As a driver, you shouldn't overlook maintenance of two of your most vital safety devices: your eyes.

While you may have passed your licence bureau's eye test, some subtle but important vision problems may have gone undetected, says the American Optometric Association. Getting a more comprehensive professional examination won't force you to give up driving, the organization says. Rather, it will ensure that you will drive more safely.Some things that your optometrist or ophthalmologist will assess:

- Distance vision. While most states require 20/40 visual acuity, the measurement is made when you are standing still. When you're in a moving car, your acuity can change.

- Night vision. You can't see as well at night, and your accuity may drop from 20/40 to 20/60 after dark. You also must be able to adapt quickly to potential blinding effects of oncoming headlights.

- Depth perception. You need to be able to judge precisely the distance between your car and those in front or back of you on the road and those approaching from other angles.

- Peripheral awareness. This means your ability to detect objects and movement at the sides of your focal path. It's essential to spot pedestrians and other vehicles, and it helps you keep in the proper lane.

- Focal change. You should be able to switch your focus quickly between the road and dashboard and back again.

- Color perception. Obviously, you need to recognize traffic signals and signs by color as well as shape. But color also adds to your perception of people, objects and other cars.