A color vision test, also known as the Ishihara color test, measures an individual’s ability distinguish different colors. Those who do not pass this test may have poor color vision or be considered “colorblind.” However, true “colorblindness” is a rare condition in which only shades of gray are seen by an individual.
Causes of Poor Color Vision
The most common form of color vision deficiency which results from a color vision test is an inability to distinguish shades of green from red. Genetics, aging, certain medications and diseases, and exposure to chemicals are all potential causes that affect that way colors are perceived. Statistically, males are more likely not to pass a color vision test in comparison to females.
Often, failing a color vision test indicates a chance of a disease affecting an optic nerve, such as glaucoma. Poor color vision can also be the result of an inherited problem with the cones (color-sensitive photoreceptors) in the retina. The retina is the light-sensitive layer at the back of your eye.
Certain diseases, including diabetes, alcoholism, macular degeneration, leukemia, Alzheimer’s disease, Parkinson’s disease, and sickle cell anemia can cause color vision impairment. Color vision test may also improve if an individual is treated for the underlying condition.
A color vision test is always beneficial, especially if you think that your color vision is deficient. If your child is receiving an eye exam, it is important for him or her to be tested for both color vision and visual acuity. This can help address any potential problems early and effectively.
Preparation for a Color Vision Test
If you or your child wears glasses or contact lenses they should be worn during the exam. The doctor will complete a rundown of questions to maintain the records of any medications, supplements, or medical conditions, and if there is a history of poor color vision in the family.
There are no risks associated with this test and no special preparation is required.
How a Color Vision Test is Performed
The eye doctor administers the test. The patient will cover one eye at a time is asked to look at a series of test cards. Each card contains a multicolored dot pattern.
There is a number or symbol in each color pattern so a child can easy understand without the need to have a reading or a numerical knowledge. The numbers, shapes, and symbols should be easy to distinguish from their surrounding dots if one has a normal color vision. If you have color vision impairment, you might not be able to see the symbols at all or will have difficulty distinguishing patterns among the dots.
After checking one eye, you will be asked to cover that eye and look at the test cards with the other. The doctor may ask you to describe a particular color’s intensity as perceived by one eye versus the other. It is 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.
Understanding the Test Results
There are several color vision problems that this test can help pinpoint:
- 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)
After a Color Vision Test
There is no treatment that directly addresses color vision problems. However, if your color vision deficiency is being caused by 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.