A Snellen chart is an eye chart that can be used to measure visual acuity. Developed by Dutch ophthalmologist Herman Snellen in 1862, it has since been improved and adjusted, but the eye chart itself remains largely unchanged. It is found in almost every ophthalmologist's office in the United States. The Snellen chart does not help ophthalmologists determine if you have an eye disease or retinal problem.
Depending on your risk factors and symptoms, your ophthalmologist may recommend more frequent examinations. If you don't wear glasses or contact lenses, your ophthalmologist will use the results to see if you need them. You will be given a card with 11 short paragraphs numbered from 1 (smallest letter) to 11 (largest letter). The Swiss ophthalmologist Edward Landolt developed a laboratory standard for measuring vision with or without glasses, known as the familiar eye test chart (Snellen).
This is seen from a distance of 6 meters (20 feet). Eye professionals can use certain tables to measure distance vision and others to measure near vision. Before the exam, your ophthalmologist will ask about your general health, including medications and family medical history.