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In general the statements in the manual of the New Color Test are confirmed, but there is no exact correlationship between the AOH-R-R classification and the NCT classification. There is a gradual increase in sensitivity from the AOH-R-R, via the panel D-15 and the NCT 6/2 to the desaturated panel 8/2. Thus, if the panel 8/2 result is normal the NCT 6/2 yields no further information.
A clinical and neuro-ophthalmological examination using tests of visual acuity, quantitative visual field analysis, tests of colour discrimination, ophthalmoscopy, and pattern visual evoked responses was performed on 2 symptomatic and 16 asymptomatic members of a family with Leber's optic neuropathy. The visual evoked responses were abnormal in the 2 clinically affected males and in 1 asymptomatic male. Tests of colour discrimination with Ishihara plates, the Farnsworth-Munsell 100 hue test, and the Nagel anomaloscope revealed abnormalities in 8 asymptomatic family members, with the Farnsworth-Munsell test proving to be the most sensitive to mild abnormalities of colour discrimination. The occurrence of detectable neuro-ophthalmological abnormalities within this family is in keeping with the expected pattern of transmission of Leber's optic neuropathy. The significance of detection of presymptomatically affected cases and asymptomatic carriers is discussed.
After viewing red vertical stripes and green horizontal stripes, the eye subsequently views white vertical stripes as greenish and white horizontal stripes as pinkish. It has been theorized that this phenomenon, known as the McCollough effect, is related to long-tern adaptation of cells tuned for both color and orientation. Such cells have been found in the visual cortex of the rhesus monkey. We asked whether rhesus monkeys, like man, experience a McCollough effect. Two humans and two rhesus monkeys were adapted by requiring them to fixate a spot moving slowly across alternating horizontal and vertical gratings of complementary color. Following adaptation, a test grating whose color changed from red to green or green to red was presented. Humans and monkeys were instructed or trained to release a response lever during the interval that the grating was white. After adaptation, there were orientation-specific changes in all four subjects' responses as would be predicted if both man and monkey were experiencing a McCollough effect.
Color constancy is our ability to perceive constant surface colors despite changes in illumination. Although color constancy has been studied extensively, its mechanisms are still largely unknown. Three classic hypotheses are that constancy is mediated by local adaptation, by adaptation to the spatial mean of the image, or by adaptation to the most intense image region. We measure color constancy under nearly natural viewing conditions, by using a design that allows us to test these three hypotheses directly. By suitable stimulus manipulation, we are able to titrate the degree of constancy between 11% and 83%, indicating that we have achieved good laboratory control. Our results rule out all three classic hypotheses and thus suggest that there is more to constancy than can be easily explained by the action of simple visual mechanisms.
To find out the most sensitive parameter of early toxic ocular changes, a group of patients was extensively examined at regular intervals during therapy with ethambutol. Colour vision abnormalities could be detected using the desaturated panel of Lanthony in the presence of normal visual acuity, normal visual fields, normal visual-evoked potentials and a normal panel D-15 test. Major blue-yellow errors were found in treated patients without visual complaints as well as in a group of healthy volunteers, but there was a significant difference between both groups. In a later stage of intoxication, blue defects, red-green defects or tritanomalous defects can be observed, together with other symptoms of ocular intoxication.
The popularity of yellow goggles for outdoor activities has long been a paradox to visual scientists as previous tests of their effectiveness have failed to show any visual advantage. The achromatic/chromatic theory of color vision suggests a possible solution to the paradox which was tested by measuring reaction times to spatial frequencies of varying contrast. Reaction times were faster with yellow goggles than with luminance-matched neutrals under certain conditions. These conditions included frequencies in the middle of the range of human sensitivity and, specifically, the lower contrasts of these frequencies. The theoretical and practical applications of the results are discussed.
