Eye dryness occurs when the surface of the eye does not have enough moisture. A dry eye feels scratchy, may sting, and vision may blur. Some people also experience excessive tearing, and even though this is the body’s natural response to dry eyes, the rush of tears washes away the soothing layers of the tear film, increasing eye dryness and irritation. Knowing some of the causes of eye dryness may help people with dry eyes find solutions to their dry eye problems.
Tear Film
Eyes have a tear film made up three layers that slow tear evaporation, coat the eye and offer moisture. An imbalance or low quality of one of these layers may cause eye dryness. Meibomian glands produce the oily layer of the tear film responsible for slowing evaporation, and lacrimal glands produce the water layer. If either of these glands clog, they cannot produce the right balance in tear film to adequately coat the eye’s surface. Infections or inflammation of the eyelids, such as blepharitis, may irritate the glands and cause eye dryness. Doctors usually treat these gland conditions with antibiotic or mild steroid eye drops.
Tear Production
As people age, the amount of tears they produce decreases, often causing severe dry eye symptoms. As well, conditions such as diabetes and rheumatoid arthritis may increase the likelihood of low tear production. Artificial tears may help relieve eye dryness, and for most people, using the drops long-term does not pose risks. Some eye drops contain preservatives, and if an artificial tear user has an allergy to these additives, they should only use preservative-free artificial tears. Some patients request prescription eye drops to help increase tear production; for some patients this treatment works well, while others find minimal changes to dry eyes.
Eyelids
Blinking helps replenish the tear film, spreading the film across the eye. If eyelids do not function well, the tear film will not distribute properly. Conditions such as ectropion causes the eyelids to turn outward at the lash line, as though the upper eyelid curls up and the lower lid curls down. Since the lids curl up, they often do not meet when the eyes are closed, causing disruption in the tear film. Entropion has the opposite effect, causing the eyelids to turn in. The eyelashes rub and scratch the surface of the eye. These conditions typically develop with age, though they do not occur in everyone. Artificial tears may provide temporary relief, but doctors can only correct these lid conditions with surgery.
Environment
Environmental conditions may cause decreased tear production or changes in tear film. Air conditioned homes and offices often circulate air, drying out the eyes. As well, extended computer use often results in infrequent blinking, causing eye dryness. Preventing eye dryness due to environmental conditions may include taking breaks when working on a computer for long periods of time, or pointing fans or vents away from a work area. Artificial tears will relieve stinging and other dry eye symptoms resulting from these situations.
