Congenital Colour Vision Deficiency Research Articles

Development and validation of a new colour vision screener: A multi‐centre study

Aims/Purpose: The detection of acquired and congenital colour vision deficiency is of importance in the clinic for the early detection of ocular disease and determination of occupational suitability. Conventional methods of colour vision screening often fail to pass all normals and/or correctly identify those with acquired and congenital colour vision deficiency. The Colour Vision Screener (CVS) test [1] was developed to utilize an improved understanding of colour vision mechanisms to overcome the limitations present in conventional colour screening methods. This study aimed to use a robust multi‐centre methodology to fully validate the CVS test.Methods: Over 400 participants, including 124 normal trichromats, 166 deutans and 62 protans, were recruited from 10 international Colour Assessment and Diagnosis (CAD) testing centres. Each participant completed the CVS and the CAD test with calibrated visual displays. The red/green (RG) and yellow/blue (YB) CVS test sensitivity and specificity were established. The RG statistics were compared to the ‘gold standard’ reference for screening for RG congenital colour vision deficiency—the Ishihara pseudoisochromatic plate test.Results: The CVS test correctly identified ~99.1% of normal trichromats. All subjects with congenital RG loss and acquired loss on top of congenital RG deficiency were identified as having abnormal colour vision by the CVS. The Ishihara test, based upon 0 errors on the first 25 plates of the 38‐plate edition, correctly identifies ~80.6% of normal trichromats and 99.5% of subjects with congenital RG loss.Conclusions: Data collected across 10 international CAD centres demonstrate that the CVS can achieve a high sensitivity without sacrificing specificity. This multi‐centre study demonstrates that the CVS is quick, efficient, and easy to use and allows for the rapid and reliable screening of congenital and acquired colour vision deficiencies in large populations.Reference1. Barbur JL, Rodriguez‐Carmona M, Evans BEW. Colour vision assessment‐3. An efficient, two‐step, colour assessment protocol. Colour Research & Application 2021; 46: 33–45. https://doi.org/10.1002/col.22599

Prevalence of Congenital Color Vision Deficiency in Southern Taiwan and Detection of Female Carriers by Visual Pigment Gene Analysis.

This study aimed to investigate the prevalence of color vision deficiencies (CVDs) and determine whether carriers could be detected by analyzing the visual pigment genes. Materials and Methods: The data of students who underwent routine CVD screening using the Ishihara color test in Kaohsiung, Southern Taiwan were analyzed. Furthermore, the DNA samples of 80 randomly selected females and four obligate carriers were analyzed. The most upstream genes, downstream genes, and the most downstream genes in the red/green pigment gene arrays were amplified separately using polymerase chain reaction (PCR), and exon 5 of each gene was analyzed. The prevalence of congenital red-green CVD in this study was 3.46% in males and 0.14% in females. The PCR analysis of the first gene, downstream gene, and last gene revealed normal patterns in 73 normal cases. Seven unusual patterns were detected in two proton carriers and five deutan carriers. Among the randomly selected females, 8.8% (7/80) were CVD carriers. The prevalence of CVD among male Taiwanese students in this study was 3.46%. Female carriers of congenital CVD can be identified by molecular analysis of the visual pigment genes. The proportion of CVD carriers among the randomly selected females was 8.8%, which was slightly higher than expected and further studies are warranted.

The impact of display saturation on visual search performance in congenital colour vision deficiency.

Colour-related search tasks are common in many professional fields. The study investigated whether increasing chromatic saturation can enhance the visual performance of individuals with colour vision deficiency (CVD) in colour-related search tasks. 10 normal trichromats (5M, 5F; Mean (SD) age: 23.1 (3.3) years) and 15 individuals with CVD [8 deutans and 7 protans identified by HRR plates] (14M, 1F; aged 28.6 (8.7) years) participated in this study. Four naturalistic sceneries of everyday tasks/ birds, animals and flowers of 15 different colour combinations (1 pair of colours in each combination. e.g., 'brown/black' or 'red/green') were presented in 'low' saturation, 'original' (unaltered images) and 'high' saturation condition using the Psychopy program on a colour-calibrated monitor. On each trial, the subject was asked to identify a specific-coloured target. Overall, the visual search performance index (expressed as product of accuracy and a reciprocal of reaction time (%correct*s-1) of the normal trichromats [Mean (SD):77.76% correct*s-1 (16.32)] was significantly higher than CVD [45.71% correct*s-1 (18.95)] in the "original" test images (p = 0.001), but in individuals with CVD, there was no significant difference between 'original' [45.71% correct*s-1 (18.95)] and 'high' saturation condition ([47.43% correct*s-1 (20.07)]; p > 0.05). However, colour-wise, increased saturation showed improvements (≥ 10%) in protans mainly for 'red' combinations with other colours such as white (i.e., 'red/white'), purple, orange, grey, green, brown and black. The study suggests that increasing the saturation of certain colour combinations can potentially aid in the visual search performance of individuals with CVD. This knowledge will help in better counselling and management of the patients.

