Dry eye syndrome: Causes, symptoms of chronic dry eye
Tears serve as a protective coating for the eyes, keeping the eyes moist, providing essential nutrients, and washing away dust and other particles. When the eyes don’t produce enough tears or the right quality of tears, the result is a condition that doctors commonly refer to as dry eyes. Other names for the condition include:
- keratitis sicca
- keratoconjunctivitis sicca
- dry eye syndrome
Just as the name suggests, this condition makes the eyes feel dry, scratchy, and gritty. Other symptoms may include:
- sensitivity to light
- blurry vision
- a feeling that there is a speck of dirt in the eyes
- a stringy discharge from the eyes
Dry eyes can actually cause eyes to water. This can happen when eyes are irritated. It’s similar to tear production that is triggered when something gets in your eye. They are called reflex tears.Reflex tears (the watery type that are produced in response to injury, irritation, or emotion) don’t have the lubricating qualities necessary to prevent dry eyes. Tear film is made of water, oil, and mucus, all of which are important for maintaining good eye health. The cornea, which covers the front of the eye, needs tears continuously to protect it against infection.
- external and internal eye anatomy
- eye anatomy
Most people who have dry eyes experience mild irritation with no long-term effects. But if the condition is left untreated or becomes severe, eye damage and vision loss can occur. Severe problems with dry eyes can cause:
- eye inflammation
- corneal infection
When dry eye symptoms are severe, they can interfere with quality of life. Some people may have trouble keeping their eyes open or they may not be able to work or drive. Early diagnosis and treatment can make a big difference in easing the discomfort.
Aging is one of the most common causes of dry eyes because tear production decreases as we get older.
Dry eye affects more women than men because hormonal changes (such as those that occur in pregnancy, menstruation, and menopause) can decrease tear production.
Environmental conditions can also play a role in making the eyes dry; these include:
- air conditioning
- cigarette smoke
- even hair dryers can make the eyes dry
Some people benefit from avoiding dusty, smoky areas, wearing sunglasses, and using a humidifier to moisten the surrounding air.
Not Blinking Enough
Another common culprit is not blinking enough, which happens during activities such as watching TV and computer use. Each time you blink, it coats the eye with tears. You normally blink about every 12 seconds. Studies have been conducted on people playing computer games, and it was found that some people blinked once or twice in three minutes.
Experts believe about half of all people who wear contact lenses complain of dry eyes. That’s because soft contact lenses, which float on the tear film that covers the cornea, absorb the tears in the eyes.
Laser Vision Correction and Other Procedures
Dry eye also occurs or gets worse after LASIK and other refractive surgeries, in which the corneal nerves are cut during the creation of a corneal flap. The corneal nerves stimulate tear secretion. If you’ve had dry eyes from wearing contact lenses or for any other reason and you are thinking about refractive surgery, this is something to consider.
Dry eyes also can be caused by certain medications, including:
- birth control pills
- nasal decongestants
- the prescription acne drug Accutane
Some autoimmune diseases can attack the tear glands, such as:
- lupus, an autoimmune disease that can affect many parts of the body
- rheumatoid arthritis, an inflammatory disease that causes pain, swelling, stiffness, loss of function in the joints, plus systemic effects
- Sjogren’s syndrome, an autoimmune disease in which the immune system targets moisture-producing glands, causing dryness in the mouth and eyes
Other diseases can also cause dry eyes. For example, certain types of thyroid disease can interfere with blinking. Blepharitis, an inflammation of the eyelids, can interfere with the oil glands in the eyes.
Eye doctors use a combination of routine clinical exams and other specific tests for dry eyes. For example, the Schirmer test uses a tiny strip of paper placed on the edge of the lower eyelids. This measures how much moisture is in the eye, and it’s also useful for determining the severity of the problem. Doctors may also use dye, such as fluorescein or rose bengal, which is placed on the eye to stain the surface. This is to see how much the surface of the eye has been affected by dryness. Another test, tear break-up time (TBUT), measures the time it takes for tears to break up in the eye.
The first line of treatment for dry eyes is usually over-the-counter demulcent drops, also known as artificial tears. These lubricate the eye and ease symptoms. Commonly found ingredients in these products include hydroxypropyl methylcellulose, the ingredient in Bion Tears and GenTeal, and carboxymethylcellulose, contained in Refresh Plus and Thera Tears. Always read the directions, but these products can generally be used as often as needed throughout the day.
Your healthcare provider can guide you in choosing the right one for you. Some people use drops for red eyes, but that can make the eyes even drier. Red eyes could be caused by numerous factors, from allergies to an eye infection, which is why a proper diagnosis is important. If you wear contact lenses, use rewetting drops specifically for contact lenses. Other types of drops may contain ingredients that damage the lens.
Restasis (cyclosporine ophthalmic emulsion) is the only prescription product for chronic dry eyes. Approved by the Food and Drug Administration in 2002, the drug increases tear production, which may be reduced because of inflammation on the eye surface. In a clinical trial involving 1,200 people, Restasis increased tear production in 15 percent of patients, compared with 5 percent of patients in the placebo group.Restasis is usually given twice a day, 12 hours apart. It should not be used by people with eye infections or hypersensitivity to the ingredients. It has not been tested in people with herpes viral infections of the eye. The most common side effect is a burning sensation. Other side effects may include:
- eye redness
- watery eyes
- eye pain
- foreign body sensation
- blurred vision
For people who have not found dry eye relief with drugs, punctal plugs may help. These are reserved for people with moderate or severe dry eye when other medical treatment hasn’t been adequate.In each eye, there are four puncta, little openings that drain tears into the tear ducts. Punctal plugs are inserted into the puncta to block tear drainage. Some doctors try out temporary plugs made of collagen first to make sure that permanent plugs will not cause excessive tearing. Permanent plugs are usually made of silicone. Some plugs have been approved that are made of thermally reactive material. Some of these are inserted into the punctum as a liquid and then they harden and conform to the individual’s drainage system. Others start out rigid and become soft and flexible, adapting to the individual’s punctal size after they are inserted. Artificial tears are usually still required after punctal plug insertion.Experts stress the risks of punctal plugs are fairly minimal, but there is a risk of eye irritation, excessive tearing, and, in rare cases, infection.
Omega-3 fatty acid nutritional supplements are also recommended for people with dry eyes.