Cataracts are vision problems in which there is a clouding of the lens of the eye. While there are several types of cataracts, age-related cataracts are the most common form of the condition. Cataracts are very common in older people -- in fact, by age 80, more than half of all Americans either have a cataract or have had cataract surgery. Symptoms of cataracts include blurry vision, double vision, and frequent prescription changes for eyeglasses or contact lenses. A cataract can occur in either or both eyes, but it cannot spread from one eye to the other. In most cases, the only available treatment for cataracts involves surgery. Cataract surgery is one of the most common surgeries performed in the United States, with over 1 million cataract surgeries performed every year.