Macular degeneration is fairly common among the elderly. The macula is the portion of the retina responsible for clear, sharp, central vision. Occasionally, the waste products of some of the cells in the macula are not removed as they normally are. Instead, they just clump together, so that when you look directly at an object, you can’t see it clearly.
It’s as though you had a piece of dirt on a camera film. Light just can’t reach the film through the dirt to give a clear picture. However, your side (peripheral) vision is not affected. It doesn’t matter how strong a lens we put in front of these eyes. If the light can’t reach the macula, you’re not going to see what you’re looking at very clearly.
So, if you see a dark spot in the center of your visual field, it would be wise to have a thorough eye examination. If caught early enough, those dead cells in the macula can be treated with a laser beam and vision often improved.