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What happens to the eye?Age-related macular degeneration (AMD) is a disease of ageing ocular tissues in particular the retinal pigment epithelium (RPE).
The Retinal Pigment Epithelium (RPE) provides essential metabolic support to the retina through daily phagocytosis (removal) of rod outer segments and ensuing lipid metabolism, water/molecule transport, retinoid recycling/storage, maintaining the blood-retinal barrier, detoxification, and secretion of trophic factors.
AMD is classified into either a dry, atrophic type, or wet, exudative type. In both forms of AMD, there is damage and progressive loss of sub-macular RPE cells. In the dry form, there is a slow progressive decline in visual function as the RPE layer and the overlying macula atrophy. In the wet form, stiffened Bruch’s membrane easily becomes fractured and a combination of inflammatory and angiogenic factors are released which lead to blood vessels growing into the retinal nerve layer (Neovascular membrane). The neovascular membrane will quickly leak fluid, cause bleeding or both, which further depletes RPE and degrades central vision rapidly.
In both forms of AMD, loss of the supporting RPE layer results in photoreceptor death, and visual deterioration. The course of events tends to be more rapid and aggressive in the wet form of AMD than the dry form.