DRY EYE SYNDROME
One of the most common reasons to see an ophthalmologist is so called “dry eye syndrome”.
The surface of the eye is normally covered with thin tear film, which acts as a lubricant between the eye and eyelids, prevents cornea from drying out, provides cornea with nutrients, and protects from pathogenic microorganisms. When the tear film breaks up, irritation of the multiple sensitive nerves in the corneal surface occurs, and symptoms of “dry eyes” develop.
Tear film consists of three layers. Internal (mucous) layer, the tear film’s foundation, is in direct contact with the surface of the eye. Middle (aqueous) layer provides hydration and nutrition of the cornea. External (lipid) layer is very thin, and it slows down evaporation of the water from the corneal surface.
Tears are made by different glands. The main tear glands, located behind upper eyelids, produce a watery (aqueous) fraction of the tear. Several smaller, accessory glands, located within the lid margins and mucous membrane of the eye, produce mucous and lipid fractions. With every blink the tear film is being spread throughout the surface of the eye. The excess of the tear is drained into the nose through the small tear ducts in the inner corner of the eye.
One of the most common causes of the dry eye syndrome is natural aging, although dry eyes can occur at young age as well. With aging our accessory tear glands produce less and less lipid fraction, for example at the age of 65 they make 40% of what they make at the age of 18. This process is more noticeable in post-menopausal women. Lack of lipid fraction affects the stability of a tear film, because it evaporates from the surface of the eye faster and causes drying of the cornea. Other factors such as hot, dry and windy climate, high altitude, air conditioning, and cigarette smoke can cause or worsen dry eye syndrome.
Many people begin to experience eye irritation when they are doing a close-up work, such as reading or working with a computer. The reason for that is that when looking in close-up people do not blink as often as they do looking at the distance. Prolonged time between blinks allows for the tear to evaporate faster, which in turn causes the cornea to dry out. Making short intervals with forceful frequent blinking improves symptoms.
Wearing of contact lenses also contribute to the development of symptoms of dryness because the lenses absorb and accumulate proteins from the tear. Certain meds, thyroid disorders, vitamin A deficiency, Parkinson and Sjogren’s diseases, rheumatoid arthritis and other connective tissue diseases can cause severe dryness. Women often develop dry eyes with menopause due to hormonal changes.
There are many symptoms of dry eye syndrome including but not limited to itching, burning, sandy/gritty feeling, irritation, redness, blurry vision improving after blinking, even excessive tearing. All these symptoms get worse while watching TV or working with a PC.
We prefer an individual approach to the treatment of dry eyes. Many patients get significant relief just using the over-the-counter artificial teardrops. They are not a medicine, but rather a lubricant, and they differ by thickness/viscosity. The thicker drops may stay on the surface of the eye for longer time. I encourage my patients to try different brands until their “eyes tell which ones they like the best”.
Sometimes in addition to the drops we offer to close tear ducts with special plugs. First we insert temporary collagen plugs which stay in the ducts for 4-5 days and then dissolve. The patient is asked to “keep a diary”. If the patient states that he or felt better while the plugs were in, we insert permanent silicone plugs. This procedure is very safe, painless and takes less than a minute.
In other cases we recommend special drops for dry eyes, RESTASIS: 1 drop twice a day, indefinitely. This is a very effective medication used in addition to the above mentioned.
Recently a new medication, XIIDRA, was approved for treatment of severe eye dryness. It is as effective as RESTASIS, and can be used as an adjunct therapy.
New modes of treatment are currently in development.