What is a color vision test?
A color vision test, also known as the Ishihara color test, measures your ability to tell the difference among colors. If you don’t pass this test, you may have poor color vision, or your doctor may tell you that you’re color blind. However, being truly color blind is a very rare condition in which you’re only able to see shades of gray.
What causes poor color vision?
The most common type of poor color vision is an inability to distinguish shades of green from red. Poor color vision can be caused by:
- certain medications and diseases
- exposure to chemicals
According to Color Blind Awareness, about 1 in 12 men, and 1 in 200 women experience color blindness. The majority of people with color blindness have inherited the condition.
Sometimes, problems with color vision are due to a disease affecting your optic nerve, such as glaucoma. Poor color vision can also be the result of an inherited problem with the cones (color-sensitive photoreceptors) in your retina. The retina is the light-sensitive layer at the back of your eye.
Certain diseases can cause color vision impairment, including:
- macular degeneration
- Alzheimer’s disease
- Parkinson’s disease
- sickle cell anemia
Your color vision may improve if you receive treatment for the underlying condition.
You may want to have a color vision test if you think your color vision is deficient. If your child is receiving a standard eye exam, it’s a good idea to have them tested for both color vision and visual acuity. This can help address any potential problems early.
How do I prepare for a color vision test?
If you wear glasses or contact lenses, you should continue to wear them during the exam. Your doctor will ask if you’ve been taking any medications or supplements, if you have any medical conditions, and if there’s a history of poor color vision in your family.
This test has no associated risks, and no special preparation is necessary.
What happens during a color vision test?
Your eye doctor will administer the test. You will sit in a normally lit room. You will cover one eye, and then, using the uncovered eye, you’ll look at a series of test cards. Each card contains a multicolored dot pattern.
There’s a number or symbol in each color pattern. If you can identify the number or symbol, you’ll tell the doctor. Numbers, shapes, and symbols should be easy to distinguish from their surrounding dots if you have normal color vision. If you have color vision impairment, you might not be able to see the symbols. Or you may have difficulty distinguishing patterns among the dots.
After checking one eye, you’ll cover the other eye and look at the test cards again. The doctor may ask you to describe a particular color’s intensity as perceived by one eye versus the other. It’s possible to have a normal result on the color vision test but still experience a loss of color intensity in one eye or the other.
What do the results mean?
This test can help pinpoint several color vision problems, including:
- protanopia: difficulty distinguishing blue from green and red from green
- tritanopia: difficulty distinguishing yellow from green and blue from green
- deuteranopia: difficulty distinguishing red from purple and green from purple
- achromatopsia: complete color blindness (a rare condition, in which only shades of grey are visible)
What happens after a color vision test?
There’s no treatment that directly addresses color vision problems. However, if your color vision deficiency is the result of an illness, such as diabetes or glaucoma, addressing the illness may improve your color vision.
Using colored filters on your eyeglasses or colored contact lenses might make color contrasts easier to see. However, neither a filter nor colored contacts will improve your innate ability to tell colors apart.
What’s the takeaway?
Color blindness is not a painful condition and it shouldn’t affect your quality of life. However, some people with color blindness experience unpleasant effects, such as not noticing if they’re getting sunburned or not being able to tell if a banana is ripe enough to eat. If you think you or your child may be color blind, get a color vision test right away. If you have an underlying condition causing your color blindness, you may be able to treat your condition and reduce the effects on your vision.