PURPOSE: Most color vision tests require a high level of cognitive ability and as such are problematic for preschool children and multiply challenged individuals. Our goal was to design a color vision test for these groups and evaluate the clinical utility for preschool children. METHODS: The University of Waterloo Colored Dot Test (UWCDot) for Color Vision Testing requires the subject to distinguish a colored disc from seven gray discs. The target disc was a Munsell color along the deutan, protan, or tritan confusion line with gray. The first phase estimated the sensitivity and specificity of the test for adults. Thirty-one adults with normal color vision and 21 adults with congenital red-green defects participated. In the second phase, the utility of the UWCDot test for screening preschool children was determined. Subjects were 281 males and 269 females aged 2.5 to 5 years with normal vision. Their color vision was also assessed with the Standard Pseudoisochromatic Plates, Part 1 (SPP1). RESULTS: The sensitivity and specificity of UWCDot for adults approached the values for the desaturated D-15 when subjective responses were scored. Monitoring fixational eye movements produced sensitivity and specificity values that were similar to the anomaloscope. After adjusting the scoring criterion for the preschool children by using the females as a control, 2.9% of the males were identified as red-green deficient, 1.8% were blue-yellow deficient, and 3.2% had an unclassified deficiency. By definition, 1% of the females failed the test. Counting fixational eye movements was not a useful scoring method in the preschool children. Comparisons with SPP1 indicated that the UWCDot uncovers approximately 35% of the individuals with definite red-green color vision defects. CONCLUSIONS: Our results indicate that the UWCDot is capable of detecting approximately 35% of the preschool children who have a congenital red-green color vision defect. These individuals are likely to have a more severe deficiency.
The Farnsworth-Munsell-100 Hue-Test (FMT) shows an increasing importance for judgement of colour vision disturbances and drug side effects on the ocular system, respectively. Because of the widening of caffeine use, the high incidence of intake of oral contraceptives and the absence of prospective studies, it is necessary to do it to investigate the possibility of influences on colour vision. 206 test persons of both sexes took part in our investigation with the FMT to clear influences of caffeine, oral contraceptives and the combination of both of them. A remarkable result is that caffeine with intake of oral contraceptives diminished the ability of colour discrimination in a wide range of visible coloured light. These investigations are in addition to views known from relevant literature.
Quantitative analyses of color vision using the Farns-worth-Munsell 100-hue test confirm that the mode of inheritance is important for the prognosis of retinopathia pigmentosa. Cases involving the autosomal dominant mode of inheritance are characterized by slight functional losses whereas patients with the autosomal-recessive or the X-chromosomal-recessive mode of inheritance show pronounced defects in the photopic system. With time the degeneration affects the blue, the green and finally the red areas of the color spectrum.
Over the whole course of dark adaptation, light- and color detection thresholds were measured. At 6 degrees in the nasal visual field, the effect of wavelength was examined. After the rod-cone break (Kohlrausch kink), the color threshold began to rise while the light threshold was progressively decreasing. The rise of the color threshold was more remarkable as the test wavelength was more close to the peak wavelength for rod sensitivity. With green test light, the sensitivity difference of retinal position was investigated. The rise of the color threshold was more prominent at the retinal position where rods were more densely packed. Finally, the Stiles-Crawford effect was examined with a green test light at 12 degrees in the nasal visual field. This effect appeared for the color threshold over the whole course of dark adaptation but not for the light threshold even before the rod-cone break. It was concluded that the rod activation interferes with cone sensitivity and the interference effect becomes stronger as rods become progressively more dark adapted, and that the rod system is also acting even before the rod-cone break.
36 soldiers were given the Farnsworth-Munsell 100-Hue Test to: (1) validate published research in which a field-independent group had been found to be superior to a field-dependent group in discriminating colors; (2) investigate unpublished findings in which substantial improvement had been shown in color discrimination performance over five trials of the 100-Hue test; and (3) determine the effect of low illumination (25 w, 40 w, and 60 w) on performance of the color discrimination task. A field-independent and a field-central group each performed significantly more accurately than a field-dependent group under all illumination conditions, and seven repeated administrations at 100 w resulted in significant improvements in performance. Color discrimination in the 25-w condition was significantly poorer than in the other illumination conditions. The implications are discussed.
