Deutan Deficiency Research Articles

Prevalence of Color Vision Deficiency in an Adult Population in South Korea.

Large differences in failure rates for color vision screening have been reported among different regional groups. However, color vision deficiency prevalence in Korea has only been investigated within a small area of the country. This study examines the prevalence of failing a color vision screening and its sex-related differences using a sample that is representative of the whole Korean population. This population-based cross-sectional study evaluated 2686 subjects (age, 19 to 49 years) who participated in the sixth Korea National Health and Nutrition Examination Survey (2013). Color vision deficiency was assessed using the Hardy-Rand-Rittler (HRR) test by an ophthalmologist. According to standard criteria for the HRR, it classified each subject as color normal, protan, deutan, tritan, or unclassified color vision loss. All participants had comprehensive medical evaluations and ocular history taken. The weighted overall prevalence of color vision deficiency in the Korean population was 3.9% (95% confidence interval, 3.0 to 5.4%). The prevalence of color vision deficiency was higher in male participants (6.5%) than in female participants (1.1%). Among all participants, deutan deficiency (2.5%) had a higher prevalence than did protan deficiency (0.4%). For male participants who failed the HRR screening, deutan-type deficiency was detected most often (64.2%), whereas an unclassified color vision deficiency type was the most common (52.9%) among female participants who failed the HRR screening. As expected, male participants were more likely to fail the HRR screening compared with female participants (prevalence ratio, 6.08; 95% confidence interval, 3.61 to 10.26). This large population-based study of color vision deficiency among Koreans gives the most accurate estimate of failing a color vision screening test to date and provides useful information for planning adaptive strategies.

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.

Perception of color emotions for single colors in red-green defective observers.

It is estimated that inherited red-green color deficiency, which involves both the protan and deutan deficiency types, is common in men. For red-green defective observers, some reddish colors appear desaturated and brownish, unlike those seen by normal observers. Despite its prevalence, few studies have investigated the effects that red-green color deficiency has on the psychological properties of colors (color emotions). The current study investigated the influence of red-green color deficiency on the following six color emotions: cleanliness, freshness, hardness, preference, warmth, and weight. Specifically, this study aimed to: (1) reveal differences between normal and red-green defective observers in rating patterns of six color emotions; (2) examine differences in color emotions related to the three cardinal channels in human color vision; and (3) explore relationships between color emotions and color naming behavior. Thirteen men and 10 women with normal vision and 13 men who were red-green defective performed both a color naming task and an emotion rating task with 32 colors from the Berkeley Color Project (BCP). Results revealed noticeable differences in the cleanliness and hardness ratings between the normal vision observers, particularly in women, and red-green defective observers, which appeared mainly for colors in the orange to cyan range, and in the preference and warmth ratings for colors with cyan and purple hues. Similarly, naming errors also mainly occurred in the cyan colors. A regression analysis that included the three cone-contrasts (i.e., red-green, blue-yellow, and luminance) as predictors significantly accounted for variability in color emotion ratings for the red-green defective observers as much as the normal individuals. Expressly, for warmth ratings, the weight of the red-green opponent channel was significantly lower in color defective observers than in normal participants. In addition, the analyses for individual warmth ratings in the red-green defective group revealed that luminance cone-contrast was a significant predictor in most red-green-defective individuals. Together, these results suggest that red-green defective observers tend to rely on the blue-yellow channel and luminance to compensate for the weak sensitivity of long- and medium-wavelength (L-M) cone-contrasts, when rating color warmth.