CON_PCA method to solve the human monochromacy color blindness

Color blindness is an inherited genetic ocular disorder. Acquired or congenital color blindness can become a major cause of problems in everyday life tasks. Contributing to solving the trouble of color blindness is important. Because the problem of color blindness leads to the non-discrimination of data seen by the infected person. Data visualization can contribute to solving the hassle of color blindness. This paper proposed a new technique using data visualization ideas that may contribute to easy data recognition. Our focus has been on monochromacy color blindness. The results are based on the famous Ishihara data sets measuring color blindness. The efficiency of the results was mathematically proven using equations and images via a website to simulate color blindness.

Colour perception deficits after posterior stroke: Not so rare after all?

Cerebral achromatopsia is an acquired colour perception impairment caused by brain injury, and is generally considered to be rare. Both hemispheres are thought to contribute to colour perception, but most published cases have had bilateral or right hemisphere lesions. In contrast to congenital colour blindness that affects the discrimination between specific hues, cerebral achromatopsia is often described as affecting perception across all colours. Most studies of cerebral achromatopsia have been single cases or case series of patients with colour perception deficits. Here, we explore colour perception deficits in an unbiased sample of patients with stroke affecting the posterior cerebral artery (N=63) from the Back of the Brain project. Patients were selected based on lesion location only, and not on the presence of a given symptom. All patients were tested with the Farnsworth D-15 Dichotomous Colour Blindness Test and performance compared to matched controls (N=45) using single case statistics. In patients with abnormal performance, the patterns of colour difficulties were qualitatively analysed. 22% of the patients showed significant problems with colour discrimination (44% of patients with bilateral lesions, 28% with left hemisphere lesions and 5% with right hemisphere lesions). Lesion analyses identified two regions in ventral occipital temporal areas in the left hemisphere as particularly strongly related to impaired performance in colour perception, but also indicated that bilateral lesions are more strongly associated with impaired performance that unilateral lesions. While some patients only had mild deficits, colour perception impairments were in many cases severe. Many patients had selective deficits only affecting the perception of some hues. The results suggest that colour perception difficulties following PCA stroke are common, and that they vary in severity and expression. In addition, the results point towards bilateral processing of colour perception with a left hemispheric domination, contradicting previous reports.

Effects of eye dominance on shade matching and color perception among the dentist population.

The purpose of this study was to evaluate the influence of eye dominance on color perception, and shade matching. A total of 104 participants were selected for the study. There were 3 groups: Group I: 3rd and 4th year dental students and interns (n = 40); Group II: postgraduates (n = 34); Group III: senior residents and faculty members (≥ 6 years of clinical experience) (n = 30). All participants were evaluated for congenital color blindness with Ishihara plates, their dominant eye with Mile's test, and their color perception with the Farnsworth-Munsell 100 hue test. The shade guide test was used for shade matching with a second corresponding set of Vitapan classical shade guides. The results of Mile's test revealed that 60.6% were right-eye dominant and 39.4% were left-eye dominant. There was a statistically significant difference among all participants between the dominant eye and the non-dominant eye in shade matching. The dominant eye has a positive effect on shade matching and the ability to match shades becomes better with an increase in clinical experience.

