What is an eye test? Eye charts and more explained
During an eye test, your eye doctor will use a chart of letters ("eye chart") to measure how well you see objects at least 20 feet (6 meters) away. This is called distance visual acuity testing.
The classic example of an eye chart is the Snellen eye chart, developed by Dutch eye doctor Hermann Snellen in the 1860s. There are many variations of the Snellen eye chart, but in general they show 11 rows of capital letters. The top row typically contains just one letter (usually the letter 'E'). The other rows contain letters that are progressively smaller in size, with more letters per line.
Original Article Source Credits: All About Vision , https://www.allaboutvision.com/
Article Written By: Liz Segre
Original Article Posted on: Gary Heiting, OD
Link to Original Article: https://www.allaboutvision.com/en-ca/eye-test/free-eye-chart/