Prevalence of colour blindness in province of Vojvodina - Republic of Serbia

The absence of one or more receptor types in the eye leads to colour blindness. The frequency of this anomaly varies between populations but also within different regions of a country. The aim of the study is to determine the frequency of colour blindness in the region of Vojvodina-Republic of Serbia. The study includes data obtained in the investigations conducted during the period 1996-2009. The total number of subjects is 14125 (6847 males; 7278 females). The Ishihara plates are applied as a common methodological procedure. In total, the frequency of colour-blind males and females is 5.62% and 0.34%, respectively. As for a particular type of this deficiency, the results suggest that deutan deficiency prevails in relation to protan. Prevalence of colour blindness in all three regions of Vojvodina is very similar. The genetic heterogeneity of ethnic groups for this anomaly is relatively small. In comparison with earlier studies conducted in the region of Vojvodina, a slightly lower prevalence of daltonism is observed in the present population. The obtained results are within the limits set for European populations.

Multispectral analysis and cone signal modelling of pseudoisochromatic test plates

The aim of the study is to determine the consistency of the desired colour reproduction of the stimuli using calibrated printing technology available to anyone (EpsonStylus Pro 7800 printer was). 24 colour vision assessment plates created in the University of Latvia were analysed right after their fabrication on august 2012 and after intense use for 7 months (colour vision screening on 700 people). Multispectral imagery results indicate that the alignment of the samples after seven months of use has maintained on the CIExy confusion lines of deutan deficiency type, but the shift towards achromatic area in the diagram indicate decrease in the total colour difference (ΔE*ab) of test background (achromatic) areas and stimuli (chromatic) areas, thus affecting the testing outcome and deficiency severity level classification ability of the plates.

Analysis of introns and promoters of L/M visual pigment genes in relation to deutan color-vision deficiency with an array of normal gene orders

Among the 447 Japanese men with deutan color-vision deficiency that we analyzed, 61 had a normal order array of L/M pigment genes. Three of the 61 men had an exonic mutation, but the other 58 had no mutations even in the flanking introns of their M genes. In these 58 men, 55 had a -71A --> C substitution in the M gene. Two hypotheses were built up for the substitution: it is in linkage disequilibrium with a genuine cause of deficiency in the introns, or itself is the cause of the deficiency. For the first hypothesis, we sequenced entire regions of both the L and M genes in 30 color-normal Japanese men who had one each of the L and M genes to understand normal variations of the introns. Fifty-two already known and 15 newly identified polymorphic sites could be classified into three categories: those with no polymorphisms in the Japanese group, those essentially different between the L and the M genes, and the others. We then sequenced the entire region of the M genes in 12 representative deutan individuals with a normal gene-order array but found no significant mutations. For the second hypothesis, we performed a reporter assay and found that the M gene promoter with -71C had a 60-70% reduction in activity when compared to that with -71A. These results suggest that the -71A --> C substitution is not in linkage disequilibrium with an intronic mutation, but the substitution itself may affect the transcription of the M gene, leading to deutan deficiency.

What limits chromatic sensitivity in normal and colour deficient observers?

Abstract Purpose Variability in chromatic sensitivity was assessed in normal trichromats (n=133) and in subjects with deutan (n= 106) and protan (n=48) deficiency. The purpose of this study was to quantify variability within normal colour vision and to determine how this impacts the assessment of minimum colour vision requirements within occupational environments. Methods Rayleigh matches were modelled with the aim of explaining the locations of match midpoints and ranges. Model parameters included the wavelength of peak sensitivity of cone photopigments, the photopigment optical density and the noise amplitude in the red/green colour channel. In order to avoid the suprathreshold, perceptual effects of extreme L:M cone ratios on colour vision, selective postreceptoral amplification of cone signals is needed. The noise is also amplified and this causes corresponding changes in red/green threshold sensitivity. Results We measured midpoint and matching range in anomaloscope matches and red/green and yellow/blue thresholds under conditions that isolate the use of colour signals. A subset of subjects with deutan deficiency that exhibited less common Nagel matches were selected for genetic analysis of their cone pigment genes to predict the corresponding peak wavelength separation of their two, long‐wavelength cone pigments. Conclusion The model predicts accurately the midpoint and the range for the spectral differences specified by the genes. 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. The anomaloscope is therefore not by itself sufficient to classify with certainty the colour deficiency involved.

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.