What is Dry Eye Syndrome?
Dry Eye Syndrome is a condition affecting the tear system. While the term dry eyes may sound simple, it is actually quite complex. Dry eyes (keratoconjunctivitis sicca) are due to a problem with the quantity or quality of the tears in the eye, or sometimes a combination of both.
Symptoms, causes, and treatment options vary widely. It is estimated that one in every eight adults, or 33 million Americans, have some form of dry eye syndrome. People of both sexes and all ages can suffer from dry eyes. The condition can be mild or severe, with mild cases being more of a nuisance that is easily fixed with a drop of artificial tears, and severe cases causing poor vision that may require surgery.
As mentioned above, dry eyes are caused by one of two factors—either your tear system is not producing enough tears or the tears being produced are not keeping your eyes sufficiently moisturized. The tear system is pretty complex: Tears carry nutrients to the cells on the surface of the cornea (the front surface of the eyeball) and remove dead or damaged corneal cells. Tears also keep debris away from the cornea, allowing light to enter the eye unimpeded, a necessity for clear vision. To function normally, the cornea must be covered at all times by a coating of tears called the tear film. Tears are made up of oil, water, and mucous. Here is a closer look at each layer of the tear film:
- The oily layer is the outermost layer. It is produced by the meibomian glands, which are found in the eyelids. The oily layer slows the evaporation of basal or watery tears from the surface of the eye.
- The watery layer, or the middle layer, is a major part of the tear film. It is produced by the lacrimal glands, which are located in the upper outside portion of each eyeball socket. Tears originate from the outer part of the eye (toward the ear) and are wiped across toward the inner part (closer to the nose).
- The mucous layer, also known as the mucin, is the innermost layer, which is produced by cells in the cornea. It is the layer that touches the eye and acts as a detergent that allows the tears to spread smoothly and evenly over the cornea.
Tears are mostly made of water, and are produced by the lacrimal glands. The eyes produce three types of tears: basal tears, reflex tears, and emotional tears, any of which can trigger the lacrimal gland to secrete even more of the watery component. Here is a look at the different types of tears:
- Basal tears provide lubrication between the cornea and eyelid. They protect the eyes from dust, bacteria, viruses, fumes, and other foreign particles. Basal tears are the normal level of wetness that our eyes should have at all times.
- Reflex tears are the eyes’ response to strong fragrances or fumes, wind, or even spicy foods. Reflex tears are sent out like an army of troops, with the goal of washing or flushing away foreign substances.
- Emotional tears are the eyes’ response to strong emotion.
Dry Eye Symptoms
Dry eye symptoms may appear suddenly or gradually, and can last for hours or days. Although there is no cure for dry eye syndrome, there are things you can do to treat or relieve the symptoms. Common dry eye symptoms include:
- Eye pain
- Feeling of a foreign object in eye
- Eye fatigue
- Swollen eyes
- Excessive tearing (as a response to the brain sensing a “dry spot”)
- Itchy eyes
- Eyelid twitching
How Do Tears Prevent Dry Eyes?
As we have just learned, tears are a major protective agent for the eyes. Tears not only wash dust away from the eyes, but also soothe the eyes, provide oxygen and nutrients to the cornea, and help defend against eye infections by removing microorganisms that can colonize the eyes. So how do we prevent dry eyes? In some cases it may not be that simple. As we age, our tear system, like the rest of our body, begins to shut down. We simply do not produce as many tears as we once did, and the tears we do produce are not of high quality. It is possible, however, for younger people to mitigate this condition by taking preventive steps now, before the tear system begins to shut down.
Here are some general tips to help you prevent dry eyes:
- Avoid over-the-counter eye drops that contain preservatives.
- Blink more often.
- Increase your intake of vitamins A and C by making sure your diet consists of many green, leafy vegetables, fish, nuts, citrus fruits, and vegetables.
- Do not ignore symptoms of dry eye syndrome.
- Avoid windy and dusty environments; do not allow air to blow directly into your eyes, as can happen when using a hair dryer.
- Use a humidifier during winter months, or whenever you are in a dry indoor environment.
- Take “eye breaks” if you are going to be reading or staring at a computer for a long time. A handy rule to remember is to gently close your eyes for twenty seconds every twenty minutes that are spent looking at a video display or reading material.
- Using warm, moist compress therapy on your eyes daily will help to keep the oily meibomian glands from becoming clogged.
- Practice good eyelid and eyelash hygiene. Use commercially available pre-moistened eyelid cleansers or a mild baby shampoo to keep your eyelashes and meibomian glands clean.
- Protect your eyes from UV rays, chemicals, radiation, and wind by wearing sunglasses, goggles, or a face mask.
- Position computer screens below eye level to allow your eyelids to cover more of your eyes instead of keeping them wide open, as they are when you are looking up.
- Avoid artificial sweeteners.
- Drink plenty of water each day to avoid dehydration.
- Avoid foods that contain transfatty acids, such as margarine.
Dry Eye Syndrome Facts and Statistics
Here are some interesting facts and statistics about dry eye syndrome:
- Dry eye syndrome is primarily a dysfunction of basal tears, as most dry eye sufferers still have normal reflex and emotional tearing.
- Approximately 33 million Americans suffer from dry eye syndrome.
- Approximately 89 percent of the American popular is unfamiliar with the condition.
- Dry eye syndrome is considered the most common eye problem.
- Vitamin B3 may cause dry eyes.
- You blink an average of twenty times per minute.
- Almost 10 percent of post-menopausal women suffer from dry eyes.
- There is no cure for dry eye syndrome, only effective treatment options.
- Women are twice as likely as men to develop dry eyes.
- Estrogen supplements may increase the risk of dry eye by age 70.
- Estrogen and progesterone supplements together increase the risk of dry eye by 30 percent.
- Homeopathic remedies—which have never been proven to treat any medical condition—may have a negative impact on eyes that are already dry; examples of homeopathic remedies include aconite 6c and alumina 6c, both of which are said to alleviate dryness.
- Eye make-up can thin the oily layer of the tear film..
- J. Weizer, MD; J. Stein, MD, MS “Reader’s Digest Guide to Eye Care” (Quantum Publishing, Ltd. 2009) 104-107
- J. Anshel, MD “Smart Medicine for Your Eyes” (SquareOne Publishers, 2011) 209-214
- J. DiGirolamo, MD “The Big Book of Family Eye Care” (Basic Health Publications, Inc. 2011) 117-127