If you have a hard time wearing contact lenses, or if your eyes are stinging and red, you might be the victim of Dry Eye.

Dry eyes are one of the most common complaints patients bring to their eye doctors. The nonprofit group - The National Women's Health Resource Center (NWHRC), estimates that 20.7 million Americans are affected by dry eye syndrome, and that symptoms of dry eyes account for one-fourth of all eye doctor office visits. Dry eyes can be the result of many situations from hormonal shifts to the surrounding environment.

"It's a common problem in people of all ages," says Dr. Andrew Caster, medical director of the Caster Eye Center in Beverly Hills, Calif. "It becomes more of a problem as we get older, and even more so among post-menopausal women."

For most of us, dry eye is a simple annoyance in our daily routine. However if  left untreated, dry eye syndrome can be debilitating condition. Symptoms include blurred vision, dryness, itching, irritation, and for some, the feeling of a foreign substance in the eye. Some patients report a  sensation of  sand, grittiness, while complain of their eyes feeling tired, achy or sore. People suffering from dry eye symptoms may experience difficultly, reading, driving at night, using contact lenses or working at the computer.

According to Dr. Michael Ehrenhaus, director of cornea and external disease and refractive surgery at Long Island College Hospital in Brooklyn, N.Y., dry eye is often misdiagnosed leading to a delay in receiving proper treatment.

Ehrenhaus goes on to state that dry eye syndrome frequently results in a decreased ability to produce ones own tears, or a problem with the actual tears themselves. The body produces tears to keep the eyes moist. Environmental conditions such as dryer air, living in a higher altitude, air conditioning, indoor heating, hormonal changes, aging, menopause,  vitamin deficiencies, thyroid problems, and diabetes, can all contribute to dry eyes.

According to NWHRC of 100 U.S. cities that are "Dry Eye Hot Spots." The number one hot spot on the list is Las Vegas, followed by four cities in Texas. The cities were ranked based on data archived by the National Oceanic & Atmospheric Administration's National Climatic Data Center and the Environmental Protection Agency. To rank the cities, researchers looked at factors known to aggravate dry eye symptoms: humidity, wind, altitude, pollutants and ocular allergens on a national, state and municipal level.