Congenital Colour Vision Deficiency Research Articles

Investigation of relationship between colour discrimination ability and stereoscopic acuity using Farnsworth Munsell 100 hue test and stereo tests

ObjectiveTo evaluate the effect of colour discrimination ability on the stereoscopic acuity by comparing individuals having congenital colour vision deficiency (CCVD) with healthy individuals. DesignA comparative study. ParticipantsThe study included 53 binocular males, of whom 26 (mean age, 36.04 ± 9.30 years) were in the healthy group and 27 (mean age, 33.04 ± 9.81 years) were in the CCVD group. MethodsThe following tests were used: the Ishihara pseudo-isochromatic plate test for detecting CCVD, the Farnsworth Munsell 100 (FM100) hue test for colour discrimination ability, the TNO and Titmus stereo tests for stereoscopic acuity. ResultsIn the CCVD group, 20 males were deutan and 7 males were protan. According to the FM100 hue test, total error score (TES), blue/yellow (b/y) local error score (LES), and red/green LES were significantly lower in the healthy group (30.23 ± 18.78, 15.15 ± 10.38, and 13.88 ± 11.93, respectively) than in the CCVD group (133.59 ± 67.45, 41.15 ± 22.03, and 89.15 ± 52.16, respectively) (p < 0.01 for each). The stereo test scores revealed significantly higher stereoscopic acuity in the healthy group (43.85 ± 33.92 arcsec for the TNO test and 40.00 ± 0.00 arcsec for the Titmus test) than in the CCVD group (93.33 ± 90.51 arcsec for TNO stereo test and 52.96 ± 24.62 arcsec for the Titmus test) (p < 0.05 for each). The TNO test score was significantly and positively correlated with the TES (r = 0.390, p = 0.049) and b/y LES (r = 0.490, p = 0.011) in the healthy group. ConclusionsColour discrimination ability affected stereoscopic acuity. Moreover, stereoscopic acuity increased with increasing colour discrimination ability, which could be originated from the b/y colour region.

Impact of congenital color vision defect on color-related tasks among schoolchildren in Durban, South Africa.

BackgroundPeople with congenital color vision deficiency can experience some difficulties with seeing colors in everyday life, and these problems vary according to the nature and severity of the defect, the individual’s circumstances and their ability to develop coping or adaptive strategies.PurposeTo determine the impact of congenital color vision deficiency on color-related tasks among Black South African schoolchildren.MethodsA cross-sectional descriptive study was conducted among 1305 public schoolchildren in Durban, South Africa. Structured questionnaires were administered to determine the difficulties they encountered in aspects of color matching and recognition.ResultsOf the 1305 schoolchildren who participated, 601 (46.1%) were boys and 704 (53.9%) were girls, with 29 (2.2%) having congenital color vision defects. The prevalence of congenital color vision deficiency was higher in boys (n=25; 4.2%) than in girls (n=4; 0.6%). A statistically significant proportion (P<0.0001) reported difficulties with color-related schoolwork and activities of daily living.ConclusionCongenital color vision deficiency affects many aspects of life and extends across play, sports, education, health and safety issues. Early detection of children with congenital color vision defect through regular school screenings is needed to offer affected children appropriate vocation and career guidance.

