumination that made color vision impossible. It developed normal spectral sensitivity. In the present study we examined two aspects of color vision that presumably reflect cortical connectivity. In the first part of this article we show that chromatic induction was also unaffected: a blue surrounding made a gray target appear to be yellow to the monkey. At five months of age, the deprived monkey did not readily use color to recognize objects, although it was able to do so if necessary. In the second part of this article we show that, as an adult, the monkey was quite willing to use color to categorize objects. We conclude that early color deprivation does not result in long lasting deficits in color vision.

Aging↗
PubMed1995

Discrimination of binocular color mixtures in dichromacy: evaluation of the Maxwell-Cornsweet conjecture.

We tested the Maxwell-Cornsweet conjecture that differential spectral filtering of the two eyes can increase the dimensionality of a dichromat's color vision. Sex-linked dichromats wore filters that differentially passed long- and middle-wavelength regions of the spectrum to each eye. Monocularly, temporal modulation thresholds (1.5 Hz) for color mixtures from the Rayleigh region of the spectrum were accounted for by a single, univariant mechanism. Binocularly, univariance was rejected because, as in monocular viewing by trichromats, in no color direction could silent substitution of the color mixtures be obtained. Despite the filter-aided increase in dimension, estimated wavelength discrimination was quite poor in this spectral region, suggesting a limit to the effectiveness of this technique.

Adult↗
PubMed2001

Study of colour discrimination with comb-filtered spectra.

Techniques that involve the use of comb-filtered spectra to study human colour vision have been developed in previous work (Bonnardel, V., Bellemare, H., Mollon, J.D., 1996. Measurements of human sensitivity to comb-filtered spectra, Vision Research 36, 2713-2720; Bonnardel, V., Ruderman D.L., Barlow, H.B., 1997. A fast determination of the Spectral Modulation Sensitivity Function: a comparison between trichromats and deuteranopes. In: C.R. Cavonius (ed.), Color vision deficiencies XIII. Dordrecht: Kluver 415-424). These techniques are applied in the present study to measure colour discrimination among deuteranomalous observers and normal trichromats, with the aim of determining the spectral position of the anomalous cone fundamentals. Results show that comb-filtered spectra are useful in determining the extent to which variability in colour discrimination among anomalous and normal trichromatic colour observers is accounted for by the spectral properties of photoreceptors.

Color Perception↗
PubMed1993

Evidence from human electroretinogram A and off responses that color processing occurs in the cones.

PURPOSE: To investigate two apparent anomalies of the human electroretinogram: the "on" and "off" components of the cone based PIII are unequally sized, and transitions from red to green, which are electroretinographically silent, yield reverse transitions (green to red) in which a-waves develop. METHODS: Ganzfeld electroretinograms were obtained with intense 100 msec flickering flashes from red and green light-emitting diode. Such stimuli light-adapt the retina, and the responses are caused by the excitation of long and medium wavelength cones. RESULTS: In the 10-20 msec after the beginning of a flash (black to green or black to red) the beginning of rapid receptor-generated a-wave is seen. Ten to twenty milliseconds after the end of the flash, the beginning of a rapid positive-going off response, also derived from receptors can be seen. If the retina is stimulated by the abrupt change from one wavelength of light to another (eg, from "green" to "red"), at times > 20 msec after the change there are always slow changes in potential (presumably caused by postsynaptic activity) regardless of the relative intensities of red and green. However, if the two light intensities are adjusted appropriately, 10-20 msec after the transition from green to red no electroretinographic a-wave (or off response) develops--the transition is "silent." When the transition reverses (changes back from red to green), an a-wave occurs. In the same way if a red-to-green transition is made silent by altering the relative light intensities, the green-to-red reversal evokes an a-wave. This occurs for numerous pairs of red and green intensities. Rod intrusion or minor electroretinogram components do not explain this result. The relative red:green intensity in two color-anomalous subjects is different to that in three normal subjects. The rule for a silent transition is that the decrease in excitation in one cone type should be twice the increase in excitation in the second cone type. CONCLUSIONS: The most likely cause is a reduction in the amplitude of cone receptor potentials 20-50 msec after the onset of the stimulus, caused by a sign-reversing feedback mechanism such as that described in amphibians. This implies that the chromatic signals for color vision required by theorists are partly generated in the cones.

Color Perception↗
PubMed1996

Clinical study of a large family with autosomal dominant progressive cone degeneration.

PURPOSE: Autosomal dominant cone degeneration is an uncommon disorder characterized by progressive photophobia, hemeralopia, decreased central vision, and dyschromatopsia. To better understand the variable expressivity of autosomal dominant cone degeneration, we studied a single, large family. METHODS: We performed comprehensive ophthalmic examinations, full-field electroretinography, foveal electroretinography, and color vision studies on 73 family members. RESULTS: Of the 73 family members, 34 were affected. Symptoms generally began in the first decade of life and slowly progressed into midlife. Ophthalmoscopic findings consisted primarily of macular granularity or central macular atrophy. The photopic full-field electroretinogram was important in establishing the diagnosis, although the results of the electroretinographic measurements varied across individuals. Either the foveal electroretinogram amplitudes were abnormally low or the foveal/parafoveal ratio was abnormal in all affected subjects. CONCLUSIONS: No single test or finding was completely sensitive or specific for accurate diagnosis of autosomal dominant cone degeneration. Especially in the more mildly affected subjects, a constellation of symptoms, findings, and test results were used to diagnose autosomal dominant cone degeneration accurately.

