The macula is the small, central part of the retina that provides the most detailed vision.  Macular degeneration is an ageing change that disrupts the highly organised way in which the light receptors are positioned and reduces the ability to discern detail, without affecting peripheral vision.  Central vision becomes blurred and/or distorted.  The biggest risk factor for macular degeneration is age, but smoking is the major controllable risk factor; smokers are two to four times more likely to develop macular degeneration than non-smokers.  There are two main forms of macular degeneration, ''dry'' and ''wet''.  Dry macular degeneration tends to develop slowly but irreversably and currently cannot be treated.  Wet macular degeneration causes a relatively rapid drop in vision but if caught early enough can be treated by injections into the eye.  Regular eye examinations are extremely important in catching macular degeneration early.