What is the recommended setup distance for the majority of vision charts during assessment?

The recommended setup distance for the majority of vision charts is 20 feet because this distance is widely recognized as optimal for assessing visual acuity. At 20 feet, the viewing conditions closely mimic the natural experience of distance vision, allowing for a more accurate evaluation of a person's visual capabilities. This standard distance helps ensure that any potential visual impairments can be identified effectively, as it provides a consistent backdrop for various types of vision charts, including Snellen charts.

Establishing the testing distance at 20 feet also aligns with practices in both clinical and educational settings, making it a universally accepted standard in eye examinations. This distance is particularly beneficial because it balances the need to avoid image distortion and provides enough separation to reduce any distractions that might interfere with the assessment process.