GA Risk Factors and Progression

Risk Factors

The pathophysiological mechanisms leading to the development of AMD and subsequent progression to late-AMD are not fully understood. It is generally thought that GA is caused by a complex interaction of metabolic, genetic and environmental factors.¹³ Several risk factors (age, smoking, ethnicity and genetics) have been strongly associated with the development of GA, most of which are also risk factors for other forms of AMD.

Progression to late-AMD (GA & Neovascular AMD)

Progression from early- to late- AMD (GA and/or neovascular AMD) is a complex process. Some people progress quickly to late- AMD (either GA or neovascular AMD), whereas others may progress slowly over several years.¹⁴ The underlying mechanisms that cause an eye to develop GA versus neovascular AMD are not fully understood. No reliable genetic or environmental risk factors have been identified to predict whether a patient will develop one form or the other.¹⁵ Both types can occur simultaneously in the same eye, or simultaneously in different eyes; it has in fact been suggested that GA and neovascular AMD are not mutually exclusive diseases, but that they lie on the same disease continuum.¹⁶ Eyes developing both types may in fact be at a more advanced stage than either GA or neovascular AMD alone.

Factors affecting GA progression rates

Once GA has been diagnosed, the rate of progression varies between individuals. Mean growth rates of atrophic areas ranging from 1.2 to 2.8 mm² per year have been reported.^17,18 Factors associated with variations in GA growth rates include size, configuration and location of atrophic areas,^19,20,21 fellow eye status,²² genetic factors,²³ smoking, diet and sun exposure.