Dry Eye Syndrome is a very common eye condition that affects millions of Americans. It is estimated that dry eyes affect up to 11% of people aged 30 to 60 years of age and 15% of those 65 years of age or older. It has also been concluded that as many as 12 million Americans have moderate to severe dry eyes and that this number is likely to increase with the aging populations resulting in a significant decrease in the quality of life.
Simply, dry eyes are caused by either a deficiency in the quantity or the quality of the tears or tear film. Fortunately, today eye care patients can benefit from better diagnostic procedures for dry eyes as well as more advanced dry eye treatments from eye physicians.
Understanding the structure of tears is important in order to understand how the tears and tear film provide the eye with a number of specialized functions. Tears are composed of three layers. The innermost layer is called the mucus layer. The mucous layer acts to coat the cornea with a smooth layer of lubricating material called mucin. The mucous layer serves to provide a surface that allows the tear film to stick to the eye. The middle layer of the tear film is called the aqueous layer, and as the name implies is composed primarily of water. In fact, it is composed of about 98% water and serves to provide moisture, oxygen and nutrients to the cornea. The outermost layer of the tear film is called the lipid layer. The lipid layer is actually an oily film that acts to prevent evaporation of the tear film from the eye. A deficiency in any one or more of the tear film layers can lead to dry eyes. Eye physicians can use specialized diagnostic tests to determine which layers of the tear film are contributing to the dry eye symptoms.
Tears are produced by a number of different gland structures around the eye. The innermost layer, the mucous layer, and the outermost layer, the oily layer are produced by tiny tubular shaped glands that are in the eyelids. The middle layer, the aqueous layer, is produced by the lacrimal gland which is a structure located just under the upper eyelid. Each time you blink, the eyelids act like squeegee to smooth and spread the tear film so that it is uniform across the surface of the cornea. This smoothing of a normal tear film creates a high quality optical surface. In some cases of dry eye, the tear film is deficient enough that the eyelids cannot provide a smooth optical surface and patients then experience blurry vision that clears with repeated blinking.
Normally, excess tears flow out of the eye along the lower eyelid toward the nose and into two tiny ducts called lacrimal puncta. The lacrimal puncta open into small tube like canals that drain into the nasal passage. As a result of this connection between the drainage of tears from the eye and the nasal passage, often times when we cry we may actually experience a runny nose. Usually tears are produced on a continual basis in order to lubricate the eye. And maintain the crisp optical surface of the cornea. Reflex tears are also produced in response to pain, trauma or even an emotional event. Reflex tears tend to be overly watery and do not to alleviate a dry eye or even the symptoms of a dry eye. There are many causes of dry eye syndrome. It is extremely common for contact lens wearers to experience dry eye syndrome due to the fact that contact lens materials tend to absorb tears and protein from the tears creating dry spots on the lens surface.
The most common symptoms of dry eyes include dryness, itching, burning, irritation or grittiness, redness, blurry vision that gets clearer as you blink, light sensitivity and contrary to common sense….excessive tearing. These symptoms typically increase during vision related activities such as computer use, night driving, reading or watching television. They may also increase in response to environmental conditions such as wind, low humidity, airplane travel, or smoke (being in a smokey environment). Many of these symptoms of dry eyes may also be found in other eye conditions, this makes careful diagnosis especially important.
Sunny, dry, or windy weather, heaters, air conditioners, and arid high altitudes increase the evaporation of tears from the surface of your eyes. In fact Phoenix, Arizona was recently recognized as the 8th “Dry Eye Hotspot” in the U.S.
During the normal aging process, our bodies and our eyes produce gradually less and less oil. The reduction in oil in the tear film results in quicker evaporation leading to the formation of dry spots on our eyes.
Contact Lenses are subject to dehydration or loss of their water content. As they dehydrate, they can absorb the tear film causing dry eye symptoms. In some cases, the continued drying of the contact lens surface causes it to become deposited with protein making the lenses even more uncomfortable than the dryness alone.
