Someone with "20/30 vision" stands 20 feet from a reading chart but sees letters and objects that people with normal vision see 30 feet away from the chart, according to the University of Iowa. The first number, 20, is the distance from the eye chart and the second number, 30, shows the size of the letters read at that distance.Know More
A patient with 20/30 vision may need corrective lenses to see properly. The University of Iowa also explains that about 35 percent of Americans have 20/20 vision, meaning they see things normally. Having 20/20 vision describes someone who has sharp, clear vision at a distance. The American Optometric Association explains that other factors including depth perception, peripheral vision and color discernment determine a person's overall seeing ability.
The ability to see from a certain distance is measured by an eye chart hanging on a wall. The chart has 11 rows of letters, with a large "E" at the top. A patient able to read the "E" and nothing else on the chart has 20/200 vision, according to All About Vision. Having 20/200 vision is the definition of legal blindness in the United States. Drivers of vehicles need to have at least 20/40 visual acuity with corrective lenses. The line of 20/20 vision is the fourth row from the bottom of the chart. If a person can read the very bottom line of the chart, that person has 20/5 vision.Learn More
Adjustments to vision, such as blurry vision, can occur right after cataract surgery, states Mayo Clinic. Vision usually begins to improve a few days following surgery. Patients usually have a follow-up appointment within 24 to 48 hours after cataract surgery and a month later to monitor healing.Full Answer >
In order to be considered legally blind, a person must have a score of no better than 20/200 on a vision test while wearing corrective lenses, according to WebMD. The test may also be administered with a restricted field of vision, but the results must be the same.Full Answer >
The Farnsworth Lantern Test is a test of color vision. Test takers must identify the colors of two lights that may be any combination of red, green or white.Full Answer >
There are manufacturers who make decorative red contact lenses that can be worn with costumes; however, the lenses sold must be FDA approved. It is illegal for contact lens manufacturers to sell colored lenses to consumers that are non-prescription and unregulated.Full Answer >