The eye depends on the flow of to provide constant moisture and lubrication to maintain vision and comfort. Tears are a combination of water, for moisture; oils, for lubrication; mucus, for even spreading; and antibodies and special proteins, for resistance to . These components are secreted by special located around the eye. When there is an imbalance in this tear system, a person may dry eyes.
When tears do not adequately lubricate the eye, a person may experience:
• Pain
• Light
• A gritty sensation
• A feeling of a foreign or sand in the eye
• Itching
• Redness
• Blurring of vision
Sometimes, a person with a dry eye will have excess tears running the cheeks, which may seem confusing. This happens when the eye isn't getting enough lubrication. The eye sends a distress signal through the nervous system for lubrication. In response, the eye is flooded with tears to try to compensate the underlying dryness. However, these tears are mostly water and do not have the lubricating qualities or the rich of normal tears. They will wash debris , but they will not coat the eye surface properly.
In to an imbalance in the tear-flow system of the eye, dry eyes can be caused by situations that dry out the tear film. This can be due to dry air from air , heat, or other environmental conditions. Other conditions that may cause dry eyes are:
• The natural aging , especially menopause
• Side of certain drugs such as antihistamines and birth pills
• Diseases that affect the to make tears, such as rheumatoid arthritis, and collagen vascular diseases
• Structural problems with the eyelids that don't allow them to close .