What is the recommended distance used for assessing distance acuity?

The recommended distance for assessing distance acuity is 20 feet. This standard has been established to allow for accurate measurement of visual acuity using standardized eye charts, such as the Snellen chart. At this distance, the size of the letters on the chart is calibrated to measure visual clarity effectively without distortion caused by proximity.

When testing at 20 feet, the eye’s ability to resolve different levels of detail can be accurately assessed under normal conditions. Testing farther than this can provide a larger view but may not add significant value to the acuity measurement, while testing closer may not accurately reflect how one would see at greater distances, which is particularly crucial for driving and other activities that require keen distance vision. Therefore, 20 feet serves as a universal benchmark in clinical practice for assessing distance visual acuity.