Final answer:
The Snellen test measures visual acuity by using a chart with letters of varying sizes.
Step-by-step explanation:
The Snellen test measures visual acuity. It uses a chart with letters of varying sizes to determine how well a person can see. The result of the test is a generalization of a person's acuity based on the size of letters they can read at a given distance. For example, if a person has 20/60 vision, it means they can read the smallest letters at 20 feet that a person with normal acuity can read from 60 feet away.