The tear film that coats the front of the eye is very complex. The outer layer of the tear film is oily, produced by special glands within the eyelid, and it serves to prevent evaporation of the salt water middle layer. The inner layer is made of mucus secreted from cells on the front surface of the eye and is important in helping the salt water layer spread across the front of the eye. The middle layer of salt water contains special anti-infective cells to prevent infections, but also collects the dust and debris that the tears are exposed to as they face the air.
The eyelids have a normal blinking rate of about fifteen blinks per minute. Blinking spreads the tears across the front of the eye while also causing excess tears to be pushed out of a drainage system that leads from the inner corner of the eyelids into the nose. Anything that causes disruption of blinking, such as staring at a computer, or wind or blowing fans, can compromise the tears.
Dry eyes can also result from medications like antihistamines and antidepressants, and medical conditions including arthritis or menopause. In some cases, poor tear quality and reduced tear quality have no specific causes and are simply due to the aging process.
Dry eyes can range from a truly dry eye surface to a very disrupted tear film. The person suffering from dry eyes might actually experience excessive tearing or eye watering as the tear gland tries to resolve the dry eye condition. When the tear levels are low, the eye senses burning and grittiness. Itching and discomfort can also be signs of dry eyes. As the condition worsens, the eyes can become continually red and vision can become blurry. Contact lenses may become coated with mucus, disallowing the contact lens wearer from wearing them for long periods of time.
Dry eyes can be diagnosed with special eye tests done by the eye doctor. Treatments for dry eyes range from simple artificial tear drops or ointments to special tear drainage plugs that keep the natural tears on the eye. In some cases dry eye can be treated with oral supplements containing Omega-3 fatty acids and in others it can be treated with a prescription eyedrop that stimulates tear production.
Your eye doctor should be made fully aware of any dry eye symptoms to maintain the long-term health and vision of your eyes.