What is Dry Eye Disease?
The function of your eye can be compared to a camera. Just as a camera focuses light rays onto film to record a picture, the cornea and lens focus light onto your retina to form an image. While the lens is extremely important in the proper focusing of light rays, the front surface of the cornea is actually responsible for two-thirds of the total focusing power of your eye. Your tear film is present on the front of your cornea and provides the smooth, clear surface required for good visual function. In addition, the tear film provides lubrication for eyelid movement over the cornea, nutrition for the external surface of your eye, and also anti-bacterial substances to maintain the health of your eye.
The Tear Film Layers
The tear film is more than just salt water. It is composed of three layers—oil, water and mucous. Dry eye disease is an irritating and occasionally painful condition involving a reduction of (or imbalance between) one or more of the following three tear film layers.
Oil (outermost layer): is secreted by glands present near the base of the eyelashes to stabilize and retard evaporation of the tear film.
Water (middle/largest layer): is produced by the tear glands to provide lubrication and wash away debris. It contains oxygen, sugar and protein to nourish the cornea as well as antibodies and enzymes to help prevent infection.
Mucous or Mucin (innermost layer): is made by special cells in the conjunctiva (the thin, delicate membrane that covers the white part of your eye) to help the water layer adhere to the eye.
How Serious Is Dry Eye Disease?
For most people, it is uncomfortable but not vision-threatening. In some cases, however, a faulty or diminished tear film can affect the cornea's focusing ability and increase the risk of infection.
How Common Are Dry Eyes?
Dry scratchy, irritated eyes are a very common problem that affects all ages, especially older adults. It is hard to determine the exact number of dry eye disease sufferers because of the wide range of causes; however, it is known that at least 60 million people worldwide use artificial tear products to treat dry eye symptoms.
What Causes Dry Eyes?
An age-related, natural decrease in tear production: is the most frequent cause of dry eyes. In fact, tear volume decreases by up to 80 percent by age 70. This condition is called "keratoconjunctivitis sicca" and the majority of cases occur in women over age 40.
Autoimmune diseases: like rheumatoid arthritis, lupus, scleroderma, and Sjorgen's syndrome.
Skin problems: such as psoriasis, seborrheic dermatitis and ichthyosis.
Abnormality of the oil layer of the tear film: usually caused by chronic blepharitis (inflammation of the lid margin), which affects the glands that produce the oil layer.
Inflammation and scarring of the eye: resulting from radiation and chemical burns or diseases, such as sarcoidosis, Stevens-Johnson syndrome, pemphigoid and trachoma.
Medications: for treating high blood pressure, water retention, acne, colds, allergies, muscle aches and depression; as well as some types of eye drops.
Neurological diseases: that affect blinking ability, like Parkinson's.
Improper eyelid position/closure: caused by aging changes of the eyelid; Bell's palsy; thyroid eye disease; and nerve damage from infections, injury or tumors.
Environmental and physical factors: allergens, smoke, heating, air conditioning, contact lenses, etc.
Hormone changes: changes in estrogen, progesterone, or testosterone levels due to birth control, pregnancy, menopause, and hormone replacement therapy can affect tear film oil production and evaporation levels.
Meibomian gland dysfunction (MGD): blockage of the glands that produce the oil layer of the tear film.
Dry eye disease is a frustrating problem that usually affects both eyes and can range from a mild annoyance to severe discomfort. If you are significantly bothered by one or more of the following symptoms, you should arrange for an evaluation of your condition:
Redness, itching and/or burning
A gritty or sandy sensation
Feeling a "film" over your eyes
Increased irritation from smoke, fumes, air conditioning, drafts and low humidity
Less tolerance for contact lenses
Mucous strands/eyelid crusting
Discomfort after reading or computer work
Watery eyes (your body is actually producing more tears to try to soothe your eyes, but they quickly evaporate or run off.)
Detection & Monitoring
A medical history and detailed description of your symptoms is essential to properly diagnosing dry eye disease. Your eye care specialist will also conduct a thorough eye examination, including one or more of the following tests:
Schirmer's Tear Strips: After numbing your eyes with drops, these small paper strips measure the amount of tears your eyes produce.
Rose Bengal Staining: These rose-colored drops are used to highlight areas on the front of your eye that are dry and irritated.
Fluorescein Staining: These yellow-colored drops reveal areas where the cornea (the transparent front portion of the eye) and conjunctiva (a membrane that lines the eyelids) are damaged. They also outline the tear pool and give an estimate of its volume.
