Age-related macular degeneration

Age-related macular degeneration damages the center of the retina, the layer at the back of the eye that turns light into signals. That center is called the fovea. Think of a photograph: the damage lands right in the middle of the photo, not at the edges. Macular degeneration is the leading cause of blindness in developed countries.

Down below, in the retinal pigment epithelium, the layer of cells that supports and cleans up after the photoreceptors, lipofuscin gradually builds up. Lipofuscin is a kind of cellular garbage. Beneath that layer, deposits called drusen collect, and over time photoreceptors, the cells that capture light, are lost.

There are two forms. In the dry form, also called non-neovascular, if vision is lost in the early and intermediate stages, it happens little by little rather than all at once. In the wet or neovascular form, what shows up is a choroidal neovascular membrane, meaning new vessels growing in from the choroid, the layer of vessels that sits under the retina.