A cataract is a clouding of the natural lens of the eye. The lens of the eye helps to focus, or direct, images from the front of the eye onto the retina. It must be clear and free of opacities or abnormalities in order to focus the images clearly on the retina. The retina then takes these images and transmits signals to the brain. Some of the symptoms of macular degeneration and cataracts overlap. Blurred vision can be due to either problem; however, age-related macular degeneration is more likely to cause distorted or wavy vision.
Cataracts, on the other hand, are more likely to cause problems with glare and significant blurring or double vision. Glare can be recognized when driving at night (you may have increased difficulty ignoring oncoming head-lights) or even during the day with bright sunlight. While all of us are sensitive to varying degrees of bright lights, cataracts result in a scattering of the light, which makes it even more difficult to see. Double vision is also a symptom of cataracts, or of some form of opacity in front of the retina, but is not a symptom of problems with the retina and therefore not a symptom of macular degeneration.