Determination of congenital color blindness in phase ii students of başkent university medical faculty

Determination of congenital color blindness in phase ii students of başkent university medical faculty

The prevalence of colour blindness among the males of the Bhoksha tribe in Dehradun, India

Colour Blindness is an X-linked recessive disorder which predominantly appears in males. Colour blindness is the inability or decreased ability to perceive colour differences by the human eye under normal lighting conditions. The purpose of the present study was to find out the prevalence of congenital Red-Green colour blindness among the people of the Bhoksha tribe in Dehradun district, Uttarakhand. The study was conducted with a total number of 204 individuals aged from 5 years to 85 years (mean ± SD is 22.71 ± 13.15) among the randomly selected male population. Colour blindness was examined using a standard Ishihara Chart under proper light. Among the total sample of 204 males in the community, 3 males are found to be colour blind which means that 98.53% were found to be normal, and the frequency of colour blindness was 1.47%. These three cases represented protanopia, deuteranopia and achromatopsia. Colour blindness appeared among the Pundir, Chauhan and Kakkad clans of the Bhoksha tribe in three villages. In conclusion, 1.47% were found to be colourblind in this study among the Bhoksha tribe of Dehradun, which is very high as compared with the prevalence in other tribal populations in India, although they were unaware of it. The present study supports Post and Pickford’s (1962, 1963) hypothesis of relaxation of selection.

Aids for color vision deficiency: introduction to the feature issue.

Approximately 8% of Caucasian males and 0.5% of females have congenital red-green color vision deficiencies (CVD), and a number of eye diseases are accompanied by acquired CVD. This feature issue includes ten contributions regarding existing and proposed algorithms and devices intended to help CVD subjects compensate for their color deficiencies. It also addresses limitations in the effectiveness of CVD aids for subjects with different types and degrees of color vision deficiency.

A large population study reveals a novel association between congenital color vision deficiency and environmental factors

The molecular genetics underlying color-vision deficiencies (CVD) has been established and widely studied. The aim of this study is to assess the associations between the prevalence of CVD and both genetics (place of origin) and environment (place of birth).

Coloured filters can simulate colour deficiency in normal vision but cannot compensate for congenital colour vision deficiency

Red-green colour vision deficiency (CVD) affects ~ 4% of Caucasians. Notch filters exist to simulate CVD when worn by colour vision normal (CVN) observers (simulation tools), or to improve colour discrimination when worn by CVD observers (compensation tools). The current study assesses effects of simulation (Variantor) and compensation (EnChroma) filters on performance in a variety of tasks. Experiments were conducted on 20 CVN and 16 CVD participants under no-filter and filter conditions (5 CVN used Variantor; 15 CVN and 16 CVD used EnChroma). Participants were tested on Ishihara and Farnsworth-Munsell 100 hue tests, CVA-UMinho colour discrimination and colour naming tasks and a board-game colour-sorting task. Repeated-measures ANOVAs found Variantor filters to significantly worsen CVN performance, mimicking protanopia. Mixed-model and repeated-measures ANOVAs demonstrate that EnChroma filters do not significantly enhance performance in CVD observers. Key EnChroma results were replicated in 8 CVD children (Ishihara test) and a sub-sample of 6 CVD adults (CVA-UMinho colour discrimination and colour naming tasks) for a smaller stimulus size. Pattern similarity exists across hue for discrimination thresholds and naming errors. Variantor filters are effective at mimicking congenital colour vision defects in CVN observers for all tasks, however EnChroma filters do not significantly compensate for CVD in any.

Chromatic discrimination in fixed saturation levels from trichromats and subjects with congenital color vision deficiency

Color vision tests use estimative of threshold color discrimination or number of correct responses to evaluate performance in chromatic discrimination tasks. Both approaches have advantages and disadvantages. In the present investigation, we compared the number of errors during color discrimination task in normal trichromats and participants with color vision deficiency (CVD) using pseudoisochromatic stimuli at fixed saturation levels. We recruited 28 normal trichromats and eight participants with CVD. Cambridge Color Test was used to categorize their color vision phenotype, and those with a phenotype suggestive of color vision deficiency had their L- and M-opsin genes genotyped. Pseudoisochromatic stimuli were shown with target chromaticity in 20 vectors radiating from the background chromaticity and saturation of 0.06, 0.04, 0.03, 0.02, 0.01, and 0.005 u’v' units. Each stimulus condition appeared in four trials. The number of errors for each stimulus condition was considered an indicator of the participant's performance. At high chromatic saturation, there were fewer errors from both phenotypes. The errors of the normal trichromats had no systematic variation for high saturated stimuli, but below 0.02 u’v' units, there was a discrete prevalence of tritan errors. For participants with CVD, the errors happened mainly in red-green chromatic vectors. A three-way ANOVA showed that all factors (color vision phenotype, stimulus saturation, and chromatic vector) had statistically significant effects on the number of errors and that stimulus saturation was the most important main effect. ROC analysis indicated that the performance of the fixed saturation levels to identify CVD was better between 0.02 and 0.06 u’v’ units reaching 100%, while saturation of 0.01 and 0.005 u’v’ units decreased the accuracy of the screening of the test. We concluded that the color discrimination task using high saturated stimuli separated normal trichromats and participants with red-green color vision deficiencies with high performance, which can be considered a promising method for new color vision tests based in frequency of errors.

