Final answer:
The Snellen chart is used to test visual acuity by presenting standard Roman letters in various sizes.
Step-by-step explanation:
The Snellen chart is used to test visual acuity. It is a chart that presents standard Roman letters in various sizes. The result of this test gives a rough indication of a person's ability to see based on the normal accepted acuity. For example, a person with 20/60 vision can see the smallest letters at a 20-foot distance that a person with normal acuity can see from 60 feet away.