As the weather warms and days get longer, millions of senior citizens take to the road to vacation and visit family. But before they hit the road, experts say, they should have their vision checked, because changes in aging eyes require extra attention.

Compared with their counterparts from previous generations, today's elderly are healthier, more active and more likely to hold a driver's license longer. But as people age, sight, hearing, reflexes and ability to judge speed and distance diminish. Increas-ing numbers of people also are affected by more severe vision problems caused by macular degeneration, glaucoma and cataracts. Even medications can cause blurred eyesight.

Changes happen gradually, so some older adults might not notice the impact on driving ability. Studies show that more than 25 percent of Americans over 65 have not had an eye exam in two years.

All elderly drivers should have regular eye exams to maintain eye health and ensure that their ability to drive safely is not compromised by undetected vision loss, says Ken Higgins, vice president for vision science at Lighthouse International, an organization that helps those with vision problems.

"If you are 60 years of age or older, know that you're driving with only about one-third of the light you had when you were 20 because of changes occurring in the eye," says Higgins. "Also keep in mind that, as an older driver, you can't process and respond to visual information as quickly and efficiently as you could when you were younger."

Dr. Ellen McMahon, of the Center on Aging at the University of Connecticut Health Center in Farmington, says seniors who are experiencing difficulty locating familiar places, driving at posted speeds or obeying traffic signals should consider alternative travel plans.

"If you see one or more of these signs in an older person, it makes sense to talk about driving safety," says McMahon. "Frequently, once the topic is raised, older drivers may regulate their own driving behavior. They may stop driving long distances, or they may avoid driving at night or during rush hours."

Older drivers who get the green light for extended trips can help compensate for age-related vision loss with some simple changes to their driving routines. Shorter driving days, frequent stops and regular meals can make a trip safer and more manageable.

Korky Vann is a free-lance writer for the Hartford Courant, a Tribune Publishing newspaper.