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A cataract is a clouding of the eyes' natural lens. As we age, some clouding of the lens may occur. The first sign of a cataract is usually blurry vision. Although glasses and other visual aids may at first help a person with cataracts, surgery may become inevitable. Cataract surgery is very successful in restoring vision, and it is the most frequently performed surgery in the United States.
Asthma cases in Americans are about 75% higher today than they were in 1980.
Sildenafil (Viagra®) has two actions that may be of consequence in patients with heart disease. It can lower the blood pressure, and it can interact with nitrates. It should never be used in patients who are taking nitrates.
Most childhood vaccines are 90–99% effective in preventing disease. Side effects are rarely serious.
After a vasectomy, it takes about 12 ejaculations to clear out sperm that were already beyond the blocked area.