Congenital Colour Vision Deficiency among Patients Attending Outpatient Department of Ophthalmology in a Tertiary Care Centre: A Descriptive Cross-sectional Study.

Congenital colour vision deficiency may affect a person's day-to-day activity and may also affect the choice of occupation a person chooses. This study aims to find the prevalence of congenital colour vision defects in patients presenting in outpatient department of Ophthalmology in a tertiary care centre. A descriptive cross-sectional study was conducted in a tertiary care centre after receiving ethical clearance from the Institutional Review Board of Kathmandu Medical College and Teaching Hospital (Reference number: 1006202102). The study was conducted for a 3 months period from 2021 July to 2021 September. Research participants were selected by the convenience sampling technique. A detailed ophthalmological examination was performed and colour vision was tested using Ishihara pseudoisochromatic colour vision chart. Only congenital colour vision defects were included in the study. Statistical Package for the Social Sciences version 20.0 was used for data analysis. Point estimate at 95% confidence interval was calculated along with frequency and proportion for binary data. The overall prevalence of congenital colour vision deficiency was 14 (5.24%) (2.54-7.86 at 95% Confidence Interval). The prevalence of congenital colour vision defects in females was 1 (0.74%) and in males was 13 (9.77%). The mean age of the participants with congenital colour vision deficits was 27.42±7.90 years. The prevalence of congenital colour vision deficiency was similar to the prevalence in other studies done in a similar setting. Awareness should be raised about this condition and people need to be screened at an early age to prevent disappointments in career choices later in life. colour vision defect; Nepal; prevalence.

Prevalence of Congenital Colour Vision Deficiency in Belagavi, Karnataka, India: A Hospital-based Cross-sectional Study

Introduction: Colour vision deficiency is a common ocular disorder, but it often goes unnoticed due to lack of awareness and screening programmes. If detected early in life, it can help people choose suitable career paths and genetic counselling can help reduce the birth of colour-blind children and future disappointments in life. Aim: To determine the prevalence of congenital Colour Vision Deficiency (CVD) among the general population in Belagavi at a tertiary level hospital and to spread awareness regarding CVD. Materials and Methods: This was a hospital-based crosssectional study, conducted at Jawaharlal Nehru Medical College, Belagavi, Karnataka, India (tertiary care hospital), from February 2022 to July 2022. The study population constituted 3131 people who visited the Ophthalmology Outpatient Department for routine eye examinations. A detailed ophthalmological examination was done, and colour vision was tested using Ishihara’s (38 plate) pseudoisochromatic test. Data was analysed using statistical software version 4.2.1 and Microsoft excel. Results: The mean age of the study population was 40.74±15.86 years. The overall prevalence of congenital CVD was 150 (4.79%). The prevalence of congenital colour vision defects was 13 (0.9%) in females, and 137 (8.12%) in males (p-value <0.001). Deuteranomaly was the most common type of congenital CVD, found among 88 (58.67%), followed by protanopia among 28 (18.67%), followed by protanomaly and deuteranopia, each accounting for 17 (11.33%). Conclusion: The prevalence of CVD among people belonging to the Belagavi district was remarkable. The p

The Effect of ChromaGen Contact Lenses on Corneal Clarity: A Corneal Densitometry.

