The chart provided a standard for eye doctors to use when measuring a patient’s eyesight. The chart has 11 lines of capitalized block letters, known as optotypes.Īt the top of the chart is only one letter - a large “E.” As you move down the rows of the chart, the letters gradually get smaller. Snellen created his chart using a geometric scale that gives an exact measurement of a person's visual acuity. Donders conducted eye exams by having people look at a chart on the wall and describe what they could see.ĭr. Herman Snellen, a Dutch eye doctor, created the eye chart in 1862 for his colleague, Dr.
The Snellen chart is an eye chart that measures a person’s vision by how well they can read and see detail.
The farther down the chart the patient can read, the better their visual acuity is. During an eye exam, patients will read the Snellen chart from 20 feet away. The Snellen eye chart is the most common method used by eye doctors to measure visual acuity, which is how clearly a person can see.