How colour palettes in maps are re-coloured by daltonization methods

Abstract. The ability of identifying objects and elements based on colour is important in order to decode the information in a map or other information graphics. For this reason, the colours need to appear correct and be perceived in the desired and intended way. Map reading is reported as a challenging task for people with impaired colour vision. In reviews of the challenges of colour vision deficiencies (CVD) in everyday life (Cole, 2004), up to 60 % of the subjects in the studies reported problems in reading colour coded charts, slides and prints. Other studies (Carter and Silverstein, 2010) describes the difficulties to distinguish and identify coloured objects in weather, financial and other maps and charts.Colour vision deficiencies are common, where congenital CVD affects about 8 % of the male population and 0.4 % of the female population. In addition, colour vision and colour perception may be affected by medical conditions or injury (acquired CVD) and situational conditions (situation induced CVD).Reviews of visual usability and accessible map design conclude that few maps appear to have been designed with CVD users in mind (Cartwright, 2015) and that the design efforts or research of accessible colours palettes for CVD observers are mostly limited to thematic maps such as choropleths (Kvitle, 2018).Daltonization methods are image processing methods to automatically enhance information in existing images. A common enhancement method is re-colouring, changing the colours in the original image to make be more distinguishable to the CVD observers. The daltonization method targets a specific type of CVD, and may also have been designed for specific applications (natural images, scientific images, information graphics etc). Therefore, the evaluation of the methods is often based on a limited set of test images. Using one specific map image as input will give very different results based on the daltonization methods.The aim of the work is primarily to examine how the colour palettes in a map are altered by different daltonization methods. Second, the aim is to explore how different map types are influenced by the daltonization methods and to propose requirements and guidelines for test images for future work. The set of test images in this work includesInformation graphics (such as a tube map).Choropleth map.Reference map based on different map providers. To illustrate the visual differences, CVD simulation methods are applied on the original images and the daltonized versions of the images.

Colour vision deficiency among students in Lagos State, Nigeria.

Congenital colour vision defects are x-linked inherited, non-progressive and untreatable disorders that describe poor colour discrimination. To determine the prevalence of congenital colour vision deficiency among students in Lagos, Nigeria. A school-based cross-sectional, cluster sample study was conducted to test the colour vision of 2326 primary and high school students. Inclusion criteria were Snellen VA 20/20 or better and absence of known ocular pathologies. Colour vision deficiency (CVD) was evaluated with the Richmond-HRR colour vision test plates. There were 1014 (43.6%) males and 1312 (56.4%) females with a mean age of 13.40 ± 2.40 years (range = 7-22 years). The prevalence of CVD was 58 (2.5%), which was higher in males 49 (4.8%) than females 9 (0.7%). The prevalence of congenital CVD was significantly associated with males (p = 0.00), but not with females (p = 0.22). Of the 58 cases of CVD, 17 (0.7%) had protan deficiency, 38 (1.6%) had deutan deficiency and three (0.1%) were unclassified. The prevalence of congenital CVD among students in Lagos is comparable to findings in other parts of Nigeria but differs from other parts of the country. These results strengthen the need to establish school vision screening.

Behavioural and emotional issues among primary school pupils with congenital colour vision deficiency in the Federal Territory of Kuala Lumpur, Malaysia: A case-control study

Background: Congenital colour vision deficiency (CCVD) is an untreatable disorder which has lifelong consequences. Increasing use of colours in schools has raised concern for pupils with CCVD. This case-control study was conducted to compare behavioural and emotional issues among age, gender and class-matched pupils with CCVD and normal colour vision (NCV). Methods: A total of 1732 pupils from 10 primary schools in the Federal Territory of Kuala Lumpur were screened, of which 46 pupils (45 males and 1 female) had CCVD. Mothers of male pupils with CCVD (n=44) and NCV (n=44) who gave consent were recruited to complete a self-administered parent report form, Child Behaviour Checklist for Ages 4-18 (CBCL/ 4-18) used to access behavioural and emotional problems. The CBCL/ 4-18 has three broad groupings: Internalising, Externalising and Total Behaviour Problems. Internalising Problems combines the Withdrawn, Somatic Complaints and Anxiety/ Depression sub constructs, while Externalising Problems combines the Delinquent and Aggressive Behaviour sub constructs. Results: Results from CBCL/ 4-18 showed that all pupils from both groups had scores within the normal range for all constructs. However, results from the statistical analysis for comparison, Mann-Whitney U test, showed that pupils with CCVD scored significantly higher for Externalising Problems (U=697.50, p=0.02) and Total Behaviour Problems (U=647.00, p= 0.01). Significantly higher scores were observed in Withdrawn (U=714.00, p=0.02), Thought Problems (U=438.50, p<0.001) and Aggressive Behaviour (U=738.00, p=0.04). Odds ratios, 95% CI, showed significant relative risk for high Total Behaviour Problem (OR:2.39 ,CI:1.0-5.7), Externalising Problems (OR:2.32, CI:1.0-5.5), Withdrawn (OR:2.67, CI:1.1-6.5), Thought Problems (OR:9.64, CI:3.6-26.1) and Aggressive Behaviour (OR:10.26, CI:3.4-31.0) scores among pupils with CCVD. Conclusion: Higher scores among CCVD pupils indicates that they present more behavioural and emotional problems compared to NCV pupils. Therefore, school vision screenings in Malaysia should also include colour vision to assist in the early clinical management of CCVD children.

