A color vision test, also known as the Ishihara color test, measures your ability to tell the difference among colors. If you don’t pass this test, you may have poor color vision, or your doctor may ...

There are three main types of color vision deficiency: red-green, blue-yellow, and complete. Color blindness, or color vision deficiency, affects the way you perceive color and can make it hard to ...

Impaired vision and blindness are common. About 3.4 million people in the US are blind or visually impaired. Vision is usually measured by visual acuity charts, and normal vision is expressed as 20/20 ...

The swirling skies of Vincent Van Gogh's Starry Night illustrate a mystery that has eluded biologists for more than a century -- why do we perceive the color blue in the dimly lit night sky? A newly ...

In order to see the red of a sunset or the green of spring leaves, developing human eyes need to get the right hormone at the right time. That's the finding of a team of scientists who studied how ...