Congenital Color Deficiency Research Articles

Effects of color-enhancing glasses on color vision in congenital red-green color deficiencies.

As commercially available glasses for color vision deficiency (CVD) are classified as low risk, they are not subject to stringent marketing regulations. We investigate how EnChroma and VINO glasses affect performance on the Colour Assessment and Diagnosis (CAD) test in individuals with CVD. Data were obtained from 51 individuals with red-green CVD. Blood or saliva samples were collected to examine the structure of the OPN1LW/OPN1MW array. Individuals completed the CAD test twice without glasses and once with each pair of glasses. Although there was a statistically significant effect of both glasses, only that of VINO could be considered functionally meaningful.

Color Compensation in Anomalous Trichromats Assessed with fMRI

Anomalous trichromacy is a common form of congenital color deficiency resulting from a genetic alteration in the photopigments of the eye's light receptors. The changes reduce sensitivity to reddish and greenish hues, yet previous work suggests that these observers may experience the world to be more colorful than their altered receptor sensitivities would predict, potentially indicating an amplification of post-receptoral signals. However, past evidence suggesting such a gain adjustment rests on subjective measures of color appearance or salience. We directly tested for neural amplification by using fMRI to measure cortical responses in color-anomalous and normal control observers. Color contrast response functions were measured in two experiments with different tasks to control for attentional factors. Both experiments showed a predictable reduction in chromatic responses for anomalous trichromats in primary visual cortex. However, in later areas V2v and V3v, chromatic responses in the two groups were indistinguishable. Our results provide direct evidence for neural plasticity that compensates for the deficiency in the initial receptor color signals and suggest that the site of this compensation is in early visual cortex.

THE EFFECT OF EYE DOMINANCE IN COLOR PERCEPTION AMONG DENTAL STUDENTS WITH NORMAL COLOR VISION

Introduction: Various factors were reported to be responsible for influencing color perception during shade matching. These factors include lighting conditions and viewer's physiological variables. There is limited information regarding the effect of eye dominance in color perception in the dental literature. Objectives: To evaluate the effect of eye dominance on color perception among dental students in Alexandria University with normal color vision using Farnsworth- Munsell 100- hue test and the corresponding software. Materials and Methods: One hundred undergraduate dental students without congenital color deficiency were evaluated using Ishihara plates upon their voluntary participation. Out of these 100 participants, 43 were males and 57 were females. The dominant eye of each participant was determined using Miles test. Color perception evaluation was examined using Farnsworth – Munsell 100 hue test (FM 100 hue test). The data were tabulated and statistically analyzed using the Wilcoxon signed-rank test (α=0.05). Results: Statistical tests showed significant difference between the dominant eye and non-dominant eye in male participants (P=.031) and no significant difference between the dominant eye and non-dominant eye in female participants (P=.691). Conclusions: The dominance of the eye had a significant effect on the color perception in male participants. Keywords: Color matching, eye dominance, FM 100 hue test. Running title: The effect of eye dominance on color perception.

Analysis of Hue Circle Perception of Congenital Red-green Congenital Color Deficiencies Based on Color Vision Model

To investigate individual property of internal color representation of congenital red-green color-deficient observers (CDOs) and color-normal observers (CNOs) precisely, difference scaling experiment using pairs of primary colors was carried out for protans, deutans, and normal trichromats, and the results were analyzed using multi-dimensional Scaling (MDS). MDS configuration of CNOs showed circular shape similar to hue circle, whereas that of CNO showed large individual differences from circular to U- shape. Distortion index, DI, is proposed to express the shape variation of MDS configuration. All color chips were plotted in the color vision space, (L, r/g, y/b), and the MDS using a non-linear conversion from the distance in the color vision space to perceptual difference scaling was successful to obtain U-shape configuration that reflects internal color representation of CDOs.

Color image evaluation of congenital red-green color deficient and normal color vision observers

How and to what extent the increase of Cab * affects on various subjective evaluations for congenital red-green color deficiency (CVD) and normal color vision (NCV) observers was investigated using scenery, food, and graph images. Results of "Pale vs Deep" evaluation indicate similar tendency for all color vision types in all test images, indicating that CVDs recognize the saturation change of images similar to NCVs using some kind of strategy. Individual differences of the CVDs in the results of other adjective pairs such as "Unnatural vs Natural" are generally larger than those of NCVs. Some color combinations in the graph images are indiscriminable for either protan or deutan, and thus are not recommended to be used.

