from Ophthalmology September 2008 Sunness et al.
Geographic atrophy is the advanced dry, or atrophic, form of AMD. This is present in 2% of people 75 to 84 years of age and 7.3% of people 85 or over and 20% of people 90 or over. It progresses gradually and can be responsible for both moderate and severe visual loss.
If the centre of the macula (the fovea) is affected, then vision on the Snellen visual acuity chart will be affected. In many people, the condition starts slightly off-centre, so that apparent vision is quite good, although in practice reading and face recognition may be affected. Unfortunately, patients with extrafoveal invovlment have a high risk of visual acuity loss in the future. These patients also have poor vision in dim lighting which can be tested by measuring visual acuity with and without a 2.0 log unit neutral density filter and this can be used to predict future detioration in subjects with good visual acuities. Unfortunately, apart from vitamin combinations and zinc, there is currently little specific treatment for this condition.