Review of the main colour vision clinical assessment tests

Abstract Introduction Congenital colour vision deficiencies affect 8% of the male and 0.5% of the female population. The study of colour vision is a complex process due to several factors: the psychophysics of vision itself, the difficulty to establish mathematical models for its analysis, the vague correlation of results between different tests, and the influence of external factors such as lighting, the tests condition, or the experience of the examiner and the patient. In the present document, a simplified review was carried out on the main colour vision tests available in clinical practice. Material and methods Once a filtered preliminary review was made of the bibliography related to the study of colour vision using the PubMed search tool, the most used tests in clinical practice were selected according to their frequency of use and the purpose for which they were applied. A bibliographic study was then carried out on each particular test according to the design of the shown stimuli, its target population, and its sensitivity and specificity. Results From the 95 publications found using the PubMed search tool, in 41 of them, colour tests were used by researchers in their methodology. From the 64 colour tests used, 19 of them were different (with 4 of them being different tests adapted by research groups, and 2 of them carried out online). The most used tests were the following: Ishihara test (10.88%), Farnsworth–Munsell (7.04%), Farnsworth–Munsell 100 Hue (6.4%), Cambridge Colour Test (3.84%), Hardy–Rand–Rittler (3.2%), tests developed by the groups (2.56%), the Anomaloscope (1.28%), the online tests (1.28%) and, finally, Colour Assessment and Diagnosis (0.64%), Pfluger Trident Colour Plates (0.64%), Toothguide Training Box (0.64%), Lanthony Desaturated D-15 (0.64%), City University Test (0.64%), Universal Colour Discrimination Test (0.64%), and Rabin Cone Contrast Test (0.64%). Conclusions The Anomaloscope is the “gold standard” in terms of colour vision testing, despite its incompatibility with daily clinical practice. It is fairly complex to use, difficult to understand for children, and its practice requires having the time available. Nevertheless, it is possible to reach an accurate approximation through the combination of some of the tests listed in this article. The above mentioned tests are a good alternative to determine the presence of dyschromatopsia in settings closer to daily clinical practice or in less controlled settings than a clinical study. The major drawback among the wide range of tests available for the study of colour vision is the difficulty to compare results between tests, since units of the reported data are usually different, and experience is required for its correct interpretation. Currently, there is no consensus on which colour test is the most complete. It is, therefore, advisable to use at least 2 tests in order to ensure diagnoses, and have more extensive information about the visual perception of patients.

Depth perception in patients with congenital color vision deficiency.

