Commentary: Significance of early screening for color vision in children

Abstract

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.[4,5] 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.[7‐9] 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.