|
Author Question: Since 2000, there has been a shift in how people watch television because of? A. the spread of ... (Read 27 times) |
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.
When blood is exposed to air, it clots. Heparin allows the blood to come in direct contact with air without clotting.
There are over 65,000 known species of protozoa. About 10,000 species are parasitic.
There are more nerve cells in one human brain than there are stars in the Milky Way.
Most childhood vaccines are 90–99% effective in preventing disease. Side effects are rarely serious.