Dry eye syndrome (or dry eyes) is a chronic reduction in the normal amount or quality of tears, causing insufficient lubrication of the eye.  It can cause mild to severe discomfort and damage to the tissues of the surface of the eye - the cornea and conjunctiva.

What are the symptoms of dry eye syndrome?

Symptoms of dry eye syndrome include:

What causes dry eye syndrome?

The normal tear film of the eye has three components:

Water

Most of our tear film is composed of a watery substance, secreted by the lacrimal glands, located above and behind our upper eyelids.  This watery (or aqueous) component of our tears nourishes and cleans the cornea and other tissues on the front of the eye.

Oils

Oils secreted from Meibomian glands (located at the margins of our eyelids) help keep our tears from evaporating too quickly.

Mucin

Mucin is a mucous-like substance that is produced by cells in the conjunctiva and outer surface of the eye.  It helps tears spread more easily across the cornea.

A deficiency in the quantity or quality of any of these three components of the tear film can cause dry eye syndrome.

The most common cause of dry eye is a deficiency in the watery component of tears - also called aqueous tear deficiency (ATD).  Keratoconjunctivitis sicca (KCS) is the medical term used to describe dry eye syndrome resulting from ATD.

Who is at risk of dry eye syndrome?

Risk factors for dry eye syndrome include:

How common is dry eye syndrome?

Dry eye is a very common disorder that affects a significant percentage of the population - especially people over age 40.  Studies vary in their estimations of this percentage, but at least one survey suggests that approximately 20 percent of people in the United States suffer from dry eye syndrome.¹  Some researchers believe 75 percent of the population over age 65 experiences dry eye symptoms.

How is dry eye syndrome diagnosed?

If you suspect you have dry eyes, you should make an appointment to see your eye doctor.  Heor she will ask you a number of questions about your symptoms andhealth history and perform one or more diagnostic tests to determine ifyou have dry eye syndrome.

One common diagnostic test is called the Schirmer test.  It is performed by placing a thin strip of filter paper under your lower eyelid.  Ananesthetic eye drop may or may not be used prior to positioning thepaper strip. You will then be asked to keep your eyes closed for fiveminutes.  The amount of wetting of the paperstrip is then measured to determine how well your lacrimal glands canproduce the aqueous component of your tears. 

Another common diagnostic test for dry eye is called the Tear Break-Up Test (TBUT).  It is performed by placing a small amount of a fluorescent dye in your tear film.  Your eye doctor will then examine your eyes with a blue light.  The dye mixes with your tears and causes the tear film on your eyes to glow under the examination light.  You will be asked to blink several times and then keep your eyes open as long as you can without blinking.  Yourdoctor will measure how long it takes for dark spots to appear on yourcornea, indicating that the tear film has broken up and the surface ofyour eye has become dry at those spots.  A tear break-up time of less than 10 seconds suggests an unstable tear film and dry eyes.

Youreye doctor may perform other tests in place of (or in addition to) theSchirmer test and/or Tear Break-Up Time test to determine whether ornot you have dry eye syndrome.      

How is dry eye syndrome treated?

There are a number of ways to treat dry eyes.  The treatment your eye doctor chooses for you will depend on the type and severity of your condition.

Artificial Tears

Mild cases of dry eye syndrome can be treated with non-prescription artificial tears.  Thereare many brands and formulations to choose from, includingpreservative-free products in single-dose packaging for people withsensitive eyes.  Your eye doctor will recommend one or more brands for you to try.

Lubricating Ointments

Insome cases, your eye doctor will recommend that you supplement daytimeuse of artificial tears with bedtime use of a lubricating ointment.  If so, you will be instructed to put about a half-inch application of the ointment inside your lower lid.  Your body heat will melt the ointment and your lids will spread it across your eye when you blink.  Ointments stay on your eyes much longer than artificial tears, but they will blur your vision.  For this reason, ointments should be used only at bedtime.

Medicated Eye Drops 

In some cases, dry eye syndrome may be due to inflammation.  There is now a prescription eye drop (called Restasis (R)) designed to treat inflammatory dry eye and increase your body's ability to produce tears.  Ask your eye doctor if Restasis (R) therapy might be able to increase your tear production and effectively treat your dry eye condition.

Punctal Occlusion

For more significant dry eye problems, your eye doctor may recommend a procedure called punctal occlusion.  This procedure keeps more tears on your eyes by blocking the ducts in your lids that drain tears away from your eyes.  Punctalocclusion involves inserting small plugs in the openings (puncta) ofthe tear drainage ducts that are located on the inner surface of eacheyelid, near the nose.  The plugs may be temporary (made of collagen that dissolves in a week or two) or permanent (made of silicone).  If necessary the permanent plugs can be removed later.  The procedure is painless and takes only a few minutes.  Punctal occlusion may eliminate or significantly reduce your need for artificial tears.  Ask your eye doctor for details.

Nutritional Therapy

There is growing evidence that supplements of omega-3 fatty acids may be effective in treating some cases of dry eyes.  Omega-3s are essential fatty acids - meaning that because our body cannot produce them, they are a required part of a healthy diet. 

Most Americans don't consume enough omega-3's. It's been estimated that 83% of people in the U.S. are deficient in this essential nutrient.^2,3

Some research shows that the risk for dry eye decreases with increased dietary intake of omega-3s⁴.  Other research shows that omega-3 supplements may have a positive effect onthe Meibomian glands in your lids that secrete the oils that reducetear evaporation.⁵

Becauseof these and other studies, some eye doctors recommend that their patients with symptoms of dry eye increase their daily intake ofomega-3 fatty acids.  The two best natural sources of omega-3s are dark, oily cold-water fish (e.g. salmon) and flaxseed.  Omega-3s are also available in supplement form.  Ask your eye doctor for details.  

How can I reduce my risk of dry eye syndrome?

To reduce your risk of dry eyes, take the following precautions:

1.      Keep your body well hydrated.  Drink at least eight large glasses of water every day.

2.      Avoid alcohol and caffeine.  They have a dehydrating effect.

3.      Run a humidifier in your home for during winter or if you live in a dry climate.

4.      Moisten your contact lenses routinely with rewetting drops. 

5.      Clean your contact lenses daily and replace them as directed.

6.      Wear close-fitting sunglasses when outdoors (particularly on windy days).

7.      Eat salmon once a week or consider taking a daily supplement of omega-3 fatty acids.

Notes

¹EagleVision-Yankelovich Partners Survey, 1997.

²Simopoulos AP. Omega-3 fatty acids in health and disease and in growth and development. Am J Clin Nutr 1991;54:438-463.

³James MJ. Dietary polyunsaturated fatty acids and inflammatory mediator production. Am J Clin Nutr 2000;71(suppl):343S-8S.

⁴TrivediKA, Dana MR, Gilbard JP, Buring JE, Schaumberg DA. Dietary omega-3fatty acid intake and risk of clinically diagnosed dry eye syndrome inwomen. ARVO, 2003.

⁵Boerner CF. Dry eye successfully treated with oral flaxseed oil. Ocular Surgery News, October 15, 2000, p147-148.

Additional References

Gilbard JP. How an Omega-3 Supplement Treats Dry Eye. http://www.theratears.com/nutrition.htm.

Ekong AS. Dry Eye Syndrome. http://www.emedicine.com/oph/topic597.htm.