What is Macular Degeneration?
Macular degeneration is an eye condition which affects the center of a person’s vision. This loss of vision is more common as one ages. It is the major cause of blindness in older adults.
Where is the Macula?
The macula is a specialized potion of the retina that is located right in the center of a person’s vision. The retina is the inside lining of the eye that acts like the film of a camera. The macula is in the center of the retina and this is the only part of the retina that has reading capable vision. When you need to see something clearly you have to directly look at it. You cannot read anything with your side vision. Therefore, macular degeneration causes loss of central vision. It can make it difficult or impossible for one to read, watch TV, drive a car, or recognize someone’s face depending on the severity of the macular damage. In most cases people retain their side vision and are able to perform routine daily activities. There are two types of macular degeneration.
Dry Macular Degeneration
Dry macular degeneration is a slow deterioration of the cells in the macula. Drusen may also be present, which are small yellowish deposits in the area just under the retinal layer. The exact cause of drusen is not known but their presence is an indication that the cells in the macula are at risk of developing macular degeneration. The risk is greater if the drusen are large and more numerous. As the cells in the macula slowly either die and atrophy or form scars the central vision gradually diminishes. Eighty five to ninety percent of macular degeneration cases are of the dry type. Dry macular degeneration has three stages.
Early Macular Degeneration
This is categorized by a few small or medium sized drusen. There are not usually any symptoms or blurred vision with this level.
Intermediate Macular Degeneration
This is categorized by more medium sized drusen and may have a few large drusen. There will be a beginning of alteration in the retinal cells in the macula. Atrophy of the retinal pigment epithelial cells and loss of the photoreceptors (rods and cones) leads to the loss of vision. Some people will be able to see a blurred area in their central vision.
Advanced Macular Degeneration (Central Geographic Atrophy)
This is categorized by extensive atrophy of the retinal pigment epithelial cells and photoreceptors. This leads to severe loss of central vision.
Wet Macular Degeneration
Neovascular or wet macular degeneration occurs when an abnormal blood vessel (choroidal neovascularization) in the choriocapillaris (layer under the retina) breaks through Bruch’s membrane to bleed into the retina. The bleeding leads to scarring in the macula that progresses to permanent damage to the cells in the macula.