Evaluation of the Validity of "The Color Confusion Plates for People with Congenital Color Deficiencies"

Evaluation of the Validity of "The Color Confusion Plates for People with Congenital Color Deficiencies"

Color Functionality Used in Visual Display for Occupational and Environmental Safety and Managing Color Vision Deficiency.

The effects of color perception are utilized in visual displays for the purpose of safety in the workplace and in daily life. These effects, generally known as color functionality, are divided into four classifications: visibility, legibility, conspicuity and discriminability. This article focuses on the relationship between the color functionality of color schemes used in visual displays for occupational and environmental safety and color vision deficiency (particularly congenital red-green color deficiency), a critical issue in ophthalmology, and examines the effects of color functionality on the perception of the color red in individuals with protan defects. Due to abrupt system reforms, current Japanese clinical ophthalmology finds itself in a situation where it is insufficiently prepared to handle congenital red-green color deficiencies. Indeed, occupational problems caused by color vision deficiencies have been almost completely neglected, and are an occupational safety and health concern that will need to be solved in the future. This report will present the guidelines for the color vision testing established by the British Health and Safety Executive (HSE), a pioneering example of a model meant to solve these problems. Issues relating to the creation of guidelines adapted to Japanese clinical ophthalmology will also be examined, and we will discuss ways to utilize color functionality used in visual displays for occupational and environmental safety to help manage color vision deficiency.

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.

Processing of color signals in female carriers of color vision deficiency

The aim of this study was to assess the chromatic sensitivity of carriers of color deficiency, specifically in relation to dependence on retinal illuminance, and to reference these findings to the corresponding red-green (RG) thresholds measured in normal trichromatic males. Thirty-six carriers of congenital RG color deficiency and 26 normal trichromatic males participated in the study. The retinal illuminance was estimated by measuring the pupil diameter and the optical density of the lens and the macular pigment. Each subject's color vision was examined using the Color Assessment and Diagnosis (CAD) test, the Ishihara and American Optical pseudoisochromatic plates, and the Nagel anomaloscope. Carriers of deuteranopia (D) and deuteranomaly (DA) had higher RG thresholds than male trichromats (p < 0.05). When referenced to male trichromats, carriers of protanomaly (PA) needed 28% less color signal strength; carriers of D required ∼60% higher thresholds at mesopic light levels. Variation in the L:M ratio and hence the absolute M-cone density may be the principal factor underlying the poorer chromatic sensitivity of D carriers in the low photopic range. The increased sensitivity of PA carriers at lower light levels is consistent with the pooling of signals from the hybrid M' and the M cones and the subsequent stronger inhibition of the rods. The findings suggest that signals from hybrid photopigments may pool preferentially with the spectrally closest "normal" pigments.

Effects of hypoxia on color vision with emphasis on the mesopic range

The ability to see clear images, to resolve fine spatial detail in faint objects, to see and appreciate small color differences, to discriminate motion direction and to detect rapidly flickering lights over a very large range of natural illumination is something we often take for granted. Good vision is our expectation, but as we grow older, we become aware of very gradual visual deficits that in some cases can lead to severe loss of vision. These deficits are often caused by changes in the optics of the eye and/or the retina. A normal supply of oxygen and nutrients to the retina is essential to maintain good vision, but when the supporting mechanisms fail, local hypoxia can trigger structural changes that affect normal vision. In this article, we review endogenous and exogenous factors that cause changes in the supply of oxygen to the eye and how these can affect color vision when oxygen demands vary with light adaptation level. We review the latest color vision assessment techniques and show how the level of retinal oxygenation can affect color vision in normal trichromats and in subjects with congenital color deficiencies. We also discuss acquired loss of color vision in relation to hypoxia and how it may soon become possible to use advanced vision and optometric tests to detect the earliest signs of disease that precede clinical diagnosis and to monitor disease progression and effectiveness of treatment. We explore how knowledge of normal differences between photopic and mesopic visual performance and the expected limits of normal variability as a function of age can help achieve this goal.

