Most DMV vision tests include some form of a Snellen eye chart, the standard eye chart used to test visual acuity. People who have had an eye exam will likely be familiar with these charts; they have one big letter at the top (usually an "E") and several rows of gradually smaller letters below. A DMV employee will ask the driver to read certain rows to find out how well they can recognize the characters on the chart. They can measure the sharpness of a person’s eyesight based on the smallest row of letters they can read. Glasses or contact lenses may be worn during this part of the eye test, but only if they are required for driving. If this is the case, the state will place a restriction on the person’s license that requires them to wear their prescription lenses any time they are operating a motor vehicle. Some states also require a visual field test to be completed, which is used to check for peripheral (side) vision loss. During a visual field exam, the individual is directed to look straight ahead and watch for lights to the sides of their central field of view.