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Sharpness of Vision & Changing Focus

To get a driver’s license in the United States, requirements for best-corrected visual acuity, or best distance vision with eyeglasses or contact lenses, varies widely from state to state.

People with normal visual acuity are considered to have 20/20 vision. This means being able to read a letter positioned 20 feet away. Not everyone has 20/20 vision, of course. For example, if you have 20/100 vision, that means you must be 20 feet away from a letter to read it, compared with someone with normal visual acuity who could read it from 100 feet.

If you have trouble with your vision and notice a change in what you see while you’re driving, it’s best to get a vision test to determine potential nearsightedness (myopia) or farsightedness (hyperopia). It is also possible to have both nearsightedness and farsightedness.

Myopia, or nearsightedness, occurs when the eyeball is slightly longer than usual from front to back. Nearsightedness runs in families and usually appears in childhood, but it affects senior drivers as well. This problem may stabilize at a certain point, although sometimes it worsens with age. This is known as myopic creep. Nearsighted people have difficulty reading highway signs and seeing other objects at a distance, but can see for tasks such as reading or sewing.

Nearsightedness may be corrected with glasses, contact lenses or eye surgery. People with myopia may need to wear glasses or contact lenses all the time or only for distance vision, such as when driving.

Hyperopia, or farsightedness, is a common vision problem. Senior drivers with hyperopia can see distant objects very well, but have difficulty focusing on objects that are close.

For senior drivers, farsightedness can be corrected with glasses or contact lenses to change the way light rays bend into the eyes. If your eyewear prescription begins with plus numbers, like +2.50, you are farsighted and may need to wear glasses or contacts all the time or only when reading, working on a computer or doing other close-up work.

As you age, your useful field of view gets smaller and you no longer see everything that may be a safety risk. Below is what your useful field of view probably was at age 16.