To assess the effect of type and severity of congenital color vision deficiency (CCVD) on depth perception. Thirty-one male patients with a known diagnosis of CCVD were included in the study group and 31 age-matched healthy subjects in the control group. After standard ophthalmological examination including best corrected visual acuity (BCVA) testing with Snellen chart, slit-lamp examination, non-contact tonometry, and fundus examination, all patients underwent color perception testing with Hardy-Rand-Rittler (HRR) 4th edition pseudoisochromatic test plates and stereoacuity testing with Titmus stereo test plates. Of the 31 patients with CCVD, 7 were protanope and 24 were deuteranope. Mean stereoacuity was 46.77 ± 11.3, 105.7 ± 69.0, and 134.1 ± 115.2 in the control, protanope, and deuteranope groups, respectively. Stereoacuity was significantly better in the control group than in the protanope and deuteranope groups (p = 0.039, p < 0.001 respectively). No significant difference was observed between protanopes and deuteranopes regarding stereoacuity (p = 0.73). Mean BCVA was -0.01 ± 0.03, -0.02 ± 0.07, and -0.10 ± 0.11 in the control, protanope, and deuteranope groups, respectively. Mean BCVA in deuteranopes was significantly better than the control group (p = 0.004), while mean BCVA in deuteranopes and protanopes did not differ significantly (p = 0.056). No significant difference was observed between the control group and protanopes regarding visual acuity (p = 0.921). Our study showed that color vision had an important effect on depth perception and CCVD may cause decreased stereoacuity.

Behavioural and emotional issues among primary school pupils with congenital colour vision deficiency in the Federal Territory of Kuala Lumpur, Malaysia: A case-control study.

Background: Congenital colour vision deficiency (CCVD) is an untreatable disorder which has lifelong consequences. Increasing use of colours in schools has raised concern for pupils with CCVD. This case-control study was conducted to compare behavioural and emotional issues among age, gender and class-matched pupils with CCVD and normal colour vision (NCV). Methods: A total of 1732 pupils from 10 primary schools in the Federal Territory of Kuala Lumpur were screened, of which 46 pupils (45 males and 1 female) had CCVD. Mothers of male pupils with CCVD (n=44) and NCV (n=44) who gave consent were recruited to complete a self-administered parent report form, Child Behaviour Checklist for Ages 4-18 (CBCL/ 4-18) used to access behavioural and emotional problems. The CBCL/ 4-18 has three broad groupings: Internalising, Externalising and Total Behaviour Problems. Internalising Problems combines the Withdrawn, Somatic Complaints and Anxiety/ Depression sub constructs, while Externalising Problems combines the Delinquent and Aggressive Behaviour sub constructs. Results: Results from CBCL/ 4-18 showed that all pupils from both groups had scores within the normal range for all constructs. However, results from the statistical analysis for comparison, Mann-Whitney U test, showed that pupils with CCVD scored significantly higher for Externalising Problems (U=697.50, p=0.02) and Total Behaviour Problems (U=647.00, p= 0.01). Significantly higher scores were observed in Withdrawn (U=714.00, p=0.02), Thought Problems (U=438.50, p<0.001) and Aggressive Behaviour (U=738.00, p=0.04). Odds ratios, 95% CI, showed significant relative risk for high Total Behaviour Problem (OR:2.39 ,CI:1.0-5.7), Externalising Problems (OR:2.32, CI:1.0-5.5), Withdrawn (OR:2.67, CI:1.1-6.5), Thought Problems (OR:9.64, CI:3.6-26.1) and Aggressive Behaviour (OR:10.26, CI:3.4-31.0) scores among pupils with CCVD. Conclusion: Higher scores among CCVD pupils indicates that they present more behavioural and emotional problems compared to NCV pupils. Therefore, school vision screenings in Malaysia should also include colour vision to assist in the early clinical management of CCVD children.

Color Vision in Aniridia.