Objectives:The purpose of this study is to investigate the effect of ChromaGen contact lens (CCL) on corneal clarity, expressed through the measurement of corneal densitometry (CD) values.Methods:This study included 22 eyes of 22 patients with congenital red-green color vision deficiency who were admitted to our clinic for the CCL trial. After a detailed ophthalmological examination and CD measurement with Pentacam HR (Oculus Optikgerate GmbH, Wetzlar, Germany), the most appropriate CCLs were defined through pseudoisochromatic plates and inserted for 2 h. The CD measurement was repeated after the removal of the CCL. Comparison was made of CD values before and after the insertion of the most appropriate CCL. The after-CCL/before-CCL ratio was calculated, and the effect of CCL type on this ratio was investigated.Results:The after-CCL values were higher in the anterior, central, posterior, and total thickness of the 0–2 mm concentric zone (p=0.044, p=0.040, p=0.021, and p=0.032, respectively) when compared to the before-CCL values. There was no statistically significant difference between before-CCL and after-CCL values in any layer of the 2–6, 6–10, and 10–12 mm concentric zones (p>0.05, for all). After-CCL/before-CCL ratios were similar in the Magenta2 (M2), Magenta3 (M3), and Violet3 (V3) types of CCLs (p>0.017).Conclusion:Usage for 2 h of CCL was observed to increase CD values in all layers of the 0–2 mm concentric zone irrespective of the type of CCL. Further studies with longer follow-up are required to determine the long-term effects and detect differing effects of CCL with different base curves.

Implications of inherited color vision deficiency on occupations: A neglected entity!

Purpose:To highlight the plight of individuals with congenital color vision deficiency (CVD).Methods:This is a retrospective study in which 191 electronic medical records of individuals with the diagnosis of inherited CVD, who visited the eye institute, between January 2010 and January 2021 were included. The inclusion criteria included diagnosis based on the failure in pseudoisochromatic plates (Ishihara / Hardy, Rand and Rittler (HRR) and age range between 18 and 35 years. The patient’s medical history, age, gender, type of defect, and preference for colored contact lenses was noted. Medical records were excluded if the participant had any other ocular pathology apart from congenital CVD.Results:At least 30% (57/191) of the individuals explicitly requested for color vision examination for a job-related purpose. Amongst them, the most common jobs aspired were army (~25%; [14/57]) followed by police (21%; [12/57]). There was only 2.6% (5/191) of individuals in which the type of CVD (protan/deutan) was classified. Only 5.2% of them (10/191) sought an X-Chrome contact lens trial.Conclusion:This study reported the occupational setbacks experienced by individuals with CVD. This study highlights the need to identify CVD at a younger age, thereby avoiding occupational-related setbacks later in life.

A large population study reveals a novel association between congenital color vision deficiency and environmental factors.

To assess the associations between the prevalence of congenital color vision deficiency (CVD) and genetics and environment, represented by place of origin (ethnic background) and place of birth, respectively. This is a retrospective study of the computerized database of the northern recruitment center of Israel of 53,895 consecutive male Jewish conscripts 16-19years old, who completed the medical profiling process between 1988 and 2011. CVD was diagnosed using the 24-pseudo-isochromatic plate Ishihara test. Associations of CVD prevalence with sociodemographic variables, anthropometric indices, refractive errors, and mainly place of origin and place of birth were tested by both univariate analysis and multivariate regression models. Elevated BMI (obesity) and blood pressure (hypertension), as well as myopia, were all positively associated with congenital CVD. The composition of the study population provides a unique opportunity to investigate the relationship between ethnicity and environment. The prevalence of CVD significantly differs among subpopulations of different ethnic background as well as among those who were born in different geographical locations. Additionally, differences in the prevalence of CVD (1.2-1.6%) were observed among conscripts from the same origin, who were born in Israel, compared to those who were born elsewhere. Both place of origin (p < 0.01) and place of birth (p < 0.05) were associated with the prevalence of CVD in a multivariable regression model. This study affirms previously established associations of CVD with certain variables and reveals a possible novel association of CVD with environmental factors.

