When one blinks, a film of tears spreads over the eye, making the surface of the eye smooth and clear. Without this tear film, good vision would not be possible.
Sometimes people don't produce enough tears or the right quality of tears to keep their eyes healthy and comfortable. This condition is known as Dry Eye.
The tear film consists of three layers: an oily layer; a watery layer; a layer of mucus.
Each layer has its own purpose. The oily layer, produced by the Meibomian glands, forms the outermost surface of the tear film. Its main purpose is to smooth the tear surface and reduce evaporation of tears.
The middle watery layer makes up most of what we ordinarily think of as tears. This layer, produced by the Lacrimal glands in the eyelids, cleanses the eye and washes away foreign particles or irritants.
The inner layer consists of mucus produced by the conjunctiva. Mucus allows the watery layer to spread evenly over the surface of the eye and helps the eye remain moist. Without mucus, tears would not stick to the eye.
Normally, the eye constantly bathes itself in tears. By producing tears at a slow and steady rate, the eye stays moist and comfortable.
The eye uses two different methods to produce tears. It can make tears at a slow, steady rate to maintain normal eye lubrication. It can also produce a lot of tears in response to eye irritation or emotion. When a foreign body or dryness irritates the eye, or when a person cries, excessive tearing occurs.
It may not sound logical that Dry Eye would cause excess tearing, but think of it as the eye's response to discomfort. If the tears responsible for maintaining lubrication do not keep the eye wet enough, the eye becomes irritated. Eye irritation prompts the gland that makes tears (called the Lacrimal Gland) to release a large volume of tears, overwhelming the tear drainage system. These excess tears then overflow from your eye.
What causes Dry Eye?
The majority of people over the age of 65 experience some symptoms of Dry Eyes.
The development of Dry Eyes can have many causes. They include:
Age—Dry Eye is a part of the natural aging process. The majority of people over age 65 experience some symptoms of dry eyes.
Gender—women are more likely to develop Dry Eyes due to hormonal changes caused by pregnancy, the use of oral contraceptives, and menopause.
Medications—certain medicines, including antihistamines, decongestants, blood pressure medications and antidepressants, can reduce the amount of tears produced in the eyes.
Medical conditions—persons with Rheumatoid Arthritis, Diabetes and Thyroid problems are more likely to have symptoms of Dry Eye. Also, problems with inflammation of the eyelids (Blepharitis), inflammation of the surfaces of the eye, or the inward or outward turning of eyelids can cause Dry Eyes to develop.
Environmental conditions—exposure to smoke, wind and dry climates can increase tear evaporation resulting in Dry Eye symptoms. Failure to blink regularly, such as when staring at a computer screen for long periods of time, can also contribute to drying of the eyes.
Other factors—long term use of contact lenses can be a factor in the development of Dry Eye. Refractive Eye Surgeries, such as LASIK, can cause decreased tear production and dry out the eyes.
People with Dry Eye may experience symptoms of irritated, gritty, scratchy, or burning eyes, a feeling of something in their eyes, excess watering, and blurred vision. Advanced Dry Eye may damage the front surface of the eye and impair vision.
Treatments for Dry Eye aim to restore or maintain the normal amount or quality of tears in the eye to minimize dryness and related discomfort and to maintain eye health.