AIM: To correlate the phenotype of X linked congenital stationary night blindness (CSNBX) with genotype. METHODS: 11 CSNB families were diagnosed with the X linked form of the disease by clinical evaluation and mutation detection in either the NYX or CACNA1F gene. Phenotype of the CSNBX patients was defined by clinical examination, psychophysical, and standardised electrophysiological testing. RESULTS: Comprehensive mutation screening identified NYX gene mutations in eight families and CACNA1F gene mutations in three families. Electrophysiological and psychophysical evidence of a functioning but impaired rod system was present in subjects from each genotype group, although the responses tended to be more severely affected in subjects with NYX gene mutations. Scotopic oscillatory potentials were absent in all subjects with NYX gene mutations while subnormal OFF responses were specific to subjects with CACNA1F gene mutations. CONCLUSIONS: NYX gene mutations were a more frequent cause of CSNBX than CACNA1F gene mutations in the 11 British families studied. As evidence of a functioning rod system was identified in the majority of subjects tested, the clinical phenotypes "complete" and "incomplete" do not correlate with genotype. Instead, electrophysiological indicators of inner retinal function, specifically the characteristics of scotopic oscillatory potentials, 30 Hz flicker and the OFF response, may prove more discriminatory.
The effect of acute air-hyperbarism (maximal 520 kPa), normobaric low and high FIO2 levels (minimal 0.1, maximal 1.0) and hyperbaric oxygen (HBO2) on the red-green sensitivity ratio (rgSR) and on color discrimination for foveal vision were studied. Effects were quantified by measuring the red-green flicker (16 Hz) fusion point for normals with the Oscar tester (Am J Optom Physiol Opt 1983; 60:892-901). Color discrimination was examined with the Lanthony's Desaturated 15 Hue test After 15-20 min of exposure rgSR is enhanced 4% (relatively increased red sensitivity) by normobaric acute hypoxia, and reduced 4% by normobaric hyperoxia (FIO2 = 1.0), but HBO2 gives a smaller reduction, and air-hyperbarism (FIO2 = 0.21) has no effect. Hypercapnia (increased FICO2), normobaric hypoxia (reduced FIO2), and HBO2 increase the duration of the Lanthony's test about 20-40%, but the number of errors were practically unchanged. The reduced effect during HBO2 upon rgSR is attributed to an opposing effect of hypercapnia. The absence of an effect during air-hyperbarism is probably due to a suppression by nitrogen of the effect of high PO2. In general, during moderate air-hyperbarism and HBO2 color vision seems to be normal, but evaluation of the colored scene is probably less stable and slightly slower.
A new test of colour vision using computer graphics has been used to obtain quantitative estimates of colour contrast sensitivity in ophthalmologists before and after they have treated patients by argon laser retinal photocoagulation. The colour vision of all subjects is normal when tested with the 100-hue test and HRR (Hardy, Rittler, Rand) plates, but colour contrast sensitivity measured along a tritan colour confusion line is selectively impaired after a treatment session. No such change occurs after a medical session spent examining patients with a fundus camera. In younger ophthalmologists the sensitivity recovers several hours after the treatment session ends, but in some persons there is a prolonged and possibly permanent elevation of threshold.
The colors of Benham's Top [pattern induced flicker colors (PIFCs)] were matched with color stimuli provided by a computer aided color mixer. Subjects viewed a series of specifically modified black and white disks and matched the resulting subjective color with a comparison field containing the color generated by additive mixing. Different phase relations between the apparently colored ring and the surround were tested. The color loci of all PIFCs were found to lie on a plane in receptor three-space which is given by the axis of the shortwave receptor excitation and a vector given by combining the middle and long wave receptor excitation directions in a fixed ratio of nearly 1:1. From the orientation of this plane it can be deduced that the blue-yellow opponent process (the blue-on-center cells) alone accounts for the different PIFCs.
