Age-related macular degeneration or AMD often advances slowly. In many older people vision loss does not occur for a long time. In others, the disease progresses faster and may lead to a loss of vision in one or both eyes.

People often first notice a blurred area near the center of vision. Over time, the blurred area may grow larger or they may develop blank spots in their central vision. Objects may appear less bright than before.

Macular degeneration does not lead to complete blindness; however, the loss of central vision in AMD can interfere with simple everyday activities — such as the ability to see faces, drive, read, write, or do close work, such as cooking or fixing things around the house. So macular degeneration can profoundly affect seniors' ability to function.

The researchers suggest that people who exercise are biologically younger than their less-active peers.

It appears, though, that AMD may be more avoidable than we have thought. A new study has found that if you smoke, drink or exercise you have a greater or lesser risk of developing the disorder — it all depends how much you do of one or another of these behaviors.

The study looked at the vision of over 1900 people aged 43 to 86 for twenty years. Participants were tested periodically for their ability to read letters, and their visual performance was reviewed along with the personal histories they gave regarding how much they smoked, drank, and exercised.

The study found that while visual impairment did indeed increase with age, the rate and risk were not the same for everyone.

Current smokers had a 65% greater chance of developing macular degeneration. The odds for heavy drinkers, those drinking four or more drinks a day, were even worse — they had a 166% greater likelihood of developing AMD.

Non-drinkers were not much better, with 95% increased odds. However, the researchers believe the results for non-drinkers may reflect advanced age or underlying medical conditions that may have been behind the lack of alcoholic intake, rather than non-drinking on its own.

Those who were physically active, defined in this study as engaging in regular activity with or without sweating three or more times per week, had their odds of being diagnosed with visual impairment cut by over half (58%).

The association between physical activity and improved vision has been demonstrated by other studies as well and the researchers suggest that people who exercise are biologically younger than their less-active peers.

While there were some differences in the measures for men and women, the overall trends were similar.

Although further research is necessary, the researchers contend that smoking, drinking, and physical exercise are all factors that can be modified by individuals and represent ways we can protect our vision into the future.

The study appears in Ophthalmology.