Alphabet / E-Type
A Snellen chart is an eye chart that can be used to measure visual acuity.
- Positioning: You stand 20 feet (about 6 meters) from the chart. If the room is too small, a mirror may be used to simulate the distance.
- Testing: You cover one eye with your hand or an occluder and read the letters on each row aloud, starting from the top. You then repeat the process with the other eye.
- Reading the chart: The chart has 11 rows of block letters, with the top row having one very large letter and subsequent rows getting progressively smaller. The letters used are typically C, D, E, F, L, N, O, P, T, and Z, with specific line-to-gap ratios for consistency.