The surface-mode property of "blackness" is induced by simultaneous contrast with an adjacent, more luminant surround. As numerous studies have shown, the degree of blackness induced within an achromatic test field is a function of the relative luminance of the adjacent chromatic inducing field, but not of its hue. But in the converse case of chromatic test fields, susceptibility to blackening has been reported to vary with wavelength. The present study investigates this possibility, that some wavelengths are more susceptible. We also questioned whether "white" and "black" sensory components function as opposites in blackness appearance. We recorded the appearance of a central monochromatic test field of constant luminance (10 cd/m2), with wavelength ranging across the visible spectrum, while a broadband white annulus was set to six luminance levels ranging across three log steps. Three color-normal observers followed a color-naming technique. All six opponent-hue names and their combinations were response options; blackness and whiteness in the test field could therefore be reported independently. Of primary interest were the achromatic responses. When represented within a multidimensional space, these revealed the "white-to-black" dimension but in addition a quality (dimension) of "desaturation." Compared against chromatic properties of the test field, the results provide evidence that blackness is a function of inducing field brightness (not luminance). This result is in accord with observations made by Shinomori et al. (1997) using a different procedure. We conclude that blackness induction occurs at a stage of visual processing subsequent to the origin of the brightness signal from a combination of opponent-process channels.
BACKGROUND: A very important aspect of visual performance to consider, for present and future recommendations regarding aircrew visors, concerns their impact on color vision. The literature has remained mostly inconclusive with respect to the human perceptual process of colors during actual mission employment. OBJECTIVE: This study uses active duty military aircrews to provide objective and valuable information on the effects of Short Wavelength Absorbing Filters (SWAFs), such as the High Contrast Visor (HCV), and some selected waveband type Laser Eye Protection (LEP) visors on color vision. It provides a direct comparison of several current and proposed aircrew eye protective visors with respect to their effects on color vision. The data analyzed in this study will also be used to support a recommendation regarding a new optimal visor for aircrew wear during air to air (and ground) engagements, for sun protection, and possible visual enhancement in order to improve user compliance. METHODS: Seven volunteers on active flying status each underwent comprehensive color vision testing with and without seven of the U. S. Air Force's (USAF's) current or proposed aircrew visors/filters. Spectral transmissions of these visors/filters were obtained to identify and determine their individual characteristics which included their ability to induce acquired color vision decrements in "color normal" individuals. RESULTS: The widely utilized USAF HCV significantly degraded color vision more than luminosity matched neutral density visors. Abrupt color vision decrements for specifically fielded LEP visors were also noted. Their objective data supported theoretical and speculated color vision effects. Even though low transmittance neutral density visors did have some effect on color vision, decrement severity was not considered significant enough to affect overall performance during color vision testing. CONCLUSIONS AND DISCUSSION: Because of their ability to significantly affect color vision, concerns regarding the use of HCV and LEP visors should entail age, baseline color vision, environmental, and mission factors. Further testing should be done to evaluate the definitive effects that these visors actually have on the recognition of color symbology of Multi Function and Electronic Flight Information Displays. Findings in this study also support theoretical opinions that encourage the fielding of a neutral density filter (mildly tinted) with an overall transmission of 25-49%. Its use by flyers during low and bright illuminant conditions may greatly enhance visual performance by encouraging wearer compliance while allowing colors to be perceived normally.
The so called "benign" central serous retinopathy is associated in healed forms with frequent and troublesome visual function impairment. The abnormalities are still more severe after diffuse retinal pigment epitheliopathy. Snellen visual testing is relatively imprecise index of visual function, so it does not permit to appreciate the subtle visual disturbances experienced by these patients. We evaluated visual function disability with static automatized perimetry and contrast sensitivity in 30 patients with diffuse epitheliopathy in a cicatricial phase. Colour vision was also evaluated by 16 patients after central serous retinopathy. The results of this study are examined and discussed.