In 2002, those who had ever been diagnosed with macular degeneration were asked whether they had it during the past 12 months (MACDEGENYR).

The Field Representative's Manual defined macular degeneration as "when the macula, which is a small area in the eye where vision is sharpest, deteriorates. Central vision declines, making it difficult to do close work such as reading or recognizing faces. The person may still have side vision." This definition was not routinely shared with persons.