Women experiencing hormonal changes (menopause), those patients suffering from thyroid disease, vitamin A deficiency, rheumatoid arthritis, lupus, psoriasis, eczema, Parkinson’s disease(or other diseases which cause decreased/insufficient blinking), acne rosacea and a number of other systemic especially autoimmune conditions may cause dry eye syndrome.
Diuretics taken for high blood pressure, antihistamines, antidepressants, acne medications, allergy meds and many others may all produce dry eye symptoms.
Certain ocular surgeries especially blepharoplasty can lead to incomplete eyelid closure and/or alterations in tear film production and thus dry eye
There are several clinical examination methods that are useful for helping to diagnose and determine the severity of dry eyes. Dr. Perry may use all or some of the following tests to help make the diagnosis:
A measurement made by observing the rate at which the tear film begins to evaporate and indicates the overall stability of the tear film.
A method of using special dyes to help highlight problems with the surface of the eye and the tear film quality. By placing these eye drops in the tear film the severity of the dryness can more easily be recognized.
A measurement made with the slit lamp biomicroscope to evaluate tear volume A Schirmer Test may be performed by placing a small piece of special paper inside your lower eyelid to measure tear production.
For those patients with mild to moderate dry eyes the first course of treatment usually is to use preservative free artificial tears. Depending on the nature of your tear film deficiency, Dr. Perry may have you use a specific type of artificial tear that has different characteristics in terms of salt content and viscosity. In addition, Dr. Perry may counsel you on environmental factors that need to be modified. Sometimes, if the oily layer of the tear film is deficient, he may suggest that you increase your consumption of oily fish or even take flax seed oil as a dietary supplement. Most likely you will be asked to drink plenty of water.
For patients with mild, moderate or severe dry eyes, who may already be using artificial tears without relief, the prescription of Restasis eye drops in addition to tears can often help alleviate your symptoms. Restasis works by suppressing a type of inflammatory cell from entering the Lacrimal Gland and thus allows the lacrimal gland to function more effectively so that you can actually make more of your own natural tears. A clinical study published in 2008 concluded that the use of Restasis eye drops may alleviate the signs and symptoms of dry eye during all stages of dry eye disease and especially in patients with mild forms of the problem. The study results for mildly affected patients suggest that the earlier the treatment with Restasis, the better the overall treatment results.
If these approaches do not work, Dr. Perry will likely suggest the insertion of tiny punctual plugs that will slow down or even stop the drainage of tears from the eye. Dr. Perry utilizes many types of punctal plugs and will specifically cater the type of plug to each individual patient. These plugs are easily and comfortably placed in the lacrimal puncta in the eyelids. Initially you may have a temporary dissolving plug put in place to see if your signs and symptoms are actually responsive to this treatment. If the results are good, it may be necessary to place a more permanent type of plug in the lacrimal puncta to affect a long-term solution. Occasionally there are some cases that may not respond to the above sequence of treatment options because of some underlying low-grade inflammatory or infectious process. In these cases it may be necessary to also prescribe an oral antibiotic such as a tetracycline or an anti-inflammatory eye drop such as a corticosteroid eye drop.
Other treatments options may include avoidance of certain environmental causes. 7Eye sunglasses can help with dry eyes because they keep out wind, pollen and dust with their Airlock seal; 99 percent of wearers in a study reported a decrease in overall dry eye symptoms. Also treating underlying medical conditions may help alleviate dry eye symptoms. Other medical products such as lacriserts, a tiny insert filled with a lubricating ingredient (hydroxypropyl cellulose) may be beneficial for some patients. The insert is placed just inside the lower eyelid, where it continuously releases lubrication for the eye throughout the day.
As you can see, the diagnosis and treatment of dry eyes is complex and requires patience and persistence on the part of the physician and the patient. With careful diagnosis and a systematic therapeutic approach, sufferers of dry eye syndrome can most often experience considerable improvement.
