Just as the last bouts of winter rolled out of Maryland and spring began painting the trees with pretty shades of green, my mother came down with a bad case of seasonal allergies. She sneezed, coughed and felt absolutely miserable for weeks, getting only mild relief from several over-the-counter medicines she tried. The worst part, in my opinion, was her temporary loss of taste given her love for spicy traditional Ghanaian dishes. I admit we all took turns teasing her about this, especially as she began to feel better. But things took on a slightly serious turn after she returned from work one day and complained of intense eye irritation, pain and blurry vision. Both eyes were clearly blood-shot from the constant hours of rubbing she had put them through.
She described a sensation of sand in her eyes but despite several examinations we could not detect a single foreign object. What was particularly concerning for me was the persistent and aggressive manner in which she rubbed at her eyes, which could have caused serious injuries to her cornea. After two days of watching this develop with no improvement, I sent her off to see our family physician, hoping he will be able to detect and remove whatever was in her eyes. She returned home several hours later with a prescription for artificial tears and a diagnosis of Dry Eye Syndrome—a relatively common disease affecting over 30 million Americans.
What is DES?
Our eyes are naturally covered with a thin layer of tears which provide constant lubrication and moisture to aid in vision and general comfort. Research demonstrates that tears are made up of three essential layers which serve the following functions:
|
Name |
Container |
Functions |
| Lipid layer (outer) | oils | provides a barrier that prevents evaporation of the aqueous layer |
| Aqueous layer (middle) | water and proteins | promotes spreading of the tear film and control infectious agents; also flushes out dust, debris or foreign objects that might get onto the eye |
| Mucous layer (inner) | mucin | coats the cornea and allows for even distribution of the tear film |
Source: Table Adapted from http://en.wikipedia.org/wiki/Tears
When one or all of these layers fail to function adequately, a person may experience dry, itchy eyes accompanied by other symptoms such as pain, light sensitivity, redness, blurry vision or a burning sensation. Others complain of a constant gritty sensation, like sand in their eyes, which can cause mild to severe discomfort. Interestingly, a few people report intermittent excessive tearing in addition to their irritating dry eye symptoms. Doctors believe that this is a reflex response to counteract the dryness sensed on the surface of the eyes through the production of large amounts of tears to restore moisture. However, since too much is produced, it generally spills down the cheeks and does not stay long enough around the eyes’ surface to be beneficial. Once the reflex system is turned off, the eyes return to their dry state again. Symptoms tend to worsen towards the end of the day after continuous use of the eyes for reading or watching television. Similar to seasonal allergies, DES seems to have an environmental-weather component with increased symptoms occurring during dry, windy, high temperatures or low humidity periods.
Causes of DES
a) Aging and menopause: DES should be of particular interest to women because several of its main causes are related to the natural progression of life that occurs in this population. Women in menopause have been found to have greater incidences of DES compared to men of similar age or women who have not yet reached this stage. Although it receives less attention compared to other symptoms of menopause such as hot flashes, mood swings and vaginal dryness, DES affects about 60% of menopausal women. It is currently believed to be a reaction to low estrogen hormone levels during this phase of life that might limit tear production.
b) Medications: DES, however, can also develop in younger women due to similar reductions in estrogen hormone levels artificially induced from taking oral contraceptive pills (OCPs). Other medications that might cause DES as a side effect include antihistamines (typically taken for allergies or asthma treatment), diuretics (used for the treatment of high blood pressure), antidepressants and beta-blockers (usually prescribed for heart problems).
c) Autoimmune diseases: This class of illness results from the body’s defense system mounting up attacks on its own cells and tissues. Such attacks can affect generally all cells in the body but the eye has a level of natural protection. However, events such as injuries to the surface of the eyes or surgeries (e.g. LASIK eye surgery) could expose the cells of the eyes to the body’s defense system leading to an autoimmune process which could affect tear production. Apart from direct eye injury, some autoimmune diseases such as Sjogren syndrome, lupus and rheumatoid arthritis have a natural predilection to cause very dry, irritated eyes.
d) Infections: Bacterial infection can occur in glands that secrete the three layers of tears resulting in either decreased production or blockage of the tear ducts that prevents secretion (see figure 1 above for anatomical positions of tear ducts). People who wear contact lenses are at increased risk of eye infections especially if they fail to clean their lenses according to recommended guidelines. Figure 2 shows several common eye inflammatory diseases that result from infection of the glands.
Treatment:
Most people who experience DES tend to have very mild, infrequent symptoms which usually do not require medical attention. Simple home remedies such as using a humidifier and filter to moisten and remove foreign debris from the air can be very helpful. Hot compresses and eyelid massages with baby shampoo can be used to treat inflammations or mild infections of the eyelids while providing a soothing feel to the eyes. Others have found artificial tears to be quite beneficial and they tend to be the first line of treatment most doctors recommend for mild to moderate dry eyes. Several brands and generic forms of artificial tears – with similar efficacy –are available over the counter. However, if you need to apply eye drops more than six times a day, consider purchasing a preservative-free solution.
People with moderate to severe DES might require prescription medications such as corticosteroids, non-steroidal anti-inflammatory drops, antibiotics or a special type of artificial tear inserts. These work by reducing the inflammatory and infectious processes, reducing incidence of corneal abrasions (from excessive rubbing/ scratching of eyes) and helping your body produce healthy tears. A few people with refractory DES resistant to other forms of treatment might benefit from a minor surgical procedure that will help improve tear flow from the ducts. As always, do discuss symptoms and treatment options with your healthcare provider who can recommend care appropriate for your specific needs.
Sources:
1) MedicineNet : Dry Eyes: http://www.medicinenet.com/dry_eyes/article.htm
2) Emedicine Health: Dry Eye Syndrome: http://www.emedicinehealth.com/dry_eye_syndrome/article_em.htm