Question
Nurse Red,
I was asked a question today and I told this person that I would post the question here because I haven't a clue as to the correct answer.
We were talking about those wonderful pages of dots where there is a number that you are required to make out. If a person cannot make out what that number is, can they still pass the vision requirement for their CDL license?
This man admits to being somewhat color blind but states that he can distinguish the differences in traffic lights without trouble.
Thank You!
Mary
Answer
Mary,
This is a really good question.
The test you are referring to is the Ishihara test. The test is fairly simple to administer, but the interpretation of the test result is complicated. This type of test can determine varying TYPES and degree of color blindness. The term color blind, in itself, is a very generalized term. Some people have difficulty with certain colors and others have trouble with shades of color. The Ishihara test is supposed to determine and differentiate these factors.
Very often, the person administering the test is a medical technician or someone other than the doctor. In an ideal situation, that person understands the test they are administering and records the results accurately for interpretation by a physician. Errors can be made if that person isn't well trained on administering this particular type of test.
The DOT regs state that the driver must be able to distinguish red, green, and amber colors only. A standard Snellen vision chart (that's the one with all the letters of varying sizes) only has the red and green colors on it. This is the most commonly used vision test for DOT medical certification. But because this test does not contain the color amber, it is often supplemented by the Ishihara testing or some other type of test that will include the three colors I have mentioned.
At our clinic, we have a set of three cards that we use to determine the drivers ability to correctly identify red, green, and amber.
It is a much simpler test to administer and interpret. Leaving much less room for error.
As I have often stated in the past, some companies have higher standards of medical certification than what is called for in the Federal Regs. (which are the MINIMUM requirements for certification). This is quite legal. However, most companies only require that drivers meet the DOT standards.
So, to answer your question. In most situations, your friend will pass. If he or she happens to apply to one of the stricter companies, there may be a problem.
By the way, traffic lights are not always what the driver needs to be able to distinguish colors for. Various emergency vehicles use different colored lights to identify themselves to others. For instance, tow vehicles use amber lights. Picture the driver who can't see or distinguish the color amber and you've got a driver pulling over to get out of the way of a tow truck! Or not moving over for a firetruck because he thinks it is a tow truck!
Many states use the color blue to identify police vehicles. Blue is not mentioned in the regs, but you can see where it may create a problem if the driver can't see blue. This is where a company may wish to impose higher standards for their drivers.
Keeping you safe, healthy, and on the road.
Nurse RedVisit us at
Answer
In the 2nd grade my teacher was puzzled why I could not identify the color purple. I always said it was red, or blue if the shade was light enough.
We finally decided I had some color problems.
When I joined the military they ploped that book in front of me and asked me to recite the numbers. "Yea, right", what comes after the number 2 on the first page? It's still a mystery to me.
I can not see most pastel colors, or correctly, I should say I identify them as something else.
A few years ago I complimented my wife on her choice of prety blue undies ... was informed they were not blue, and the challenge was on!
Seems they were indeed green. She finally settled for the fact I appreciated them, no matter what color I "thought" they were.
A standard color test for me is a random test of a non standard product like a yellow pencil, a red bottle cap, a green cup. This is also an acceptable method.
As for the color blue, for those of us most likely to be bothered by color perception, the color blue is EASIEST to see.
Red in the day time simply does not exsist for me. When the scales have their open/closed signs in red neon, and the sun hit's it .. it may as well be blank.
I once saw a sign along the Interstate that had bright red on bright blue background. I never did know what it said .. the bright blue just sort of washed the red from the picture.
States need to realize this when they plan on making signs or warning lights a non standard color.
Monty