Color Constancy of Red-Green Dichromats and Anomalous Trichromats

Purpose. Color-vision deficiency is associated with abnormalities in color matching and color discrimination, but its impact on the ability of people to judge the constancy of surface colors under different lights (color constancy) is less clear. This work had two aims: first, to quantify the degree of color constancy in subjects with congenital red-green color deficiency; second, to test whether the degree of color constancy in anomalous trichromats can be predicted from their Rayleigh anomaloscope matches. Methods. Color constancy of red-green color-deficient subjects was tested in a task requiring the discrimination of illuminant changes from surface-reflectance changes. Mondrian-like colored patterns, generated on the screen of a computer monitor, were used as stimuli to avoid the spatial cues provided by natural objects and scenes. Spectral reflectances were taken from the Munsell Book of Color and from natural scenes. Illuminants were taken from the daylight locus. Results. Protanopes and deuteranopes performed more poorly than normal trichromats with Munsell spectral reflectances but were less impaired with natural spectral reflectances. Protanomalous and deuteranomalous trichromats performed as well as, or almost as well as, normal trichromats, independent of the type of reflectance. Individual differences were not correlated with Rayleigh anomaloscope matches. Conclusions. Despite the evidence of clinical color-vision tests, red-green color-deficient persons are less disadvantaged than might be expected in their judgments of surface colors under different lights.

A study of unusual Rayleigh matches in deutan deficiency

Rayleigh match data were modeled with the aim of explaining the locations of match midpoints and matching ranges, both in normal trichromats and in subjects with congenital color deficiency. Model parameters included the wavelength of peak sensitivity of cone photopigments, the effective photopigment optical density, and the noise amplitude in the red-green color channel. In order to avoid the suprathreshold, perceptual effects of extreme L:M cone ratios on color vision, selective post-receptoral amplification of cone signals is needed. The associated noise is also amplified and this causes corresponding changes in red-green threshold sensitivity. We propose that the noise amplitude and hence the size of the matching range in normal trichromats relates to the known inter-subject variation in the relative numbers of L and M cones. If this hypothesis can be shown to account for the extremes of the red-green matching range measured in normal trichromats, it is of interest to establish the extent to which it also predicts the unexpected, small matching ranges that are observed in some subjects with red-green color deficiency. A subset of subjects with deutan deficiency that exhibited less common Nagel matches were selected for genetic analysis of their cone pigment genes in order to confirm the type of deficiency, and to predict the corresponding peak wavelength separation (delta lambda(max)) of their two, long-wavelength cone pigments. The Rayleigh match model predicted accurately the midpoint and the range for the spectral differences specified by the genes. The prediction also required plausible selection of effective optical density of the cone pigments and noise. The noise needed varied, but the estimates were confined to lie within the limits established from the matching ranges measured in normal trichromats. The model predicts correctly the small matching ranges measured in some deuteranomalous subjects, principally accounted for by a low estimate of noise level in the red-green channel. The model also predicts the "normal" matches made by some subjects that rely on two hybrid genes and therefore exhibit red-green thresholds outside the normal range, typical of mild deuteranomaly.

John Dalton: Though in Error, He Still Influenced Our Understanding of Congenital Color Deficiency

John Dalton was born in the 18th century and was recognized mainly for his work on the chemical atomic theory and “Dalton's Law” for the partial pressure of gases. However, during his lifetime he was already recognized for his theories on “colorblindness,” with which he was afflicted. He was perhaps the first to report personal observations from experimentation on his color vision deficiency. His theory regarding its pathogenesis was posthumously proven to be incorrect after observations performed on his enucleated eyes. Further generations later, DNA analyses by PCR conclusively recorded the specific color deficiency (deuteranopia) with which Dalton was affected.

Evaluation of the New Web-Based “Colour Assessment and Diagnosis” Test

The purpose of the study was to determine the sensitivity, specificity, and repeatability of the web-based Colour Assessment and Diagnosis (CAD) test in comparison to current tests of color vision. Thirty color normals and 30 color deficients, identified and diagnosed by the Nagel anomaloscope, were tested. The results of the CAD test were compared with standard tests like Nagel anomaloscope, Ishihara (concise version, 2001), Hardy, Rand and Rittler (HRR; 4 ed) pseudoisochromatic test, and the Farnsworth Munsell 100 (FM-100) hue test. Using the Nagel anomaloscope as the "gold standard," the sensitivity with the CAD test was 93.33%, Ishihara 96%, HRR 100%, and the FM-100 hue 100%. The specificity was 100% with CAD and the Ishihara color plates, whereas it was 33% with the HRR and 83% with the FM-100 hue test. The concurrent validity of the CAD test for color normals was 93.75%. The concurrent validity of CAD test for color deficiency was 100%. Thus, anyone failing the CAD test has a color defect. The coefficient of agreement for the Nagel anomaloscope and the CAD test was 0.93, with Ishihara it was 0.96, with the HRR it was 0.33, and with FM-100 hue it was 0.83. These results showed that the CAD test is a valid test for identifying congenital red-green color deficiency. Further testing is required in a larger population of anomalous trichromats.

