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Combo test confirms color blindness with DNA sample
MILWAUKEE — A new color blindness test is being used effectively in preschoolers as well as in older children to detect both the presence of color vision defects and their severity.
“I’ve become a very strong proponent of not only testing for color blindness early, but also of talking to parents about the implications of these children being mislabeled as learning disabled because of their color vision defect,” said Jay Neitz, PhD, associate professor of cell biology, neurobiology, anatomy and ophthalmology at the Medical College of Wisconsin. Dr. Neitz developed the Neitz Test of Color Vision along with his re search partner and wife, Maureen E. Neitz, PhD, associate professor of ophthalmology.
Child-friendly test
The newly patented test comprises two parts: a paper-and-pencil test and a follow-up DNA test. The paper-and-pencil test can be administered under ordinary lighting by a teacher who has no special training. It takes about 10 minutes. The follow-up DNA test is administered only to those children whose initial test indicates that there is a color vision defect and supplies only information about color blindness.
“We were looking for a very quick and inexpensive test that would supply information only about color blindness, so we use specific probes that identify only genetic information that comes from the genes that encode the visual pigments,” Dr. Jay Neitz said.
“The child writes directly onto the piece of paper, so it’s unlike standard plate tests,” he told Ocular Surgery News. He added that this test does not in corporate the type of scripted numerals used, for instance, in the Ishihara Test be cause children under the age of 8, “don’t reliably recognize those numerals.”
Dr. Jay Neitz added that the test was developed in response to a request from Prevent Blindness Wisconsin, which was looking for a color blindness test that could be administered en masse throughout the state at the kindergarten level. After the Neitzes mulled the request, they realized none existed, so they began to design one of their own.
“The very first thing that they teach children in kindergarten is their colors, and once they know their colors, they use that as a basis for teaching everything else,” Dr. Jay Neitz said. He says color blindness is not taken very seriously, “yet it affects these children in a very profound way if they’re labeled as not being able to learn or not being able to follow direction because of their color vision defect.”
Current research reports that 8% to 10% of all boys and one in 230 girls is color blind, and the Neitz Test of Color Vision produced similar results when administered in a field study to 5,058 children at 14 Wisconsin elementary schools. According to Dr. Jay Neitz, the severity of color blindness breaks down as such: “Two percent are very bad off, 2% have something that’s very minimal, and the remainder of them are somewhere in between,” he said.
Applying the lessons
The Neitzes are applying the lessons learned from their color blindness re search to other kinds of genetic defects that cause visual impairment. “The thing that happens in red/green color blindness is that people are missing one class of cones. If you have a defect that effects more than one class of cones, you don’t have color blindness any longer; you now have a more debilitating disease. In fact, we know very clearly that there are blinding disorders that are caused by exactly the same defects and exactly the same genes as color blindness, and rather than just affecting the white class [of cones], they affect two or more classes,” Dr. Jay Neitz said.
“We suspect that even things like age-related macular degeneration involve the very same kinds of mechanisms that cause color blindness. It’s just that with color blindness, the defect happens very early, while [with AMD] the defect affects both the red and green cones over a much longer period of time,” he added.
For Your Information:
- Jay Neitz, PhD, can be reached at the Medical College of Wisconsin; (414) 456-8457; fax: (414) 456-6517. Dr. Neitz has no direct financial interest in any of the products mentioned in this article, nor is he a paid consultant for any companies mentioned.