Visual acuity is often described using a fraction, such as 20/20. This fraction indicates what a person with normal vision can see at 20 feet, compared to what the individual being tested can see at the same distance. A result of 20/20 is considered standard clarity. When a minus sign and a number follow the 20/20 notation, like 20/20 -2, it indicates a slight deficiency. In this instance, the individual can read the 20/20 line, but makes approximately two errors in doing so.
While 20/20 vision is often perceived as perfect, it simply signifies a specific level of clarity at a specific distance. It doesn’t account for other important visual factors such as peripheral vision, depth perception, color vision, or eye coordination. Historically, the Snellen chart, developed in the mid-19th century, has been the standard tool for assessing distance visual acuity. This system provided a standardized way to measure and compare visual capabilities across individuals.