New Color Vision Tests to Evaluate Faulty Color Recognition

Purpose: To develop and assess new color vision tests to be used in evaluating faulty color recognition. Methods: We developed new color vision tests to evaluate faulty color recognition. The two types of color vision tests, designed to assess faulty color recognition in color vision deficiencies, are based on principles that are different from those of the conventional color vision tests. In the first test plate, the subject is asked to choose either a red, green, or gray line from among 10 lines that are randomly colored red, green, gray, yellow, or blue. The score is the difference between the number of correct answers and the number of incorrect answers. In the second test plate, the subject is asked to identify a total of 10 red azalea blossoms, which are dispersed among numerous green leaves. Seventy-five persons with congenital color deficiencies and 20 subjects with normal color vision were examined using these new test plates. Results: The scores differed significantly between dichromats and anomalous trichromats, and between anomalous trichromats and subjects with normal color vision. Conclusions: The new tests are easy to use, sensitive, and have good reproducibility for use in discriminating subjects with color vision anomalies. These tests reveal the faulty color recognition that occurs unconsciously in persons with color deficiencies, and are useful in judging the quantification of color vision required in their daily life and occupations.

Prevalence of congenital color deficiencies in secondary-school students in Tehran.

A population-based study was conducted to determine the prevalence of color deficiencies in secondary-school students (ages 12-14) in Tehran. A total of 2,058 students (1,136 males, 922 females) were examined with Ishihara pseudoisochromatic color plates. In the study population, 97 cases of defective color vision were detected, including 93 males and 4 females. The affected individuals all had negative histories of previous systemic and ocular disease or chronic use of medications. The visual acuity was 20/20 and the fundus was normal in all affected students. Of the 93 cases of defective color vision in males (8.18%), 56 cases (4.93%) involved deuteranomaly, 13 (1.14%) protanomaly, 13 (1.14%) deuteranopia, and 11 (0.97%) protanopia. The four cases in females (0.43%) involved deuteranomaly in three cases (0.32%) and protanomaly in 1 case (0.11%). Deuteranopia and protanopia were not detected in females. This is the first study to determine the prevalence of congenital color blindness in Iran. The results agree with reports of prevalence of congenital color blindness from Western Europe.

The incidence of congenital color deficiency among Koreans.

It is important to investigate the incidence of congenital color deficiency and to determine the type and degree because the color deficiency can effect as a handicap to certain occupations. The incidence of congenital color deficiency is remarkably constant among Caucasians but other races show considerable variations. We investigated the incidence of congenital color deficiency among Koreans by the use of H-R-R pseudoisochromatic plates. The present study revealed that the incidence of congenital color deficiency among Koreans was 31.5% (5.90% in men, 0.44% in women).

Electrophysiological study of the pigmentfarbenamblyopie.

The spectral sensitivity of the rapid off-response in the electroretinogram is found to be abnormal in some cases of Pigmentfarbenamblyopie or congenital red-green color deficiency. We hypothesize that there exists a fragile cone mechanism in these cases which show an abnormality in spectral sensitivity of the rapid off-response.

Electroretinographic off-response in congenital red-green color deficiency and its genetic carrier.

The spectral sensitivity of the rapid off-response in the electroretinogram is found to be abnormal in all protans and deutans so far tested, and in some of their genetic carriers. The rapid off-response is an objective means of assessing the x-linked recessive color deficiencies and their carrier state.

PHYSIOLOGIC AND CLINICAL OPTHALMOLOGIC PROBLEMS IN RELATION TO INDIVIDUAL VARIABILITY

CONGENITAL COLOR DEFICIENCIES In a minority of persons the form of color vision hitherto discussed, with the exception of a few individual variations which do not detract from its general character, is not applicable. These are the so-called color defectives—of whom, as modern investigations show, several types are distinguishable. The majority of recent authors agree that besides the true partly color blind, who do not perceive certain definite colors, e. g., red and green, there are persons who are able to perceive all color qualities but whose color sense is, nevertheless, different from that of the normal person. These are called anomalous. Concerning the vision of the congenitally color blind: It is generally accepted that it is impossible to conclude from the fact that they correctly name the colors of certain objects that they experience the same color sensations as do normal persons. The color blind have from childhood