Each time drivers in the United States renew their driver's license a vision test is required. Right? Wrong. Surprisingly, regular vision tests aren't required everywhere. And according to a recent report by the Vision Council of America, of the 10 states with the highest number of fatal car crashes, four require no vision screenings after the initial license application and four only require screenings every eight or more years.

Vision requirements for licensing vary from state to state. According to the Vision Council of America, all states require that applicants for a new license have at least 20/40 best-corrected vision (the best vision possible with glasses or contacts), a 70-degree field of vision (the range of vision you have when looking straight ahead), and the ability to see the color of traffic lights. To find out the requirements for your state, contact your department of motor vehicles.

The American Academy of Opthalmology recommends that everyone between ages 40 and 65 have an eye exam every two to four years. And if you're over age 65, see your eye doctor every one to two years, particularly to check for conditions such as cataracts, glaucoma, and age-related macular degeneration. The American Optometric Association recommends more frequent screening -- every one to two years for people ages 41–60 and annually for anyone age 61 and older. Between check ups, if your vision changes or you have trouble driving at night, let your eye doctor know right away.

Upgrade Your Eyewear -- You may also want to investigate antireflective lenses for your eyeglasses. These lenses minimize glare and allow more light to enter the eye than regular plastic lenses, which let only 91% of available light enter. Antireflective lenses are especially helpful at night, cutting the reflections on your lenses from streetlamps and headlights.

Polarized sunglasses also may be helpful especially for reducing glare. Polarized lenses have a laminated surface that contains vertical stripes, which allows the light to enter a lens vertically, blocking the horizontal bright light.

Prepare Your Car and Know Your Limits -- There are a number of steps you can take for a safer driving experience.

• Keep your headlights, taillights, mirrors, and windshields clean. These may sound like housekeeping details, but they can improve your road vision. Give your eyeglasses a shine before you set out as well.
• Keep a spare pair of eyeglasses and sunglasses in your glove compartment so that you never find yourself driving without a pair handy.
• If you're buying a car, skip the darkened or tinted windows. Also, pick a model with easy-to-read symbols, large dials, and an instrument panel that brightens well at night. In addition, ask for a rearview mirror that automatically filters out glare.
• When you have your car serviced, make sure the lights are at full power and properly aligned so they don't affect the vision of drivers coming toward you.
• Plan long road trips with your eyes in mind, stopping every few hours to rest your body and your eyes.
• Avoid traveling at night, dawn, and dusk, especially in places you don't know well. And skip the crowded highways for quieter routes.
• If you know you're uncomfortable driving, consider taking a refresher class. Refresher classes are offered by the AARP, The Automobile Association of America (AAA), and the National Safety Council. Another option is to work on improving your driving skills with a driving instructor or vision rehabilitation specialist.
• If you take prescription medicines, such as antihistamines or blood pressure medication, check with your doctor about whether they may affect your vision.