In a standard Snellen chart test, how far is the patient typically from the chart?

• A. 20 feet
• B. 10 feet
• C. 4 feet
• D. 100 feet

Answer: (A)

The test uses a fixed distance so that letter size corresponds to how well the eye can resolve details at that distance. At a standard testing distance, the line labeled for normal acuity is designed so that someone with typical vision can read it from twenty feet away. This distance standardizes the measurement and links what the chart shows (the letter size) to the actual acuity of the eye. If a patient can read that line at twenty feet, their acuity is considered normal (20/20); if they need to move closer to read it, their acuity is poorer. In many charts that distance corresponds to about six meters when using metric charts.