A new insight has pointed out that early-stage age-related macular degeneration (AMD) is connected to risk factors, like smoking and low levels of high-density lipoprotein.
The condition appears uncommon before age 55 but the risk increases with age thereafter.
Ronald Klein, of the University of Wisconsin, Madison, and colleagues assessed 2,810 individuals age 21 to 84 participating in the Beaver Dam Offspring Study.
The presence and severity of drusen-yellow or white deposits in the retina, an early sign of AMD-was determined, along with that of other characteristics of AMD.
Early AMD was present in 3.4 percent of the participants, with rates varying from 2.4 percent in those age 21 to 34 to 9.8 percent in those age 65 years and older.
Besides age, other factors associated with increased risk for AMD included being male, smoking more heavily for a longer period of time, and being hearing impaired, whereas having higher levels of HDL cholesterol was associated with reduced risk.
Factors not associated with early AMD included blood pressure, body mass index, physical activity level, history of heavy drinking, white blood cell count or total cholesterol level.
Drusen were present in the macula-the area in the retina responsible for sharp vision-in 63.3 percent of the participants, and the frequency of drusen increased with age.
When age was considered, men and women had approximately the same number of drusen.
The study has been reported in the June issue of Archives of Ophthalmology, one of the JAMA/Archives journals.