Not smoking and eating a good diet can slow even hereditary macular degeneration.

Tufts University researchers have found that hereditary macular degeneration in identical twins progresses faster with increased smoking and is slowed by a good healthy diet.  The lead author said, "Eat a healthy diet with lots of fruits and vegetables, and that can make a difference - even if you have a genetic susceptibility to macular degeneration...and, if course, don't smoke."