Color Vision and Point of Care Testing
An early physical exam included a test for color blindness. I was shown a book of dotted pictures with numbers “hidden” inside them (sometimes called Ishihara diagrams). If I could see all the numbers, my color vision was fine. If not, I would have to find a different profession. Color vision, I was told, is essential to performing lab testing.
Color blindness is caused by a defect in retinal cone cells that affect how they absorb light. Cones sense red, green, or blue light, so these are the colors affected in variations and degrees. Since many test interpretations rely on color indicators, it makes sense that laboratory workers would need to see them accurately.
I’ve no idea if current programs require a color blind test, since there are few manual methods left. But these few are important: urine dipsticks, bacterial colony assessment, Gram stain, etc. Our procedures often reinforce the importance of accurate color vision. I can imagine most lab techs take it for granted.
But what about doctors and nurses performing point of care testing? Are any color blind?
Possibly. Color blindness affects more males (7%) than females (0.5%), because it is usually a sex-linked inherited disorder. In female-dominated professions such as nursing, this wouldn’t seem to be a significant issue. But there are plenty of males, just the same.
I had never considered the issue until a nurse asked, “Do you need nurses performing lab tests to be tested for color blindness?” Asking it tells me that nursing may not require testing. And if we want to start, how do we find out and what do we do with the information? Competency assessment won’t discern all variations. As straightforward as Ishihara diagrams seem -- there are online tests -- the cause isn’t always genetic. I’m not qualified to diagnose, that’s for sure.
Who gets tested, when, and what do we do with the results? Will a hospital add it to preemployment physicals if only the laboratory requires it? The issue has shades of gray. Let me know if you have run across this problem.