Color blindness, referred to by doctors as color vision deficiency (CVD), is said to occur more often in boys than girls and more often among European populations than African and Hispanic populations. A new study investigating CVD in four ethnicities of preschool children residing in California found that girls are indeed less likely to be color blind. Plus, the researchers also discovered that Caucasian boys have the highest prevalence, with one in 20 testing color blind, while African-American boys have the lowest: just 14 in every 100 passed the color identifying test.
The Multi-Ethnic Pediatric Eye Disease Study (MEPEDS) was designed to investigate the prevalence of vision disorders in 6- to 72-month-old children who were black, Asian, Hispanic, non-Hispanic white, and lived in Los Angeles and Riverside counties in California. The study’s purpose was to report the ethnicity-specific prevalence of congenital CVD among preschool children. A total of 5,960 subjects between the ages of 30 and 72 months were recruited for the study; of these, 4,177 were able to complete the color vision testing: 1,265 black, 812 Asian, 1,280 Hispanic, and 820 non-Hispanic white children. Color vision testing was performed using Color Vision Testing Made Easy color plates, and diagnostic confirmatory testing was performed using the Waggoner HRR Diagnostic Test color plates. After testing the children, the researchers discovered the prevalence of CVD among boys was 1.4 percent for black, 3.1 percent for Asian, 2.6 percent for Hispanic, and 5.6 percent for non-Hispanic white children; while the prevalence in girls was 0.0 percent to 0.5 percent for all ethnicities.
Why is this important? Often, children who have CVD do poorly on tests and assignments that use color-coded materials. "It's not that the child is not smart enough or bright enough, it's that they see the world a little differently," said Dr. Rohit Varma, chairman of the Department of Ophthalmology at the University of Southern California Keck School of Medicine. Varma, the study's principal investigator, suggested in a press release that children with CVD might benefit from different kinds of lesson plans or homework, adding, "That needs to start early on because labeling a child as not smart or bright enough is a huge stigma for the child and causes significant anxiety for the parents and family."
CVD is caused by the absence of color-sensitive pigment in the cone cells of the retina, the light-sensitive layer of tissue lining the back of the eye. When just one pigment is missing, a person may have trouble telling the difference between red and green (the most common type of color blindness). Achromatopsia is a rare and severe form of CVD which causes a person to see everything in shades of gray. The absence or presence of pigment is genetic; the red and green pigment genes are located on the X chromosome, and for this reason CVD occurs more often in boys than girls.
Source: Xie JZ, Tarczy-Hornoch K, Lin J, Cotter SA, Torres M, Varma R. Color Vision Deficiency in Preschool Children: The Multi-Ethnic Pediatric Eye Disease Study. Ophthalmology. 2014.