Some people suffer from a dry eye condition caused by an inability to produce enough tears to properly lubricate their eyes. This happens when a person produces tears that are abnormal or if they simply don't produce an adequate amount of tears.
Definition & Facts
In order for a person to both maintain vision and eye comfort, a flow of tears must be constant. This constant flow is necessary for the lubrication of a person's eyes. The components of healthy tears include:
- Water which provides moisture,
- Oils that provide lubrication,
- Proteins and antibodies that provide a resistance to infection,
- Mucus which helps the tears to spread evenly.
Around the eye, there are glands whose job is to secrete the components of the tears. Dry eyes develop when this tear system gets out of balance.
The eyes of a person suffering from dry eyes syndrome (DES) usually feel quite uncomfortable. Their eyes may either burn or sting. There are situations which may bring about dry eyes such as air conditioning, bike riding, being in an airplane, or hours of looking at the screen of a computer.
Symptoms & Complaints
- Sensitivity to Light (photophobia) – A person’s sensitivity to light can be a result of dry eye or an infection caused by dry eye. If the sensitivity is new to the person, it should be checked out.
- The eye feeling as if there is something in it such as sand or a foreign body.
- Redness in the eye
- Eye fatigue or blurred vision
- Fibrous mucus around or in a person's eyes
- A scratchy, burning or smarting feeling in a person's eyes
- Nighttime driving being difficult due to a limitation in seeing sufficiently.
- Wearing contact lenses being tough
- Reflex tearing -- When a person's eye becomes irritated due to dry eye, an excess of tears will run down the person's cheeks. This is because the person's eyes have sent a distress signal via the nervous system for additional lubrication. In an effort to compensate for the dryness, tears flood into the eye.
Unfortunately, these tears are lacking both the qualities of lubrication and the components of normal tears since they are primarily water. They, therefore, fail to coat the surface of the eye as they should although they do wash away foreign objects.
Dry eyes are usually caused in one of three ways. They can be caused by either a decrease in the production of tears, an increase in the evaporation of tears, or an imbalance of the composition of tears. An imbalance of the composition of tears can be the result of one of the tears’ three layers including water, mucus and oil developing problems.
A decrease in the production of tears can be caused by any of the following:
- Medical conditions such as rheumatoid arthritis, diabetes, scleroderma, lupus, disorders of the thyroid, Sjogren's syndrome and a deficiency of vitamin A.
- Radiation or inflammation damaging the tear gland
- Some medications such as decongestants, antihistamines, antidepressants, therapy for hormone replacement, birth control, acne drugs, and drugs to control [Hypertension|high blood pressure]].
- Laser eye surgery
An increase in tear evaporation can be caused by:
- Not blinking often enough such as when a person is driving, reading or working on a computer
- Environmental factors such as dry air, wind or smoke
- Problems of eyelids such as the lids out-turning and in-turning
Diagnosis & Tests
- A comprehensive eye examination: In making a diagnosis of the dry eye syndrome, a physician will begin with an all-inclusive exam of the eye. This exam will include a history of the patient's general health. The eye health of the patient will assist the doctor in diagnosing not only the existence of the dry eye condition but also the cause of it.
- Schirmer's test: A physician can measure the volume of a patient's tears with the Schirmer test. The test is performed by placing blotting-paper strips beneath the patient's lower eyelids. The total amount of the paper soaked by the patient's tears is measured by the physician after five minutes indicating the total volume of the patient’s tears.
- Eye surface condition: A physician will determine the condition of the surface of a patient's eyes through the use of eye drops containing special dyes and other tests.
- The cornea is stained with fluorescein, a yellow dye, showing whether the surface cells of the eye are worn away due to a tear film not being adequate enough to protect the eye. By seeing the patterns of staining on the cornea, the time it takes for the patient's tears to evaporate can be measured.
- Another dye used to stain the cornea as well as the conjunctiva is rose bengal, a red dye. This dye exposes the dead and dying cells. It also exposes healthy cells that the tear film is not effectively protecting.
- A green dye, Lissamon green, is used to show which of the cornea and conjunctiva surface cells are normal and which are abnormal.
- Currently, there is a new test of the osmolarity or salt content of tears. This test can help with diagnosing the dry eye syndrome (DES).
- Glands that produce mouth saliva and tears may be affected by disease. In these rare instances, a biopsy of these glands may be performed.
- By performing blood tests, a physician can determine whether autoimmune diseases are the cause of DES. If various autoantibodies are present in the blood, DES will be suspected.
Slit lamp microscope: By examining the front of a patient's eyes with this special microscope, a physician can:
- Inspect the thickness and amount of tear film
- Determine the time of the tear break-up by assessing the tear film stability
- Examine the cornea to determine whether it has been damaged or dried out
- Examine the conjunctiva in order to see whether it is too dry
Treatment & Therapy
Mild cases of DES can be treated with only a humidifier or lubricating eye drops. It is best that a person suffering from a more serious form of DES seek recommendations for treatment from a physician. Possible treatments may include:
- Tear drops: Over-the-counter tear drops are a major treatment for DES. Artificial tear drops should be used all the time by a person who suffers from dry eye chronically. This is because it is important for them to keep their eyes lubricated. People whose eyes dry out while they sleep should use a lubricant that is thicker or an ointment.
- Hydroxypropyl cellulose: Both moderate and severe DES can be helped with a tiny insert placed into the eye. This insert that looks like a grain of rice dissolves slowly and releases a substance usually used in eyedrops as a lubricant of the eye.
- Antibiotics: An infection or inflammation of a person's eyelids can prevent the oil glands from producing oil needed for a person's tears. Antibiotics taken orally or applied in the form of ointments or eyedrops may be prescribed by a physician to fight the infection.
- Ciclosporin: Ciclosporin can help a person suffering from chronic dry eye by increasing the tear production when it is used continuously. Inflammation of the cornea can be reduced by this immune suppressing medication as well.
- Drugs to stimulate tears: Tear production can be stimulated with cholinergic drugs available in the form of eyedrops, pills or gel.
- Scleral or bandage lenses: These contact lenses are especially designed to protect eye surfaces while also trapping moisture.
- Reduction of tear loss: Tear loss can be reduced through the use of punctal plugs. These tiny silicone plugs can later be removed. Another more permanent method to reduce tear loss is to use a thermal cautery solution.
- Light therapy followed by massage of eyelid: This technique is used to help a person suffering severely with dry eye.
Prevention & Prophylaxis
By wearing wraparound sunglasses, a person can protect their eyes from both dry air and wind. When reading or sitting at a computer, a person should take frequent eye breaks. It is also better to position a computer screen below the eye level and not above.
People should not only be aware of their environment but also adapt to it. For example, when riding in an airplane where the air is extremely dry, they should close their eyes for a few minutes every once in awhile. This will minimize the evaporation of their tears. Lastly, the use of artificial tears on a regular basis is strongly recommended for anyone who suffers from chronic dry eyes.