PurposeTo assess color vision and its association with retinal structure in persons with congenital aniridia.MethodsWe included 36 persons with congenital aniridia (10–66 years), and 52 healthy, normal trichromatic controls (10–74 years) in the study. Color vision was assessed with Hardy-Rand-Rittler (HRR) pseudo-isochromatic plates (4th ed., 2002); Cambridge Color Test and a low-vision version of the Color Assessment and Diagnosis test (CAD-LV). Cone-opsin genes were analyzed to confirm normal versus congenital color vision deficiencies. Visual acuity and ocular media opacities were assessed. The central 30° of both eyes were imaged with the Heidelberg Spectralis OCT2 to grade the severity of foveal hypoplasia (FH, normal to complete: 0–4).ResultsFive participants with aniridia had cone opsin genes conferring deutan color vision deficiency and were excluded from further analysis. Of the 31 with aniridia and normal opsin genes, 11 made two or more red-green (RG) errors on HRR, four of whom also made yellow-blue (YB) errors; one made YB errors only. A total of 19 participants had higher CAD-LV RG thresholds, of which eight also had higher CAD-LV YB thresholds, than normal controls. In aniridia, the thresholds were higher along the RG than the YB axis, and those with a complete FH had significantly higher RG thresholds than those with mild FH (P = 0.038). Additional increase in YB threshold was associated with secondary ocular pathology.ConclusionsArrested foveal formation and associated alterations in retinal processing are likely to be the primary reason for impaired red-green color vision in aniridia.

Contrast sensitivity of patients with congenital color vision deficiency.

To investigate the static and dynamic contrast sensitivity (CS) of patients with congenital red-green color vision deficiency (CVD) and to compare these values with those of healthy control subjects. The study included 25 subjects with congenital CVD (10 with strong protan defect and 15 with strong deutan defect) and 20 age- and gender-matched healthy subjects. Following detailed ophthalmological examination, monocular static and dynamic CS measurements were taken with the Monpack3 device (Metrovision, Perenchies, France) on all subjects. The data from the right eyes of all the subjects were used for statistical analysis. The mean age of the groups was similar (deutan group: 25.3 ± 11.3years, protan group: 27.1 ± 12.2years, control group: 26.7 ± 8.8years, p = 0.98). The mean static and dynamic CS values in the protan and deutan groups were higher compared to those of the healthy control subjects, but not at a statistically significant level (all p > 0.017). The static and dynamic CS values of patients with congenital red-green CVD were similar to those of healthy control subjects.

Konjenital Renk Görme Bozukluğunun Hardy-Rand-Rittler Psödoizokromatik Testi ile Tespiti

Objective: To screen, categorize and grade the severity of congenital color vision deficiency (CVD) by using Hardy-Rand-Rittler (HRR) pseudoisochromatic test plates and to detect the state of awareness of people about their abnormal color vision. Material and Methods: 2211 consecutive subjects aged between 15-45 years were recruited for the study. All patients underwent a color vision test by using HRR 4th edition pseudoisochromatic test plates. Both eyes were tested separately and the data of the right eyes were used for statistical analysis. The patients detected to have CVD were also asked if they were previously aware of their abnormal color vision. Results: Abnormal color vision was encountered in 59 out of 993 males (5.9%) and 4 out of 1218 females (0.3%). Congenital CVD cases were deutan in 47 (74.6%), protan in 11 (17.5%) and unclassified in 5 (7.9%) subjects. Five (7.9%) of the CVD subjects were classified as having mild, 21 (33.4%) having medium and 37 (58.7%) having strong color deficiency. Nineteen subjects (30.2%) were previously unaware of their abnormal color vision. The awareness of abnormal color vision was significantly associated with male gender and increased severity of the disease. Conclusion: HRR test may be used to detect, classify and grade severity of CVD. Approximately one third of the patients with CVD were previously unaware of their abnormal color vision. Female subjects and patients with mild CVD were more frequently unaware of their color vision problem.

