Tears bathe the eye to keep it moist and remove irritating particles. Clear vision depends on a healthy layer of tears covering the surface of the eye. When the eye cannot produce enough tears or produces abnormal tears, dryness is the result.
Tears have three major components:
- Oil outer layer. Produced by the meibomian glands that line the inner eyelid. This layer keeps the watery layer from evaporating.
- Water (aqueous) middle layer. Produced by the lacrimal gland and at a slow, steady rate or in quantities in response to eye irritation or emotion.
- Mucin inner layer. Produced by the conjunctiva. The mucus allows the watery layer to stick to the eye and spread evenly over the surface.
Dry eyes cause stinging, burning, a gritty sensation, stringy mucus production, intermittent blurred vision and excess tearing. If the tears that are supposed to maintain the correct lubrication of the eye are not effective, the resulting irritation will trigger the lacrimal glands to produce a large quantity of the watery component of tears (reflex tearing). These excess tears overwhelm the tear drainage mechanism and result in tears spilling over onto the cheeks.
Dry eye symptoms can manifest as irritation from smoking, exposure to wind or dashboard heaters, discomfort after short periods of reading or computer work, or with contact lens use. It is common for the symptoms to begin or become worse in the afternoon or evening.
Dry eyes are more common with age due to decreased tear production. This is particularly true of postmenopausal women and may be related to hormonal changes. People with an inflammatory eyelid condition called blepharitis often have associated dryness. Patients with certain autoimmune diseases like rheumatoid arthritis and lupus are at high risk for reduced tear production. Sjögren’s syndrome is a chronic autoimmune disease that causes dry eyes and dry mouth. Radiation treatments to the head can result in decreased tear production. The refractive procedure LASIK causes dry eyes because of damage to nerves in the eye.
A number of common medications can reduce tear production. These include diuretics (water pills) used for high blood pressure, heart failure, and chronic leg swelling; beta-blockers used for heart disease and high blood pressure; antihistamines used for allergies; birth control pills; some antidepressants; non-steroidal pain relievers; and isotretinoin, used to treat acne.
The Tear Lab Osmolarity System is an in-office test to determine the health of the tear film. It assists in making a diagnosis of dry eyes and is helpful in monitoring response to treatment over time. This painless test takes less than a minute to perform in our office.
For most people with mild or occasional dryness, over-the counter artificial tears used up to four times a day are effective to relieve the symptoms. Preservative-free tear drops are available for people who are sensitive to the preservatives or who need drops more than four times a day for relief. These drops can be safely used as often as needed. Ointments are very thick and tend to blur vision but are great to use at bedtime and can relieve irritation that is present on waking up. Warm compresses are also a very effective tool as they help boost the production of the outer oil layer of the tear film.
To minimize evaporation of tears, which tends to be worse in arid environments, use a humidifier. This is particularly helpful in the winter and when forced hot air heat is used. A pan of water can be set on a woodstove. Take periodic eye breaks when reading, working at the computer, or driving for long periods of time. Close your eyes for several seconds, then blink repeatedly for several seconds to redistribute the tears over the surface of your eyes. Keep your computer screen below your eye level.
Punctal plugs are small plastic devices that close off the tear drainage pathway, keeping the tears that are produced on the surface of the eye for a longer period of time.
Medicated eye drops may be needed to help boost your natural tear production and lower the amount of inflammation on the ocular surface from chronic dry eye. These medications are safe to use long term and are dosed easily twice daily.