|
|
Astigmatism is the most common vision problem. It may accompany nearsightedness or farsightedness. It is usually caused by an irregularly shaped cornea, but sometimes it is the result of an irregularly shaped lens. Either type can be corrected by eyeglasses, contact lenses, or refractive surgery.
There used to be a metric calendar, as well as metric clocks. The metric calendar, or "French Republican Calendar" divided the year into 12 months, but each month was divided into three 10-day weeks. Each day had 10 decimal hours. Each hour had 100 decimal minutes. Due to lack of popularity, the metric clocks and calendars were ended in 1795, three years after they had been first marketed.
Only one in 10 cancer deaths is caused by the primary tumor. The vast majority of cancer mortality is caused by cells breaking away from the main tumor and metastasizing to other parts of the body, such as the brain, bones, or liver.
Cytomegalovirus affects nearly the same amount of newborns every year as Down syndrome.
More than 50% of American adults have oral herpes, which is commonly known as "cold sores" or "fever blisters." The herpes virus can be active on the skin surface without showing any signs or causing any symptoms.
![Over nearly 30 years, humans removed many polar bears for a variety of reasons, from a population in](https://biology-forums.com/gallery/47/medium_33_22_09_11_9_39_28_18111448.jpeg)
![Arthroscopic surgery involves the surgery of a joint with the use of a flexible arthroscope and othe](https://biology-forums.com/gallery/47/medium_14755_24_09_12_7_49_32_89872018.jpeg)