Prevalence of Congenital Colour Vision Deficiency (CVD) in School Children of Bhaktapur, Nepal

Background: The incidence of congenital colour vision deficiency shows different trends and may vary in different geographical areas. Colour plays vital role in daily life functioning but there is no effective screening for Colour Vision Deficiency (CVD) at any school level. The school children with CVD may feel difficulty in identifying colour figures, lab instruments and specimens which may lead to failure in the examination. Not only this they may find difficulty in daily life functioning so, this study is aimed to find out the incidence of CVD in school children. Methods: A total of 585 school children including 312 males and 273 females between ages 10-16 years were examined for congenital CVD in different schools of Bhaktapur. Each school child was shown the complete range of Ishihara’s plates under day light conditions at distance of 75 cm and each plate was shown to them for duration of 5 seconds. Results: Children’s colour vision was tested using Ishihara’s 38 Plates edition. Among 312 boys, 16(5.12%) were colour deficient. Among 273 girls, 7(2.56%) were colour deficient. Conclusion: With this incidence of colour vision deficiency it shows the importance of screening for CVD in school children and counseling them for daily life functioning and making aware about the choice of career in future.

Prevalence of Congenital Colour Vision Deficiency in Nigerians Living in Ugep, Cross River State

Prevalence of Congenital Colour Vision Deficiency in Nigerians Living in Ugep, Cross River State

Congenital and acquired colour vision deficiency among population in North Kordofan State of Sudan

Background: Congenital colour vision deficiency (CVD) is an x-linked chromosome disorders which, predominantly occurring in males. This disorder results from abnormalities in one or all three-cone type's photoreceptors. It is mainly affect long wavelength photopigments (red) and middle wavelength photopigments (green). However, the acquired CVD is due to ocular or general pathology as well as due to prolonged use of some medications, which is mostly affect short wavelength photopigments (blue). Objective: This study aimed to evaluate the prevalence of hereditary and acquired CVDs among Sudanese population in North Kordofan State. Materials and Methods: This is a population-based crossed-sectional study of 1100 subjects, their age ranged from 10 to 80 years, the mean age of subjects was 40.4 ± 16.6 (standard deviation) were selected from three districts and 110 subjects were selected from each set. Investigations included visual acuity using Snellen tumbling E-chart, refraction using retinoscopy, colour vision using Ishihara and City University colour vision tests, external eye using torch and magnifier and evaluation of internal eye and ocular media using direct ophthalmoscope. Results: A total of 1216 subjects were invited to participate in the study and 1100 were examined resulting in a participation rate of 91%. The findings revealed that 61 (5.5%) had CVD, 49 (9.0%) were males and 12 (2.2%) were females. The prevalence of congenital (red-green) CVD was 39 (3.5%) which was high in males 37 (6.8%) than females 2 (0.4%). The prevalence of congenital CVD was found associated with males (P

Congenital Color Vision Deficiency (CVD) in Children Living in High Altitudes of Nepal

Background: It has shown that congenital color vision deficiency (CVD) has different prevalence and patterns in various ethnic groups and geographical areas. Perception of color have significant role in routine daily life. The children with color vision defects may have problems in detecting colors in schools, color posters and slides which may lead to failure in exam as well as in the daily learning activities. So, this present study is aimed to find out the prevalence of CVD in children living in high altitudes of Nepal.Methods: A total of 423 children including 217 males and 206 females between ages 11-15 years were examined for congenital CVD in children of high altitudes (2500meter above sea-level) of Sindhupalchowk and Dolakha districts of Nepal. Each subject was shown the plates of Ishihara for color vision under normal day light at distance of 75 cm and the duration given for them to see was 5 seconds.Results: Children’s color vision was tested using Ishihara’s 38 Plates edition. Among 217 boys, 24 (11.05%) were color deficient. Among 206 girls, 5 (2.42%) were color deficient.Conclusion: The trends of color vision deficiency in high altitudes showed the need of more and more research on CVD in children and make them aware about the problem that might be faced by them in near future.

