Eyes that do not produce the required amount of tears are called dry eyes. This is a disease caused when the tear production is decreased or when there is an increase in the tear film evaporation. There is an irritation caused due to this, the eyes have a burning and a dry sensation. These symptoms occur mainly when there is loss of water in the tears, which cause the tears to become more salty or hyper tonic.

A dry eye is one of the most common problems treated by eye physician. It is basically caused by a problem with the quality of the tear film that lubricates the eyes. Tears are comprised of three main layers:
1. The mucus layer: The mucus layer coats window, forming a foundation so the tear film can stick to the eye.
2. The middle aqueous layer: The middle aqueous layer provides moisture and supplies oxygen and other important nutrients to the cornea. This layer is made up of 98% water along with small amount of salt, proteins and other compounds.
3. The outer lipid layer: The outer lipid layer is an oily film that seals the tear film on the eye and helps to prevent evaporation.

Tears

Tears are formed in several glands around the eye.  The water layer is produced in the lacrimal gland, located under the upper eyelid.  Several smaller glands in the lids make the oil and mucus layers.  With each blink, the eyelids spread the tears over the eye.  Excess tears flow into two tiny drainage ducts in the corner of the eye by the nose.  These ducts lead to tiny canals that connect to the nasal passage.  The connection between the tear ducts and the nasal passage is the reason that crying causes a runny nose. Dry eye syndrome has many causes.  One of the most common reasons for dryness is simply the normal aging process.  As we grow older, our bodies produce less oil – 60% less at age 65 then at age 18.  This is more pronounced in women, who tend to have drier skin then men.  The oil deficiency also affects the tear film.  Without as much oil to seal the watery layer, the tear film evaporates much faster, leaving dry areas on the cornea.

Other factors

Many other factors, such as hot, dry or windy climates, high altitudes, air-conditioning and cigarette smoke also cause dry eyes.  Many people also find their eyes become irritated when reading or working on a computer.  Stopping periodically to rest and blink keeps the eyes more comfortable. Contact lens wearers may also suffer from dryness because the contacts absorb the tear film, causing proteins to form on the surface of the lens.  Medication such as oral contraceptives, anti depressants can contribute to the symptoms of dry eyes. Chemical burns can also cause this disease. There are various conditions that cause dryness, smoky and heaty room, hair dryers, exposure to wind; riding a bike also can cause the lenses to dry, thyroid conditions, vitamin A deficiency, and diseases such as Parkinson’s and Sjogren’s can also cause dryness.  Women frequently experience problems with dry eyes as they enter menopause because of hormonal changes.  
 
Dry eyes contact lenses:

Treatment:

People who experience the dry eye syndrome do not have a permanent cure but lenses and other medication like drops or ointment can lessen it. Usually these patients cannot tolerate lenses but a great amount of improvement has been done in the technology. They are now fitted with newest polymers; this allows the lenses to preserve water. This helps the person not feel the dryness. Restasis is a drop that allows these patients to wear the contact lenses for as long as eight hours. These are the only drops approved by the FDAto treat chronic eyes. Earlier people had no choice but to wear glasses, now they have to be thankful to the latest technology in contact lenses and also the multifocal lenses.

Types:

Lenses are of different types Soft, Hard and Semi Soft lenses. Depending on the patient the doctor will suggest which lenses should they opt for. Lenses are manufactured from two types of polymeric material. Soft lenses are made from hydrophilic plastic, which contains water. The more the water a soft lens contains the more it is prone to dehydrate and loss of water causing dryness. This is anyways a temporary problem. Changing the material of the lenses or changing the water content of the soft lenses can eliminate it. Many companies have come up with lenses to eliminate the dryness of eyes. Some of them are: Acuvue Advance, these are made of hydra clear solution. Being very soft and siklythey are very easy to use they have two designs in lenses. UVA&UVB.

Biomedics: These are to be disposed off in 2 weeks. They have a visibility tint, thus making it easier to remove and insert.
Focus Night and Day: These are perfect for people with hectic lifestyle. The main advantage is that it reduces the botheration of inserting and cleaning. Use it for a month and throw.