The key word in the name of this disease, Age-related Macular Degeneration (AMD), is macula, because this is the part of the eye that becomes damaged in this disease.

First you need a little background on the structure of the eye before you can understand the macula. As you read this page, it might help you to glance over at the Figure from time to time.

A ray of light entering the eye passes through many layers of the eye. In the front of the eye are the cornea (clear layer on the outside front of the eye) and the lens. In the interior of the eye is the vitreous, a jelly-like material. In the back of the eye (called the fundus) are the retina, retinal pigment epithelium, Bruch’s membrane, choroid, and sclera. Actually the sclera surrounds most of the eyeball and is the white part of the eye that we easily notice when we look at someone.

The cornea and lens focus images (the rays of light) entering the eye on the retina in the back of the eye. The retina contains about 120 million nerve cells, which together act as a light-sensitive film that transmits information about the image to the brain.

The photoreceptors are on the side of the retina closest to the sclera, and light shines through the other retinal layers to reach them. There are two kinds of photoreceptors; the cones are sensitive to bright light and color, and the rods are sensitive to dim light.

The picture at the left shows a greatly enlarged view of the cells and layers of the retina that are directly affected by AMD. To help you get oriented when you view this picture, in this picture light enters the eye from above, and the sclera (white of the eye) is off the bottom of this picture. The layers of the retina that are hurt by AMD are the photoreceptors, the retinal pigment epithelium (RPE), Bruch's membrane, and the choriocapillaris. The white lines at the left of the picture show point to each layer.

The retinal pigment epithelium is a flat layer of pigmented cells that care for photoreceptors in several important ways, including delivering vitamin A and removing waste products. (All cells have waste products as part of their normal functioning.)

Bruch’s membrane is a thin flat vessel wall between the retinal pigment epithelium and the choroid.

The choroid is a dense network of capillaries that supply nutrients (“food”) and oxygen to the retinal pigment epithelium and photoreceptors. The photoreceptors must have adequate levels of nutrients and oxygen in order to live and function properly so vision is good.

Now finally we’re at the point where we can tell you what the macula is. The macula is the part of the retina that allows you to see the central 20 degrees of the visual field. When you look straight ahead, your point of fixation and the area immediately around it is your central vision. The macular area of the visual field is about 20 inches across at an arm’s length. In the center of the macula is the fovea. The fovea is enriched with cone photoreceptors that are used for reading and other activities requiring detailed vision like threading a needle.

The layers of the macula that are impacted by AMD are the photoreceptors, the retinal pigment epithelium (RPE), Bruch’s membrane, and choroid.