Color Blind Drivers: Is That A Problem?

AUTHOR: Dr. David Thorpe, President of Pass My Physical

The answer to this is a yes and a no.  The yes relates to the fact that drivers who are color blind frequently have trouble with passing certain tests administered by medical examiners so that they can obtain medical clearance and continue to driver as a commercial driver safely.  The question is not whether this should be tested, rather how and what is tested.  Medical examiners are all aware of the fact that drivers that have difficulties identifying certain colors can also be a danger to themselves and others while on the road.  That said, medical examiners often times confuse being color blind to being unable to drive safely.  This is far from the truth.


The regulation for vision is as follows:

“49 CFR 391.41 (b) (10): Has distant visual acuity of at least 20/40 (Snellen) in each eye without corrective lenses or visual acuity separately corrected to 20/40 (Snellen) or better with corrective lenses, distant binocular acuity of at least 20/40 (Snellen) in both eyes with or without corrective lenses, field of vision of at least 70° in the horizontal Meridian in each eye, and the ability to recognize the colors of traffic signals and devices showing standard red, green, and amber;

Therefore, the medical examiner should be determining the driver’s ability to properly distinguish the specific colors associated with traffic signals and devices.  That doesn’t mean any color red, any color green or any color amber or yellow.  On the contrary, and as many color blind drives are fully aware, there exits variations in color blindness, even to specific colors.  Consequently, the key is for a medical examiner to test for signal red, signal green and signal amber or yellow. 


Unfortunately medical examiners vary in the method of testing color blindness for driving, and often times use tools that make it difficult or impossible to determine if the driver can truly see the colors on traffic signals and devices.  Many use such tools as the ischihara color blind test.  It is a small booklet that contains multiple test plates with circles and dots appearing randomized in color and size.  Numbers of varying colors are situated within the dots.  If you can read the numbers you do not have any variation of being color blind.  If you cannot then you are color blind.  The problem with such testing is that it makes it very difficult for the drivers who can distinguish color differences, but maybe have red green deficiency specifically.  In essence it is designed to make it impossible for even minor deficiencies. 

Another problem can present itself can be the use of the colors on the Snellen Eye Chart.  This does represent the driver’s ability to see specific colors associated with a traffic signal but it has its issues too.  The problem that exists is that it is very easy to memorize these colors as there is not much variation between different charts.  Therefore it makes it too easy for the driver and does not truly test their ability to recognize these colors. 

Finally, one more questions always pops up from medical examiners and drivers alike.  Can the driver simply recognize the position of the color on the traffic light, and identify stop and yield signs as proof that they can distinguish color.  Unfortunately this is an emphatic no.  Believe it or not there are a number of traffic signals that are either old or relate to traditions for example, that have the colors on the traffic signal reversed or different than normal.  This exists in my community in upstate New York.  There is a traffic signal that has the green on top, that is there because it is an “Irish” neighborhood.  Obviously this would be a problem for any driver who was using the ability to see the positioning of the light vs the true color.   


The best way is to have either specific papers or cards available for the driver to randomly select which ones are signal red, green or amber.  By doing it this way, the driver is not very likely to fail the color blind test. As a matter of fact, in all of the years I have either been perform DOT exams or consulting with drivers, motor carriers and medical examiners, I have never seen or heard of a driver being disqualified to drive a CMV due to being color blind. 

So what if the medical examiner uses let’s say the ishihara test and a driver does not pass this.  First I would instruct the driver to politely question the use of this test and ask if there is another way of determining whether you can identify signal red, green and amber.  If no other way exists or in the event that the medical examiner chooses not to use a different method, then I would suggest you see an optometrist who is better able to determine variations of being color blind and can specifically determine a drivers abilities to distinguish colors.  Have them provide a note indicating your ability, and present this to the medical examiner.  Finally, make sure you keep a copy of that note and bring it with you to future medical exams so that you will have little problem moving forward. 

For additional questions and comments, please contact Dr. David Thorpe at!

Author: passmyphysical

Pass My Physical (PMP) is a DOT medical exam management platform that enables motor carriers to increase operating revenue, better fulfill regulatory requirements and reduce operating expenses. Why Pass My Physical?? (1) More operating revenue • Keep freight moving with more medically qualified drivers • Secure better freight rates by improving SMS scores (2) Lower regulatory administrative burden • Gain insight into the fleet’s certification status • Proactively respond to impending expirations (3) Less operating expense • Reduce medical certification costs by eliminating the need to retake the exam • Secure better insurance rates by improving SMS scores. Pass My Physical’s DOT medical exam management platform enables motor carriers to effectively eliminate most delays related to their drivers’ DOT physical exam. For more information visit our website at; OR contact us directly at

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