Evaluation of the Cone Contrast Sensitivity Test in Normal Eyes and those with Congenital Color Blindness

ëª©ì  한국인 ì •ìƒì•ˆ 및 ì„ ì²œìƒ‰ê°ì´ìƒì•ˆì„ 대상으로 새로운 색각검사인 원뿔세포대비감도검사(ColorDx Cone contrast test HD® [CCT-HD]; Konan Medical, Inc., Irvine, CA, USA)를 í‰ê°€í•˜ê³ ìž 한다. 대상과 방법 건강한 한국인 ì •ìƒì•ˆ 66ëª , 125안 및 ì„ ì²œìƒ‰ê°ì´ìƒì•ˆ 25ëª , 50안을 대상으로 CCT-HD를 시행하였다. ì •ìƒì•ˆì—ì„œ 양안검사 결과의 일치도 평가 및 ì—°ë ¹ëŒ€, êµ¬ë©´ë Œì¦ˆëŒ€ì‘ì¹˜ì— 따른 CCT-HD ê²°ê³¼ 분석 및 ì„ ì²œìƒ‰ê°ì´ìƒì•ˆì˜ CCT-HD 결과와 비교 분석하였다. ê²°ê³¼ ì •ìƒì•ˆì—ì„œ 양안의 장(L), 중(M), 단파장(S) 원뿔세포대비감도(L-CCT, M-CCT, S-CCT) ì ìˆ˜ì˜ ìœ ì˜í•œ 차이는 없었다. 또한 ì—°ë ¹ëŒ€ì— 따른 L, M 및 S-CCT í‰ê· ì ìˆ˜ì˜ ìœ ì˜í•œ 차이는 ì—†ì—ˆê³ , êµ¬ë©´ë Œì¦ˆëŒ€ì‘ì¹˜ì™€ 각각의 CCT ì ìˆ˜ 사이에 ìœ ì˜í•œ 상관관계는 없었다. ì •ìƒì•ˆì—ì„œ L, M 및 S-CCT ì ìˆ˜ëŠ” 모두 75ì  이상이었다(ì •ìƒ 범위: ≥75ì ). ì œ1색각이상안의 í‰ê· L-CCT ì ìˆ˜ëŠ” 13.0 ± 13.2로 ìœ ì˜í•˜ê²Œ ë‚®ì•˜ê³ (p<0.001), ì œ2색각이상안의 í‰ê· M-CCT ì ìˆ˜ëŠ” 31.7 ± 16.6으로 ìœ ì˜í•˜ê²Œ 낮았다(p<0.001). CCT-HD 검사의 L-CCT와 M-CCT는 각각 ì œ1 및 2색각이상을 진단하는 데 100%의 민감도와 특이도를 보였다. ê²°ë¡ CCT-HD원뿔세포대비감도검사는 ì œ1 및 2색각이상의 진단 및 분류에 새로운 색각검사 장비로써 ìœ ìš©í• ê²ƒìœ¼ë¡œ 기대된다. Keywords: Color vision test, Cone contrast sensitivity test, Congenital color vision deficiency

Prevalence of colour vision deficiency in the Republic of Ireland schoolchildren and associated socio-demographic factors

ABSTRACT Clinical relevance Early screening is essential to counsel schoolchildren with congenital colour vision deficiency (CVD) in determining their future career path and to advise teachers of the impact of CVD on classroom difficulties. Background Congenital CVD is an X‐linked genetic abnormality relatively commonplace in humans. This study aimed to determine the prevalence of congenital CVD in the Republic of Ireland schoolchildren and associated socio‐demographic factors. Methods A total of 1,626 schoolchildren (882 boys and 744 girls), in two age groups (728 aged 6–7-years and 898 aged 12–13-years) were examined from randomly selected schools. Colour vision testing was carried out using the Richmond Hardy‐Rand‐Rittler pseudoisochromatic test for colour vision (fourth edition); diagnostic plates were used to determine CVD type and extent if participants failed to identify symbols on the screening plates. Results CVD was detected in 73 boys (8.3 per cent, 95% confidence interval (CI) 6.6–10.3) and in 13 girls (1.8 per cent, 95% CI 1.0–3.1, p < 0.001). As expected, deutan (boys 4.8 per cent, girls 0.8 per cent) was the most common type of CVD, followed by protan (boys 1.7 per cent, girls 0.1 per cent), unclassified red/green CVD (boys 1.2 per cent, girls 0.8 per cent) and then tritan (boys 0.5 per cent). One case of achromatopsia was detected based on failure on all diagnostic plates. Traveller participants (boys 21.0 per cent, girls 8.6 per cent) had a higher CVD prevalence than their White non‐Traveller (boys 7.2 per cent, girls 1.0 per cent) and non‐White (boys 5.4 per cent, girls 1.1 per cent) counterparts (odds ratio 3.00, 95% CI 1.1–8.1, p = 0.006). In boys, CVD was also associated with twin birth (odds ratio 2.7, 95% CI 1.1–6.7, p = 0.03) and low birthweight (p = 0.04). Conclusion This investigation of CVD in the Republic of Ireland schoolchildren should alert clinicians to the association between CVD and Traveller ethnicity, twin birth and lower birthweight. The prevalence of CVD found was similar to previous studies involving predominantly White populations and higher among Traveller participants; hence, counselling regarding inherited anomalies in the Traveller community is recommended. Early screening is essential to counsel schoolchildren with CVD in determining their future career path and to advise teachers of the impact of CVD on classroom difficulties.

