An eye chart is a tool used by an optometrist or ophthalmologist to test your visual acuity (sharpness of vision). There are different types of charts such as the Snellen eye chart, 'Tumbling E' eye chart, and Jaeger eye chart. These charts use letters, patterns, or pictures. While some may measure visual acuity, others measure near vision. Some eye charts are designed for children, while others are meant for adults or both. The most recognized and used is the Snellen chart.