A person with 20/50 vision is considered to have visual impairment, according to WebMD. Individuals with 20/50 visual acuity can see an object clearly at 20 feet away that individuals with normal vision can see clearly at 50 feet away.
Those with 20/20 visual acuity are defined as having normal vision, according to All About Vision. In general, to obtain a driver's license in the United States, a person must have a visual acuity of 20/40 or better. This can include the use of glasses or contact lenses. A person with a visual acuity of 20/200 or worse with the use of glasses or contacts is considered legally blind. A visual acuity of 20/10 or better indicates excellent vision, although very few people possess it.
Doctors use eye charts to determine visual acuity, according to All About Vision. One common eye chart, the Snellen eye chart, depicts 11 rows of uppercase letters. Each row of letters becomes progressively smaller toward the bottom of the chart. Visual acuity is measured by determining the smallest line of letters that an individual can read. The "tumbling E" eye chart is a different eye chart that is commonly used for young children or other individuals who are unable to read or recognize letters.