Serving in the role of medical examiner for the Federal Aviation Administration was a satisfying phase of my medical career.
After a decade or more of doing exams for third-class medical certificates (private pilots) and second-class medical certificates (commercial pilots), I qualified as senior examiner and performed first-class medicals for airline transport pilots.
On one such occasion, I encountered an apparently fit young man who was a graduate of the U.S. Air Force Academy. After 12 years as an Air Force pilot, he was eschewing the military for the airlines. In the infinite sarcasm of fighter pilots, he was leaving to drive the bus. His immediate problem, and mine, was he flunked the color-vision test – disqualifying him.
My head practically swirled as I contemplated how he possibly got through the Air Force and flew for 12 years color blind – or color vision deficient, as it is now termed.
Fortunately, I remembered FAA regulations allowed me to grant a medical certificate if a candidate could pass any of three designated color tests. Ethically and legally, he passed another test with no little relief for both of us.
Color blind people are not blind in the ordinary sense; they just see colors differently. Color perception begins on the retina in the small area known as the fovea (Latin, meaning small pit) centralis, which is densely-packed with “cones,” the color nerve-receptors. Their concentrated numbers provide us with 20/20 visual acuity and our central vision. Outside the fovea lie the “rods,” our black and white receptors, which provide 20/200 visual acuity and our peripheral vision. Unlike the cones, the rods are very sensitive at low light and constitute our night vision.
Most color vision deficiency is red-green, with the inability, partial or complete, to distinguish between the two. The deficiency is of genetic origin and occurs in 8 percent of males and 0.5 percent of females. The defect is found in the X chromosome and the related photo pigments in cones. The female XX, with its redundancy, outperforms the male XY configuration.
Even though color vision deficiency is not curable, it can be diagnosed at an early age. Undetected, it can render learning difficult and frustrating to an otherwise normal child.
Screening in Colorado, as in 41 other states, is mandated in schools, beginning in kindergarten – a true social vaccine. Because vision screening also detects other eye disorders, which are the most prevalent handicapping conditions of childhood, problems can be addressed, and chances of school success increased. Bravo for school nurses!
One more anecdote begs attention. An acquaintance came in for a third-class medical certificate, required for an aspiring private pilot.
He flat-out failed the color vision test, which simply restricted him from night flying. After minutes of absolute perplexity about the revelation of his “deficiency,” a light within began to shine: “That’s why my wife is always on my case about my color choices in clothing.”
www.alanfraserhouston.com. Dr. Fraser Houston is a retired emergency room physician who worked at area hospitals after moving to Southwest Colorado from New Hampshire in 1990.