Adolescent↗
PubMed1990

Rod and cone pigments of the Atlantic guitarfish, Rhinobatos lentiginosus Garman.

Using both extraction- and micro-spectrophotometric (MSP) methods the visual pigment(s) from the rods and cones of the Atlantic guitarfish, Rhinobatos lentiginosus, were shown to be spectrally similar, if not identical (lambda max = 498-499 nm). Color vision, therefore, is unlikely unless mediated via colored oil droplets in the inner segments. The identical lambda max for the rod and cone pigments suggest that vision in both dim and bright light may correlate with the underwater spectrum over the depths and the times of day that guitarfish are active. The primary advantage of the blue-green sensitive visual pigments, we suggest, is to enhance the contrast of targets silhouetted against the background spacelight.

Animals↗
PubMed1996

[Assessment of vision disorders using color duplex ultrasonography].

Disturbed circulation is a common cause of visual impairment which time course and severity can vary. Prompt diagnosis and therapy are mandatory to restore visual function in cases of acute drop of vision. Color Doppler imaging is a noninvasive method to investigate blood-flow velocity. During the past years this method has been introduced into ophthalmology. For the first time it is possible to measure the blood-flow velocity in the ophthalmic artery, the central retinal artery and vein as well as the ciliary arteries to quantify the extent of impaired ocular circulation.

Glaucoma↗
PubMed1996

Color axis evaluation of the Farnsworth Munsell 100-hue test in primary open-angle glaucoma and normal-pressure glaucoma.

BACKGROUND: It was the aim of the present study to analyze a separate color-axis evaluation of the Farnsworth Munsell 100-hue test (FM 100) in primary open-angle glaucoma (POAG) and normal pressure glaucoma (NPG). PATIENTS AND METHODS: One eye of each of 112 individuals (age 35-65 years, visual acuity > 20/28, myopia < -7.5 D) was included. The groups consisted of 62 normal subjects and 50 glaucoma patients (33 POAG and 17 NPG). We evaluated the FM 100 overall error score and the error scores of the protan, deutan and tritan axes. The results were compared with perimetric (Octopus G1 mean defect) and morphometric data of the optic disc. RESULTS: All error scores were significantly higher in the glaucoma group than in the normal group. In an age-related evaluation, differences were significant in age groups above 45 years. No significant differences were found between the POAG and NPG groups. The sensitivity of the overall score to identify glaucoma was 62% (specificity 80%). In the glaucoma group the overall score and the protan score increased significantly with the mean defect (r > 0.3, P < 0.01). Several scores increased slightly with decreasing neuroretinal rim area, but not on a significant level. Separate color-axis evaluations did not show any stronger correlations and did not reveal any differences between POAG eyes and NPG eyes. This was true even for the tritan axis error. CONCLUSIONS: Although FM 100 error scores are higher in glaucoma eyes and increase with glaucomatous damage, they do not separate well. In the sample of this study, separate color-axis evaluation did not improve the diagnostic value. With the FM100 a different pattern of color vision defects in POAG and NPG eyes could not be detected.

Adult↗
PubMed2004

Orientational contrast sensitivity and chromatic contrast thresholds in multiple sclerosis.

PURPOSE: To investigate abnormalities of orientational contrast sensitivity (CS) and chromatic contrast threshold (CCT) in multiple sclerosis (MS). DESIGN: Case control study. METHODS: Nine subjects (mean age, 42 +/- 11 years; range, 20-62 years) with MS, an expanded disability status scale of 3 or less, and normal visual acuity (VA) (logarithm of the minimum angle of resolution [logMAR] VA less than.1) in the tested eye were age-matched with 20 controls. Achromatic CS and CCT were measured using static, computer-generated sinusoidal gratings displayed on a high-resolution monitor. The CS and CCT of each subject were determined using a randomized double-staircase reversal algorithm; CS was measured at five spatial frequencies with horizontal orientation and three with vertical orientation; CCT was measured along the red-green and tritan confusion axes. The sensitivity thresholds of subjects were examined in relation to the mean sensitivity of controls for each spatial frequency. RESULTS: Two subjects had loss of horizontal and vertical CS, and three had isolated vertical loss. When compared with the control mean, there were significant reductions in red-green (P =.016) and tritan (P =.016) discrimination thresholds. CONCLUSION: This study used a computerized psychophysical test designed to minimize many of the test errors associated with earlier studies. It provides confirmatory evidence that MS may be associated with a loss of orientational CS and color vision, in the absence of reduced VA.

Adult↗
PubMed1982

Psychophysical evidence for more than two kinds of cone in dichromatic color blindness.

Psychophysical evidence shows that at least some classically diagnosed dichromats have three cone types rather than two. The anomalous cones, previously thought to be absent, are less sensitive than normal cones to both spectral and temporal variations, and have spectral sensitivities like those of the abnormal cones of anomalous trichromats. These results are not consistent with either loss or replacement models of X-linked recessive color-vision defects, since some dichromats apparently have the same three photopigments as anomalous trichromats.

Color Perception↗
PubMed1979

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↗
PubMed1979

Congenital cone dysfunction.

Three patients with congenital cone dysfunction are described with their clinical findings, including electrophysiologic and color vision evaluation, diagnostic criteria, and rehabilitative regimes. A classification system for this rare spectrum of disorders is presented.

Adolescent↗