Historical Development of the Wool and Colour Plate Tests for Screening for Colour Vision Deficiencies in German Speaking Countries

Colour vision is a complex visual function that can be affected by congenital and/or acquired disorders. The frequency of congenital colour vision deficiencies has been investigated in rail and navy staff since the 1870s. Various test methods have been developed. Wool tests, flor contrast tests and colour plate tests have been used. A published colour plate test, based on Stilling's pseudo-isochromatic plates in combination with a flor contrast test, has been a common screening method for colour vision testing in German-speaking countries. This test is intended to detect congenital and acquired colour vision deficiencies in a simple and safe manner. More modern options, such as Internet and tablet PC have technical limitations, but will increasingly be used for screening for colour vision deficiencies.

Editorial: Color Vision Sensation and Perception.

Color vision is one of the most intriguing phenomena of the visual experience and has been the object of study from vision scientists to philosophers of perception. The wavelengths, their intensity and purity are experienced as hue, brightness and saturation based on complex information processing of the light entering the eyes. This special research topic is devoted to covering from basic aspects based on light and retinal processes to perceptual and cognitive mechanisms and their respective applications in clinical settings. The reader will find a series of papers organized in two chapters, one devoted to the more basic phenomena and processing, the other focused on the more cognitive and cultural aspects. The integrative aspect of luminance in color vision starts our journey. Reduction in number of levels of luminance in pseudoisochromatic stimulations affects the chromaticity thresholds measured psychophysically, suggesting interactions between luminance and color in those stimuli with luminance steps lower than seven (Souza et al.). Color sensation was also investigated under low-light levels. Mesopic and scotopic conditions could be considered an interference zone for color vision since rods activities generate physiological interferences in cone-driven retinal chromatic pathways. This review paper keeps us up to date regarding the range and impact of rod–cone interactions on human visual function and performance (Zele and Cao). Clinical applications centered on congenital color blindness end the first chapter. Sensory psychophysical thresholds on the tritanopic color confusion axis were investigated in protanomalous and deuteranomalous subjects (Costa et al.). Reduction in discrimination was found for both types of congenital color blindness, protanomalous and deuteranomalous, but subjects in the latter group showed worse results. Electrophysiological assessments regarding luminance and compound stimuli (luminance plus red-green stimulus) were also evaluated in congenital color blindness subjects. Since compound stimuli elicited small or no response in red-green congenital color blinds, this finding could indicate that the cortical response for compound stimuli in the present experiment was dominated by chromatic contribution (Risuenho et al.). A search for discrimination thresholds addressed using the pseudoisochromatic plates configures a new psychophysical application for the traditional and widely used color test (Jurasevska et al.). Basic perceptual phenomena of Gestalt theories regarding color vision were addressed using figure-ground perception on saturation and contrast polarity modulations. The study conducted by Dresp-Langley and Reeves investigated the lightness dependency of the achromatic loci in color space. The results pointed toward a hitherto undocumented functional role of color saturation in the genesis of form, and in particular figure-ground percepts. Two experiments conducted by Kuriki showed that first, a color-appearance space normalized to daylight may be defined for the human visual system and second, that color space could reduce the discrepancy between the achromatic loci and the lightness axis of the color appearance models. The last study of the perceptual mechanism section relates retinal image quality for the display red and blue pixel radiation with the chromostereopsis retinal disparity achieved (zolinsh and Muizniece). Color is also important from an anthropological view in which a long debate regarding the existence of natural categories of hue and their universality has been addressed by ethological, electrophysiological, behavioral and psychophysical perspectives. The color naming and gender section presents contributions regarding the variations in color naming occurring in congenital color blindness subjects and the gender and cultural aspects related to color preferences. The study of Nagy et al. shows that dichromatic subjects involve the brightness properties of the different spectral stimuli when judging their chromatic content and that at the shorter wavelengths the signal of the intact tritos photoreceptor dominates the decision making in color naming tasks, even for the anopes. Al-Rasheed provides evidence that both sex differences and cultural differences are relevant in hue preference in terms of how stimulus-background cone-contrast was weighted summarizing color preference quantitatively rather than using subjective color names. The question of how we see colors and how we can discuss their impact in many dimensions of our life is an actual and multidiscipline inquiry to which we hope to contribute with this special research topic. Enjoy this special topic on color vision.

