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 ...

Our ability to see with color vision depends on the presence and function of light-sensing pigments in the cones of our eyes. Color blindness, or color vision deficiency, happens when one or more of ...

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 ...

The most common types of color blindness, or color vision deficiency, are genetic. However, other types may develop due to injuries, eye diseases, health problems, and side effects of treatment.

Most individuals with color vision deficiency have had it since birth. However, people can develop it later in life. If it develops due to a health problem, color blindness can worsen over time. Color ...