BUTLER TWP — Color blindness is not a true blindness. It is more of a color deficiency, according to Dr. Michael McGrath, an optometrist with Butler Eye Care.

Color vision deficiency is an X chromosome linked condition that is more common in boys, he said. About 5 to 8 percent of boys have some type of color vision deficiency while only about 1 percent of girls have it.

People might have trouble seeing reds and greens, but they don’t instead see just black and white, he said. The red and green color vision deficiency is the most common.

People with red and green deficiency potentially could have issues with stoplights, but they should know that the red light is at the top of the signal and the green is at the bottom.

“There are different ways of figuring out how to deal (with color deficiency),” he said.

Another color problem, which is less common, is blue and yellow deficiency.

“Hardly any time will you have someone who is truly color blind and only sees black, white and shades of gray,” McGrath said.

He said there are some occupations that someone with a color deficiency might want to avoid. An example is an electrician because they need to know what color the wires are.

“If we know early enough that you have a color vision deficiency, then maybe you won’t choose a career that you need to discern certain colors,” he said.

The most common test for color vision deficiency uses the Ishihara color plates. This test has numbers inside circles.

McGrath said another test to determine the type and degree of the color deficiency is the Farnsworth Test, which has several levels.

“With the Ishihara you look at numbers on the plates, with the Farnsworth you take a whole bunch of small disks of different hues and you line them up,” he said.

To see if someone is truly color deficient, the first test to do would be the Ishihara to give the doctor a yes or no answer, he said. To know exactly the type of color deficiency, the next step would be the Farnsworth.

In childhood, most people don’t notice the deficiency until they are dressing themselves and can’t match colors, he said. Another way to discover it is a person might say something is one color, but it’s really another.

“In childhood you adapt to it, and you don’t really know it until other people notice it,” McGrath said. “They are not seeing just black and white, they are seeing different hues.”

Most color vision deficiency is hereditary, he said. However certain eye conditions, neurologic conditions and even some medications have been known to cause difficulties with color vision.

McGrath said the eyes are an extension of the brain and the nervous system. A problem in the central nervous system can cause color vision deficiency. A condition of the optic nerve can cause a new onset of a color deficiency.

Even a cataract, which is a cloudiness in the eye, can cause the color to seem washed out, but it is not truly causing a deficiency.

“Luckily there is an easy way to fix that — you get cataract surgery and then you vision is bright again,” he said.

As far as treating color deficiency, a doctor can help a patient develop certain cues on what they are seeing, he said. There are also tints that patients can get in glasses or contact lenses that help discern colors.

McGrath said most people are able to cope well with color vision deficiency in their daily routines.

“For the most part, people who have color vision deficiencies can live a completely normal life,” he said. “They just might need someone to help them pick out outfits.”