Psychophysical Evaluation of Congenital Colour Vision Deficiency: Discrimination between Protans and Deutans Using Mollon-Reffin's Ellipses and the Farnsworth-Munsell 100-Hue Test.

We have used the Farnsworth-Munsell 100-hue (FM 100) test and Mollon-Reffin (MR) test to evaluate the colour vision of 93 subjects, 30.4 ± 9.7 years old, who had red-green congenital colour vision deficiencies. All subjects lived in Belém (State of Pará, Brazil) and were selected by the State of Pará Traffic Department. Selection criteria comprised the absence of visual dysfunctions other than Daltonism and no history of systemic diseases that could impair the visual system performance. Results from colour vision deficient were compared with those from 127 normal trichromats, 29.3 ± 10.3 years old. For the MR test, measurements were taken around five points of the CIE 1976 colour space, along 20 directions irradiating from each point, in order to determine with high-resolution the corresponding colour discrimination ellipses (MacAdam ellipses). Three parameters were used to compare results obtained from different subjects: diameter of circle with same ellipse area, ratio between ellipse’s long and short axes, and ellipse long axis angle. For the FM 100 test, the parameters were: logarithm of the total number of mistakes and positions of mistakes in the FM diagram. Data were also simultaneously analysed in two or three dimensions as well as by using multidimensional cluster analysis. For the MR test, Mollon-Reffin Ellipse #3 (u’ = 0.225, v’ = 0.415) discriminated more efficiently than the other four ellipses between protans and deutans once it provided larger angular difference in the colour space between protan and deutan confusion lines. The MR test was more sensitive than the FM 100 test. It separated individuals by dysfunctional groups with greater precision, provided a more sophisticated quantitative analysis, and its use is appropriate for a more refined evaluation of different phenotypes of red-green colour vision deficiencies.

Reduced Discrimination in the Tritanopic Confusion Line for Congenital Color Deficiency Adults.

In congenital color blindness the red–green discrimination is impaired resulting in an increased confusion between those colors with yellow. Our post-receptoral physiological mechanisms are organized in two pathways for color perception, a red–green (protanopic and deuteranopic) and a blue–yellow (tritanopic). We argue that the discrimination losses in the yellow area in congenital color vision deficiency subjects could generate a subtle loss of discriminability in the tritanopic channel considering discrepancies with yellow perception. We measured color discrimination thresholds for blue and yellow of tritanopic channel in congenital color deficiency subjects. Chromaticity thresholds were measured around a white background (0.1977 u′, 0.4689 v′ in the CIE 1976) consisting of a blue–white and white–yellow thresholds in a tritanopic color confusion line of 21 congenital colorblindness subjects (mean age = 27.7; SD = 5.6 years; 14 deuteranomalous and 7 protanomalous) and of 82 (mean age = 25.1; SD = 3.7 years) normal color vision subjects. Significant increase in the whole tritanopic axis was found for both deuteranomalous and protanomalous subjects compared to controls for the blue–white (F2,100 = 18.80; p < 0.0001) and white–yellow (F2,100 = 22.10; p < 0.0001) thresholds. A Principal Component Analysis (PCA) found a weighting toward to the yellow thresholds induced by deuteranomalous subjects. In conclusion, the discrimination in the tritanopic color confusion axis is significantly reduced in congenital color vision deficiency compared to normal subjects. Since yellow discrimination was impaired the balance of the blue–yellow channels is impaired justifying the increased thresholds found for blue–white discrimination. The weighting toward the yellow region of the color space with the deuteranomalous contributing to that perceptual distortion is discussed in terms of physiological mechanisms.

Familial Muller cell sheen dystrophy associated with congenital color vision deficiency

Familial Muller cell sheen dystrophy associated with congenital color vision deficiency