Tear Break-Up Time: This test estimates the time required for your tear film to evaporate before blinking. Generally, a break-up time of less than 10 seconds indicates an abnormality in your tear film.
Slit Lamp Examination: The doctor uses a special microscope to evaluate your eyelids' health and check for mucous filaments and/or debris in the tear film.
Methods of Controlling
Two common treatments for dry eyes are to either add moisture with artificial tears or to retain moisture with punctal plugs.
Artificial Tear Substitutes
The most common treatment for dry eyes is use of non-prescription artificial tear substitutes, such as Refresh, Thera Tears, Tears Naturale and other products with no preservatives and nothing "to take the red out" (which can cause a "rebound" effect that exacerbates problems). To be effective, these drops must be used frequently—four or more times a day.
If frequent use of artificial tears doesn't provide relief, some patients undergo a simple, one-minute office procedure to place tiny silicone plugs into the drain openings ("puncta") in the corners of the eye. These painless "punctal" plugs work to block tear loss and retain natural moisture. Although punctal plugs rarely enable patients to totally stop using artificial tears, almost all find the reduction in drop use a benefit in terms of convenience and cost savings.
Newer treatment options include FDA-approved prescription eyedrops that address the inflammatory process that can cause dry eyes. These medications work to alleviate symptoms by increasing natural tear production.
Prescription Eye Drop Treatment
Restasis, Xiidra & Cequa are prescription drops that treat the inflammatory process which occurs when the surface of the eye becomes irritated by any number of environmental or physical factors, including aging, allergens, diseases, contact lenses, medications, and smoke. In a normal functioning eye, an anti-inflammatory component keeps the disruptive effect of this irritation
to a minimum. However, if this component is lacking and the irritation is not controlled, the eye does not produce adequate tears. This irritation causes the body's immune system to activate its troops of inflammatory cells, including T-lymphocytes. Thinking that the eye is under attack, these T-cells release special proteins. The resulting inflammation (of both the eye's surface and the glands that produce tears) leads to abnormal tears and symptoms of dry eye. Since the tears are abnormal, the irritated eye is not properly nourished or lubricated. This encourages the cycle of inflammation and symptoms to repeat again and again.
Restasis, Xiidra and Cequa regulate the eye’s immune reaction to dry eye stimuli by reducing the number of inflammatory cells that are activated and blocking the production of destructive inflammatory chemicals. Thus, they alleviate the symptoms (discomfort, burning, redness, etc.) of dry eye disease by treating the underlying inflammation that causes the condition in the first place. Anyone who suffers from dry eye symptoms without relief AND does not have a history of herpes eye infections may be a candidate for these drops. Beneficial effects (like decreased artificial tear use) take about two months to occur.
If you are interested in Restasis, Xiidra or Cequa, your eye care specialist can conduct tests to determine if a prescription is right for you.
Other treatment options seek to address dry eyes due to oil gland blockage. These include:
Warm Compresses and/or Eye Masks
These simple methods are often successful
for unclogging the glands when they are not producing enough oil for the tear film layer.
This is one of several MGD treatment procedures performed in a doctor’s office using a device to warm and/or massage the glands to alleviate blockage and increase oil flow.
Tips to Improve Your Comfort
It is important to remember that dry eyes are often a life-long condition that can fluctuate in severity. With proper treatment, however, dry eyes can usually be controlled. The following measures may also help to alleviate much of your discomfort, fear and frustration:
BLINK! Consciously blinking more often can help, especially when you are focused for long periods of time on a book, computer screen, smartphone, etc.
Use artificial tears frequently enough to PREVENT symptoms—DON'T wait until irritation occurs to use them.
Lessen exposure to smoke, allergens, fans, and air conditioning and heating vents.
Use a humidifier whenever possible.
Wear glasses or sunglasses to protect your eyes from the sun and wind.
Check with your eye care specialist or doctor to see if any of your medications are causing your dry eye symptoms.
For more information or a comprehensive examination . . .
Since 1985, Eye Care Specialists has provided comprehensive medical, surgical and laser care for virtually every eye condition to more than 200,000 people. If you would like our free educational booklet on the eye concern reviewed above, please complete this form or call our Communications & Education Department at 414-321-7520 ext. 217. To schedule a comprehensive eye examination or a second opinion evaluation, call any of our three convenient Milwaukee-area locations directly.