Geographic atrophy

The prevalence of GA increases with age, being half as common as CNV at age 75, and more common than CNV in older age groups. GA continues to enlarge over time with a median rate of enlargement over a 2-year period of 1.8 MPS disk areas. Scotomas from GA, the advanced form of nonneovascular AMD, involve the parafoveal and perifoveal retina early in the course of the disease, sparing the foveal center until late in the course of the disease. These parafoveal and perifoveal scotomas compromise the ability to read and to recognize faces, often despite the retention of good visual acuity, accounting for a large percentage of moderate visual loss in those affected. Hemorrhage may occur in eyes with GA in the absence of CNV. Small areas of CNV that can be associated with hemorrhage may be transient, becoming clinically inapparent, or appearing as increased atrophy, a few months later. There is a higher incidence of CNV in eyes with GA at baseline that have fellow eyes with CNV. GA is bilateral in more than half of the people with this condition. The size and rate of progression of atrophy are highly correlated between the two eyes of patients with bilateral GA, but the acuities may differ due to central sparing. Among eyes with GA with visual acuity better than 20/50, there is a 40% rate of three-line visual loss at 2 years. Maximum reading rate can be significantly affected by encroachment of GA on the fovea, even while there may still be little change in visual acuity. Eyes with GA have marked loss of vision in dim environments and benefit greatly from increased lighting. The development of a preferred retinal locus (PRL) can aid in the effective utilization of the remaining functional retina.