This document outlines the procedure for conducting a Snellen eye chart vision test. It defines the test as the standard method for measuring distance visual acuity using an eye chart. The test is done by having a patient read letters on the chart from 20 feet away to determine their visual acuity score, such as 20/20 or 20/40 vision. A legally blind designation requires a score of 20/200 or worse. The procedure involves having the patient cover one eye at a time and read down the chart to find the smallest line of letters they can read clearly from 20 feet.