Color vision deficiency (CVD) is a very common condition among males, affecting as many as one in 12 men in the United States. The most common forms are deuteranopia (a deficiency of the green receptors), protanopia (a deficiency of the red receptors) and tritanopia (a deficiency of the blue receptors). Tritanopia is the least common CVD, and is not associated with X-linked inheritance. Interestingly, there actually may be an advantage to having a CVD. One study from the University of Edinburgh showed that individuals with red-green CVD are better at seeing camouflage! The researchers suggested that, because patients with a CVD lack certain color receptors, they learned to become more effective at pattern recognition during their lifetimes.