Their possible role in photoreceptor rescue or degeneration is unknown. Furthermore, it has been found that mononuclear phagocytes are seen in abundance in the subretinal space in eyes with GA. In donor eyes with GA, choroidal T-lymphocytes and macrophages are noted to produce proinflammatory cytokines. Oxidative stress and low grade inflammation seem to play a role in AMD. This has been suggested to be a systemic immune-dysfunction, with retinal manifestation. Drusen are shown to contain multiple complement components, indicating that localized inflammation mediated by the complement system is an important element in AMD. Complement factor H variant Y402H and ARMS2 have been associated with increased risk of GA development. Genetic and environmental factors seems to contribute substantially. The cause of GA is not fully known, though it has been studied extensively. Individuals with GA are at a high risk of developing choroidal neovascularizations, and patients with exudative AMD are at an increased risk of developing atrophic areas. Clinically, the exudative and non-exudative AMD are very different, but these late stages of AMD are not mutually exclusive. As the atrophic area expands, visual function decreases. Reticular pseudodrusen are associated with the development of GA The progression rate of GA varies, but is relatively slow and progresses over years. The defect in structures allows the observer to see the larger underlying choroidal vessels. GA is recognized as a sharply defined area in the posterior pole, with atrophy of the retinal pigment epithelium, the overlying photoreceptors and the choriocapillaris. Late stages of AMD is either characterized by choroidal neovascularization, or GA. The natural course of AMD begins with early stages that are characterized by presence of drusen that are yellow deposits between the retinal pigment epithelium and Bruch’s membrane. 3 One of the strongest risk factors was poor visual acuity at baseline, specifically visual acuity at or worse than 20/200 had almost a 3-fold risk of developing GA than those with a baseline of 20/25-20/40. They also found that thicker subretinal tissue complex and presence of subretinal fluid were associated with slower development of GA. The Comparison of Age-Related Macular Degeneration Treatments Trial (CATT) found that older age, hypercholesterolemia, worse visual acuity, larger choroidal neovascularization (CNV) area, retinal angiomatous proliferation (RAP) lesion, GA in the fellow eye, and intraretinal fluid were associated with a higher risk of incident GA. Other studies have pointed out an increase in risk of GA in patients with coronary heart disease as well as in patients with lens opacities or previous cataract surgery. People with higher education were at a lower risk of GA. The Age-Related Eye Disease Study also found an increased risk of GA in users of thyroid hormones or antacids. Studies focusing on the United States have not found any gender difference in the prevalence of geographic atrophy, but the Asian Eye Epidemiology Consortium found a higher prevalence of GA in men. This study also showed that the ratio of GA to neovascular AMD, another complication of advanced AMD, in the Asian population is lower (1:3) compared to that of the European population (1:1). One retrospective study through the Asian Eye Epidemiology Consortium found that GA is relatively uncommon in Asian populations when compared with those of European Ancestry. Both active smokers, but also former smokers are at greater risk of developing geographic atrophy. Smoking history increases the risk of GA significantly. The most pronounced risk factor is increasing age and family history of AMD. Several risk factors have been noted by several studies. The incidence of GA is expected to rise as the age-burden of developed countries is increasing. Over 8 million people are affected worldwide with GA, approximately 20% of all individuals with AMD. It starts typically in the perifoveal region and expands to involve the fovea with time, leading to central scotomas and permanent loss of visual acuity. The disease is characterized by localized sharply demarcated atrophy of outer retinal tissue, retinal pigment epithelium and choriocapillaris. Geographic atrophy (GA) is a chronic progressive degeneration of the macula, as part of late-stage age-related macular degeneration (AMD).
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