Snellendiagramm

A Snellendiagramm, also known as a Snellen chart, is a visual acuity test used to measure a person's visual clarity. It consists of a series of letters arranged in rows, with each row containing letters of decreasing size. The chart is typically placed at a standard distance from the viewer, usually 6 meters, and the viewer is asked to read the smallest row of letters that they can clearly see. The result is recorded as a fraction, where the numerator represents the size of the letters in the smallest row that can be read, and the denominator represents the distance at which the chart is viewed. For example, if a person can read the 20/20 row, it means that they have normal vision at 20 feet (6 meters). The Snellendiagramm is widely used in optometry and ophthalmology to assess visual acuity and monitor changes in vision over time. It is named after its creator, Herman Snellen, a Dutch ophthalmologist who developed the chart in 1862.