Commentary: Significance of early screening for color vision in children.

One of the most common inherited vision disorders is congenital color vision deficiency (CVD). Its prevalence in men can be as high as 8% and 0.5% in women.[1] Men are predominately affected by the X-linked inheritance pattern, while women become carriers of the abnormal gene.[2] There are also different causes for acquired color vision defects, such as ocular or neurological disease, some metabolic disorders, drug toxicity and exposure to certain solvents.[3] Congenital CVD results from genetic mutations that affect the expression of the full complement of normal cone photoreceptors. They’re divided into three categories based on their intensity (anomalous trichromacy, dichromacy, and monochromacy). CVD places the sufferer at a distinct disadvantage when performing certain visual tasks—in particular those tasks in which a colored target is embedded in a variegated background of a different color. CVD affects many areas of life, and its adverse impact is experienced at all stages, i.e., from childhood to adolescence and adulthood.[45] Population is one of the biggest problems in India and the reason for so many compromises starting from lack of resources at every level. Healthcare is just one example. When providing even simple vision assessment in school children becomes a big task few tests like color vision examination is rarely being performed. Population diagnosis is usually late at the time of medical examination at the time of higher education or specific job. They are rarely diagnosed early in life. Late diagnosis leads to rejection for a particular job most of the time which has a psychological impact on individuals. In India where an education system doesn’t give a student to choose multiple streams, it turns out, several professional choices can be negatively impacted by a color blindness diagnosis. CVD is a hidden disability because, though present from birth, its role comes to play only when children begin to attend regular schools to learn some tasks.[6] From here onwards process of considerable difficulties in learning starts. Children with CVD are frequently marked as lethargic students, which could mentally affect them, or could evoke negative responses from instructors and guardian. This can lead to not only problems in learning but also in playing and in their social bonding. Various studies have been carried out all over the world to see the prevalence of CVD among school children.[789] Xie JZ, et al.[10] suggested that successful CVD testing can be done starting at age four. Cole stressed that school children should know if they have CVD so they can be helped more quickly to find adaptive strategies and be able to take it into account when planning their career.[11] Largest study on CVD in children is conducted to see the burden of this disability in India.[12] Authors have used Dalton’s psuedoisochromatic plates for color vision screening. It is based on Ishihara color vision chart principle. The Dalton screener consists of 6 sets with 4 plates in each that includes one demo plate and three screening plates. Those, who failed to read three or more plates in two or more random sets of the Dalton’s pseudoisochromatic plate were considered to have CVD after confirming with Ishihara’s PIP color vision testing (38 plate edition). The result shows CVD among boys was found to be 2.76%. Children from urban region (3.17%) were more likely to be color vision deficient than children from rural region (1.79%). These results are similar to the other parts of the country and few other countries from Asia. Screening of CVD is relatively easy does not require any formal training and can be performed by any assigned staff. Various plate tests are available, such as Ishihara, Tokyo, HRR plate test, which are highly sensitive and specific to detect CVD. Because of rapidly evolving technologies with more and more use of color coded tasks in each sector including education sector and specific job requiring color differentiation, the efforts should be made at a fundamental level in screening of color vision defects during comprehensive school eye health programs. Since CVD is congenital and there is no permanent cure for it. However, advice at an early age could help to find adaptive strategies, which enable them to avoid disappointments in the choice of their future career. Parental education, awareness, genetic counseling strategies in the regions with high CVD incidence could help a lot in minimizing the occurrence of the disorder among their offspring.