Causes of Dry Eyes

Causes of Dry Eyes

(Causes of Dry Eyes) Let’s take an in-depth look at the various medical conditions and medications that can cause dry eyes. As noted above, dry eyes are caused by one of two factors—either your tear system is not producing enough tears or the tears being produced are not keeping your eyes sufficiently moisturized. The tear system is complex: Tears carry nutrients to the cells on the surface of the cornea (the front surface of the eyeball) and remove dead or damaged corneal cells. Tears also keep debris away from the cornea, allowing light to enter the eye unimpeded—a necessity for clear vision. To function normally, the cornea must be covered at all times by a coating of tears called the tear film. Tears are made up of oil, water, and mucous. Here is a closer look at each layer of the tear film:

• The oily layer is the outermost layer. It is produced by the meibomian glands, which are found in the eyelids. The oily layer floats on top of the tear and acts to slow the evaporation of tears from the surface of the eye.

• The watery layer, or the middle layer, is a major part of the tear film. It is produced by the lacrimal glands, which are located in the upper outside portion of each eyeball socket. Tears originate from the outer part of the eye (toward the ear) and are wiped across toward the inner part (closer to the nose).

• The mucous layer, also known as the mucin, is the innermost layer, which is produced by cells in the conjunctiva and cornea. It is the layer that touches the eye and acts as a detergent that allows the tears to spread smoothly and evenly over the cornea.

Tears are mostly made of water, and are produced primarily by the lacrimal glands. The eyes produce three types of tears: basal tears, reflex tears, and emotional tears, any of which can trigger the lacrimal gland to secrete even more of the watery component. Here is a look at the different types of tears:

• Basal tears provide lubrication between the cornea and eyelid. They protect the eyes from dust, bacteria, viruses, fumes, and other foreign particles. Basal tears are the normal level of wetness that our eyes should have at all times.

• Reflex tears are the eyes’ response to strong fragrances or fumes, wind, or even spicy foods. Reflex tears are sent out like an army of troops, with the goal of washing or flushing away foreign substances.

• Emotional tears are the eyes’ response to strong emotion.

Certain foods can indirectly cause dry eyes. Chocolate, colas, coffee, and tea all contain caffeine, which robs your body of moisture. Try avoiding or limiting these foods and drinks.

Watery Eyes can also be a major problem. This may seem counterintuitive, but dry eyes cause a reactionary increase in tear secretion that causes “watery eyes”—and this increase in tear flow actually can make the dry eye worse! In other words, your eyes are dry and irritated. This irritation causes the eyes to feel as if there were foreign particles on them. This in turn causes the eyes to water in order to try to wash these foreign particles out.

Other causes of dry eyes include blockage of the tear ducts or medications that inhibit the production of tears. This problem often leads to chronic dry eyes, as the person is not able to manufacture tears and the eyes are not sufficiently lubricated. Tears evaporate rapidly, and the eyes are not cleaned properly.

Environmental factors can also play a role. Dusty air, dry or windy weather, or fumes like cigarette smoke can evaporate tears much speedily or hamper their effectiveness. This is especially a cause for dry eyes in contact lens wearers, as the lenses absorb lubrication. Contact lens wearers usually experience dry eyes because the contacts seem to dry out the eyes faster. Many contact-lens wearers regularly require rewetting drops.

Working or entertainment can also cause dry eyes. People who spend a lot of time watching TV or using a laptop may suffer eyestrain and dry eyes due to infrequent blinking. Dry eyes can also be caused by a vitamin A deficiency, by some medications, or by some diseases. Inadequate sleep can also cause dry eyes, as eyes that are not allowed to rest are apt to dry up faster.

SOURCE: http://www.eyehealthweb.com/dry-eyes/